Acute Cardiac Unloading and Recovery A-CURE Talks - Winter 2019

Issue Edition
Received
19 November 2019
Accepted
19 November 2019
Citation
Interventional Cardiology Review 2019;14(3 Suppl 2).
DOI
https://doi.org/10.15420/icr.2019.14.3.S2
Foreword

Welcome to this special supplement devoted to the proceedings of the 4th Annual Acute Cardiac Unloading and REcovery (A-CURE) Working Group meeting, which was held on 30 August 2019 in Paris, France. The A-CURE Working Group is comprised of leading academic experts in clinical and basic cardiac research who are dedicated to advancing the science and clinical application of acute cardiac unloading. This meeting brought together experts from multiple disciplines, including interventional cardiologists, heart failure specialists, cardiac surgeons, molecular biologists and biomedical engineers.

The 2019 symposium featured talks and posters that highlighted cutting-edge advances in the field of acute cardiac unloading that have taken place since the 2018 A-CURE symposium in Chicago, US.

Cardiac disease states, such as MI, myocarditis, cardiomyopathy and cardiogenic shock, impair the ability of the heart to pump blood, resulting in end-organ failure and, ultimately, death. Pharmacological therapies in these cases aim to maintain cardiac output, but in the process, impose further stress on the heart. Additional treatment strategies are needed. The A-CURE symposium focused on the basic science and clinical application of ventricular unloading using mechanical circulatory support technologies. Acute cardiac unloading decreases myocardial oxygen consumption and maximises the ability of the heart to rest and recover after damage. Mechanical unloading employs percutaneous ventricular assist devices, such as the Food and Drug Administration-approved Impella family of devices, to decrease the physical workload of the heart.

This supplement features a number of presentations covering a broad range of subjects related to cardiac unloading. The first session of the symposium was devoted to the advances in basic and pre-clinical science of acute unloading and myocardial salvage. Topics discussed ranged from the influence of acute unloading using Impella devices on the preservation of mitochondrial structure and function post-MI to improving intracoronary gene transduction efficiency. The impact of concomitant vasoactive treatment during active ventricular unloading in cardiogenic shock and a novel superior vena cava occlusion catheter system that reduces ventricular filling pressures while maintaining cardiac output in a model of congestive heart failure were also discussed.

In the keynote lecture, Douglas Mann shared insights on the cellular and molecular and mechanisms associated with left ventricular (LV) remodelling and reverse remodelling in a mouse model that combines clinically relevant comorbidities of moderate pressure overload and small ischaemic injury.

The second session focused on new frontiers and clinical translation of unloading. The wide spectrum of clinical studies presented included cardio-renal system interaction with the effect of haemodynamic support on acute kidney injury, the use of mechanical circulatory support for takotsubo syndrome with cardiogenic shock and clinical implications of prolonged use of Impella pumps for fulminant myocarditis with shock.

The afternoon’s presentations had a focus on the clinical translation of LV unloading. William O’Neill provided an update on the outcomes associated with the adoption of a standardised protocol for treatment in cardiogenic shock, the key features of which include the early initiation of mechanical support prior to reperfusion. Jason Williams discussed preoperative identification of high-risk cardiac surgery patients who may benefit from LV unloading with Impella. Jaime A Hernandez-Montfort presented a study of the global epidemiology and survival outcomes of patients receiving temporary circulatory support before durable ventricular assist device implantation. In the concluding talk, Navin K Kapur provided the rationale and discussed the design of the ST-elevation MI Door-To-Unload pivotal trial.

The presentations highlighted the exciting new developments and represented substantial advances in the field of acute myocardial unloading and recovery that have developed in the past year. The A-CURE Working Group meeting is unique in involving a diverse group of experts from multiple disciplines within an open, constructive and intimate public setting.

We hope that you find this supplement informative and interesting.

The State of the Field: Our Current Understanding of Ventricular Unloading

Dr Burkhoff opened the meeting by reminding the attendees about the mission of the Acute Cardiac Unloading and REcovery (A-CURE) Working Group, which is to advance the science and mechanistic understanding of acute cardiac unloading and support the translation of basic and clinical research into therapies aimed at heart muscle recovery. He noted that the A-CURE symposium is the only scientific conference dedicated entirely to acute unloading and heart recovery, and clinicians have made great strides in accomplishing the mission.

He presented a brief history of the A-CURE meetings, which began with the first faculty meeting in Paris in 2015. The annual A-CURE symposium started in Rome in 2016, followed by Barcelona in 2017, Chicago in 2018 and Paris in 2019. He highlighted the increasing number of abstracts (31 in 2016 to 63 in 2019) and accelerating science over the years, including the initiation and completion of the ST-elevation MI Door-To-Unload (STEMI-DTU) pilot trial in 2017 to the expected commencement of the STEMI-DTU pivotal trial in 2019.

Dr Burkhoff proposed a formal definition of left ventricular (LV) unloading as the reduction of total mechanical power expenditure of the ventricle, which correlates with the reduction in myocardial oxygen consumption and haemodynamic forces that lead to ventricular remodelling.1 He explained the concepts of remodelling and reverse remodelling using pressure–volume loops (PVL), emphasising that the PVL is a graphical depiction of myocardial function that holds a wide range of physiologically relevant data. He highlighted that the PVL is bound by the end-systolic pressure–volume relationship and the end-diastolic pressure–volume relationship (EDPVR), indices of contractility and diastolic function, respectively. Following an acute insult to the myocardium, there is a reduction in contractility with a reduction in stroke volume and an increase in pulmonary capillary wedge pressure (PCWP). The sustained increase in haemodynamic load and neurohormonal activation leads to the initiation of ventricular remodelling.

Prolonged ventricular remodelling manifests as the rightward shift of the PVL representing haemodynamic stress and typically results in chronic heart failure. The goal of ventricular unloading is to prevent/reverse cardiac remodelling and subsequent heart failure. When the goal of myocardial unloading using mechanical circulatory support is achieved, it results in decreased PCWP, decreased myocardial oxygen consumption, improved subendocardial coronary blood flow, salvage of myocardium and limits/reverses remodelling (Figure 1).

He noted that the benefits of LV unloading are well-documented in basic and clinical literature. The seminal work by Pfeffer et al. in 1985 demonstrated the benefits of LV unloading using captopril, an angiotensin-converting enzyme (ACE) inhibitor, in a rat model of MI.2 They showed that during a large untreated MI, the EDPVR is markedly shifted rightwards compared to normal conditions, reflecting acute pressure and volume overload in the LV. However, the degree of EDPVR rightward shift is blunted following treatment with captopril. This pre-clinical finding was tested in a clinical trial that showed a significant reduction in end-diastolic pressure and PCWP with the resultant decrease in ventricular dilatation with captopril.3 These studies were followed by additional trials, such as the Survival and Ventricular Enlargement (SAVE) trial, that were critical in establishing ACE inhibitors as therapies for the treatment of MI.

Definition of Myocardial Unloading and Benefits During MI

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However, there are inherent limitations to myocardial unloading using pharmacological therapies. Importantly, more unloading of the LV through pharmacological means leads to more compromise in aortic pressure and cardiac output. Hence, pharmacological therapies are inherently limited in their ability to unload the heart. On the other hand, the use of a percutaneous ventricular assist device, such as Impella, can simultaneously unload the ventricle and reduce the workload of the heart while increasing end-organ perfusion as perfusion pressure is maintained. In 2003, Meyns et al. demonstrated that LV unloading using Impella reduced myocardial oxygen consumption resulting in reduced infarct size in a sheep model of ischaemia–reperfusion.4 The study by Kapur et al. of a pig model of ischaemia–reperfusion injury further demonstrated that mechanical pre-conditioning with acute circulatory support before reperfusion limits infarct size in acute MI.5 These results led to the STEMI-DTU pilot trial in humans assessing the safety and feasibility of primary unloading with Impella followed by delayed reperfusion in patients with STEMI. The study confirmed the safety and feasibility of primary unloading, followed by delayed reperfusion, and showed that the infarct size was relatively independent of the area at risk. The results of the pilot study are the basis for moving forward with the STEMI-DTU pivotal trial, expected to start in December 2019.

Additional studies have shown that LV unloading in chronic heart failure can also induce reverse remodelling. Levin et al. showed that the EDPVR of hearts from patients with end-stage idiopathic cardiomyopathy were shifted rightwards towards markedly larger volumes compared to normal hearts.6 However, chronic haemodynamic unloading with LV assist devices resulted in the leftward shift of the EDPVR towards lower volumes, similar to those of normal hearts. Additional studies have demonstrated that the unloading-induced reverse remodelling in chronic heart failure is both dose- and time-dependent.7,8

Dr Burkhoff concluded that this year’s A-CURE symposium will showcase advances in the science of unloading and myocardial salvage from basic science and clinical research.

References

  1. Uriel N, Sayer G, Annamalai S, et al. Mechanical unloading in heart failure. J Am Coll Cardiol 2018;72:569–80.
    Crossref | PubMed
  2. Pfeffer JM, Pfeffer MA, Braunwald E. Influence of chronic captopril therapy on the infarcted left ventricle of the rat. Circ Res 1985;57:84–95.
    Crossref | PubMed
  3. Pfeffer MA, Lamas GA, Vaughan DE, et al. Effect of captopril on progressive ventricular dilatation after anterior myocardial infarction. N Engl J Med 1988;319:80–6.
    Crossref | PubMed
  4. Meyns B, Stolinski J, Leunens V, et al. Left ventricular support by catheter-mounted axial flow pump reduces infarct size. J Am Coll Cardiol 2003;41:1087–95.
    Crossref | PubMed
  5. Kapur NK, Qiao X, Paruchuri V, et al. Mechanical pre-conditioning with acute circulatory support before reperfusion limits infarct size in acute myocardial infarction. JACC Heart Fail 2015;3:873–82.
    Crossref | PubMed
  6. Levin HR, Oz MC, Chen JM, et al. Reversal of chronic ventricular dilation in patients with end-stage cardiomyopathy by prolonged mechanical unloading. Circulation 1995;91:2717–20.
    Crossref | PubMed
  7. Madigan JD, Barbone A, Choudhri AF, et al. Time course of reverse remodeling of the left ventricle during support with a left ventricular assist device. J Thorac Cardiovasc Surg 2001;121:902–8.
    Crossref | PubMed
  8. Jacobs S, Geens J, Rega F, et al. Continuous-flow left ventricular assist devices induce left ventricular reverse remodeling. J Heart Lung Transplant 2013;32: 466–8.
    Crossref | PubMed
A Novel Imaging Probe for the Detection of Autophagy in Pre-clinical Pig Models of Myocardial Ischaemia–Reperfusion Injury

Dr Chen presented his findings on the role of autophagy in myocardial ischaemia–reperfusion (IR) injury based on a novel molecular imaging technique in a pre-clinical pig model. He began by highlighting that cardiomyocyte death is a hallmark of acute MI (AMI). He provided background by describing the three types of cellular death pathways (apoptosis, necrosis and autophagy), and the complex cross-talk between these cell death mechanisms.1 Apoptosis is programmed, while necrosis is an irreversible cell death. Autophagy is an evolutionarily conserved catabolic cellular process, during which cells digest organelles in their cytoplasm and recycle the constituents. Autophagy is thought to play an important role in many cardiovascular diseases. The pathophysiological impact of autophagy has been shown to promote cardiomyocyte death or recovery. A major barrier in the study of autophagy is the inability to accurately detect and quantify autophagosomes within the area at risk during AMI.

Dr Chen proposed that in vivo imaging may aid in quantification and provide mechanistic insights of these different cell death pathways during AMI. He noted that the annexin V-magnetic nanoparticle AnxCLIO-Cy5.5 was previously demonstrated to detect apoptosis in vivo by MRI with good spatial resolution in a mouse heart following AMI.2–4 More recently, a gadolinium–thiazole-based nanoparticle, which binds to the exposed DNA of ruptured cardiomyocytes, was demonstrated to detect necrosis in vivo by MRI in mouse heart following AMI.5–7

He stated that fluorescence imaging allows multiplexing, and thus plays an important part in understanding the fate of individual cells through the cell death pathways. Likewise, multiplexed imaging using nanoparticle probes is feasible and reveals additional insights, suggesting that early cardiomyocyte apoptosis may be reversible.

Dr Chen described in detail the molecular events during autophagy and emphasised that an expanded lysosomal compartment upon formation of the autolysosome is a hallmark of autophagy.8 He described two autophagy imaging constructs that reflect lysosomal enzyme (cathepsin) activity: cathepsin-activatable fluorochrome (CAF) and autophagy-detecting nanoparticle (ADN).9,10 ADN was rationally designed for enhanced sensitivity of autophagy detection and is based on a Food and Drug Administration (FDA)-approved drug, Feraheme (ferumoxytol), which is surface decorated with CAF peptides. The advantages of the ADN probe include dual near-infrared fluorescent and MRI readouts.

Dr Chen presented the results of ADN imaging of cardiomyocyte autophagy in a mouse model involving 24-hour starvation. Compared to the fed control mice, autophagy was induced in the starved mice and was detected by increased uptake of the ADN probe, both by MRI and fluorescent imaging. Systemic profiling of the ADN fluorescence showed increased autophagy (ADN levels) in the heart, spleen and small intestine compared to other organs, such as the lung, kidney or liver.

Next, Dr Chen presented his current hypothesis that the ADN, based on ferumoxytol, used to target lysosomal compartments during autophagy in vivo, could provide a robust fluorescent readout of autophagy levels in animal models of AMI. This hypothesis was tested using both mouse and pig models of IR injury.

Mice were subjected to 35 minutes of ischaemia by ligation of the left coronary artery, followed by 4 hours of reperfusion. At the onset of reperfusion, both ADN and CAF (internal control) probes were co-injected intravenously via the tail vein for ex vivo imaging. The results showed that ADN detects autophagy in IR mice (n=5) and is far more sensitive than CAF (n=5). Importantly, ADN activation was specific and localised in the ischaemic myocardium.

Treatment with rapamycin, a robust activator of autophagy through inhibition of the protein kinase mammalian target of rapamycin, led to a reduction in apoptosis by 23% and infarct size by 45%, thus providing molecular insights on the role of autophagy.10

In the pig model of AMI, adult swine were subjected to 2 hours of ischaemia by left anterior descending artery occlusion, followed by 30 minutes of mechanical support with Impella or extracorporeal membrane oxygenation (ECMO) and finally 2 hours of reperfusion. The ADN probe was injected intracoronary during reperfusion for ex vivo imaging. As expected from the results of the mouse model, a significant increase in ADN signal was seen in the area at risk compared to the uninjured (septal) myocardium. Of note, reperfusion significantly increased autophagosome formation (indicated by light chain 3B-II levels), which was attenuated by Impella (n=4), but not by ECMO (n=4).

In conclusion, this study demonstrates the feasibility of quantitative autophagy imaging in the heart following AMI and shows that unloading with Impella and ECMO differentially impacts autophagy. Future studies will focus on characterising additional molecular readouts of autophagy in unloaded swine hearts after AMI to further advance the translation of the novel autophagy imaging technology.

References

  1. Hotchkiss RS, Strasser A, McDunn JE, et al. Cell death. N Engl J Med 2009;361:1570–83.
    Crossref | PubMed
  2. Sosnovik DE, Schellenberger EA, Nahrendorf M, et al. Magnetic resonance imaging of cardiomyocyte apoptosis with a novel magneto‐optical nanoparticle. Magn Reson Med 2005;54:718–24.
    Crossref | PubMed
  3. Sosnovik DE, Nahrendorf M, Panizzi P, et al. Molecular MRI detects low levels of cardiomyocyte apoptosis in a transgenic model of chronic heart failure. Circ Cardiovasc Imaging 2009;2:468–75.
    Crossref | PubMed
  4. Chen HH, Yuan H, Cho H, et al. Cytoprotective nanoparticles by conjugation of a polyhis tagged annexin V to a nanoparticle drug. Nanoscale 2015;7:2255–9.
    Crossref | PubMed
  5. Huang S, Chen HH, Yuan H, et al. Molecular MRI of acute necrosis with a novel DNA-binding gadolinium chelate: kinetics of cell death and clearance in infarcted myocardium. Circ Cardiovasc Imaging 2011;4:729–37.
    Crossref | PubMed
  6. Cho H, Guo Y, Sosnovik DE, Josephson L. Imaging DNA with fluorochrome bearing metals. Inorg Chem 2013;52:12216–22.
    Crossref | PubMed
  7. Chen HH, Yuan H, Cho H, et al. Theranostic nucleic acid binding nanoprobe exerts anti-inflammatory and cytoprotective effects in ischemic injury. Theranostics 2017;7:814–25.
    Crossref | PubMed
  8. Stolz A, Ernst A, Dikic I. Cargo recognition and trafficking in selective autophagy. Nat Cell Biol 2014;16:495–501.
    Crossref | PubMed
  9. Mahmood U, Tung CH, Bogdanov A Jr, Weissleder R. Near-infrared optical imaging of protease activity for tumor detection. Radiology 1999;213:866–70.
    Crossref | PubMed
  10. Chen HH, Mekkaoui C, Cho H, et al. Fluorescence tomography of rapamycin-induced autophagy and cardioprotection in vivo. Circ Cardiovasc Imaging 2013;6:441–7.
    Crossref | PubMed
Left Ventricular Unloading and Delaying Coronary Reperfusion Preserves Energy Substrate Utilisation and Protects Mitochondrial Integrity in a Pre-clinical Model of Acute MI

Dr Swain began by highlighting that haemodynamic load is a major determinant of acute and chronic ventricular remodelling.1 This led her to question if acute ventricular unloading can be used as a therapeutic strategy to improve myocardial recovery. She recalled the observation by Mann et al. that the myocardial damage due to acute MI (AMI) is reversible following the reduction of left ventricular (LV) pressure and volume.2 Studies have demonstrated that LV unloading reduces myocardial oxygen consumption, which is driven by myocyte cycling, excitation-contraction coupling and basal metabolism. Previous studies have shown that transvalvular pumps, such as Impella, rapidly unload the LV without the need for surgery.3,4 In addition, emerging research comparing reperfusion alone to LV unloading prior to reperfusion has demonstrated that the unloading strategy reduces infarct size, despite delaying reperfusion by 60 minutes in a pig model.4,5 The recent ST-elevation MI Door-To-Unload pilot trial demonstrated the safety and feasibility of LV unloading and delayed reperfusion (U-DR) in patients with ST-elevation MI.6 The results of the subgroup analysis showed that U-DR reduced infarct size compared to unloading and immediate reperfusion.

Given the results of a previous study showing that LV unloading preserves mitochondrial structure and levels of genes associated with mitochondrial function,5 Dr Swain hypothesised that LV unloading before reperfusion preserves mitochondrial structural and functional integrity in AMI. To test the effect of LV unloading on mitochondrial function, adult male pigs subjected to left anterior descending artery (LAD) occlusion for 90 minutes were divided into three groups. In the continued occlusion group, LAD was occluded for an additional 30 minutes, followed by 180 minutes of reperfusion. In the Impella pre-reperfusion group, Impella CP at maximal support was activated with LAD occlusion for an additional 30 minutes, followed by 180 minutes of reperfusion. In the veno-arterial extracorporeal membrane oxygenation (VA-ECMO) pre-reperfusion group, VA-ECMO at 7,500 rpm was activated with LAD occlusion for an additional 30 minutes, followed by 180 minutes of reperfusion.

The results showed that unloading with Impella CP before reperfusion compared to VA-ECMO reduced infarct size, despite equal exposure to LAD occlusion. Also, oxygen consumption rates measured using the Agilent Seahorse Platform on tissue harvested from within the infarct zone showed that primary unloading using Impella CP preserves the function of mitochondrial complex 1 in AMI compared to reperfusion alone. On the other hand, primary unloading with VA-ECMO led to a significant decrease in mitochondrial respiration via complexes I, II and III compared to reperfusion alone. Furthermore, unloading with Impella before reperfusion reduced the increase in complex I deactivation observed in the infarct zone due to ischaemia–reperfusion (IR) injury compared to VA-ECMO or reperfusion alone.

Along the same lines, oxidative stress biomarkers (catalase activity and glutathione levels) in Impella-treated animals were similar to sham-treated animals, indicating the prevention of oxidative stress and subsequent reactive oxygen species production following unloading with Impella in AMI. Dr Swain tested whether unloading with Impella impacted myocardial metabolism. Her findings suggested that unloading with Impella preserved glycolytic and Krebs cycle activity compared to IR injury alone or unloading with VA-ECMO.

Dr Swain also tested if LV unloading during ischaemia without reperfusion reduced infarct size and preserved mitochondrial function. To address this question, adult male swine were subjected to either 90 minutes of LAD occlusion, followed by an additional 120 minutes of occlusion (ischaemia), or 90 minutes of LAD occlusion, followed by 120 minutes of additional ischaemia with concurrent LV unloading with Impella (ischaemia and unloading). The results demonstrate that ischaemia and unloading significantly reduced the infarct size and preserved mitochondrial function compared to ischaemia alone. The results indicate that LV unloading may be able to limit ischaemia-dependent damage.

In summary, these findings suggest that LV unloading prior to reperfusion with Impella reperfusion versus VA-ECMO reduces infarct size and preserves mitochondrial function after IR injury. Also, the results indicate for the first time that unloading with Impella during ischaemia without reperfusion reduces infarct size and preserves mitochondrial function after prolonged ischaemic injury.

References

  1. Whelan RS, Mani K, Kitsis RN. Nipping at cardiac remodeling. J Clin Invest 2007;117:2751–3.
    Crossref | PubMed
  2. Mann DL, Barger PM, Burkhoff D. Myocardial recovery and the failing heart: myth, magic, or molecular target? J Am Coll Cardiol 2012;60:2465–72.
    Crossref | PubMed
  3. Kapur NK, Paruchuri V, Urbano-Morales JA, et al. Mechanically unloading the left ventricle before coronary reperfusion reduces left ventricular wall stress and myocardial infarct size. Circulation 2013;128:328–36.
    Crossref | PubMed
  4. Kapur NK, Qiao X, Paruchuri V, et al. Mechanical preconditioning with acute circulatory support before reperfusion limits infarct size in acute myocardial infarction. JACC Heart Fail 2015;3:873-82.
    Crossref | PubMed
  5. Esposito ML, Zhang Y, Qiao X, et al. Left ventricular unloading before reperfusion promotes functional recovery after acute myocardial infarction. J Am Coll Cardiol 2018;72:501–14.
    Crossref | PubMed
  6. Kapur NK, Alkhouli MA, DeMartini TJ, et al. Unloading the left ventricle before reperfusion in patients with anterior ST-segment-elevation myocardial infarction. Circulation 2019;139:337–46.
    Crossref | PubMed
Concomitant Vasoactive Treatment and Mechanical Unloading in an Experimental Porcine Model of Profound Cardiogenic Shock: Impact on Left Ventricular Function and End-organ Perfusion

Dr Udesen opened her talk by stating the clinical relevance of testing vasoactive drugs concomitant with mechanical unloading in cardiogenic shock (CS). She highlighted that, according to the 2017 European Society of Cardiology guideline for the management of acute MI (AMI) in patients with ST-segment elevation MI, both inotropes and short-term mechanical support devices might be considered for haemodynamic stabilisation (Class IIb); however, the level of evidence is weak.1,2 A recent publication assessing the temporal trends of CS in AMI in Denmark reported the increasing use of mechanical circulatory support with Impella devices, and the use of ≥1 vasoactive drug in about 90% of cases.3 She described the clinical conundrum involving patients with CS and low perfusion pressure and the decision to use an inotrope or vasoconstrictor to increase end-organ perfusion. This increase in perfusion pressure comes at the expense of increased cardiac afterload, and hence an increase in left ventricular (LV) workload.

To aid in the choice of the vasoactive drug, Dr Udesen compared the effect of norepinephrine (NA), epinephrine (AD), dopamine (DA) and phenylephrine (PE) on pressure–volume area (PVA), LV workload (product of PVA and heart rate) and metabolism in a pig model of ischaemic cardiogenic shock supported by Impella CP (n=10).

CS was induced using stepwise injections of polyvinyl microspheres and was defined as mixed venous oxygen saturation (SvO2) to <30% or ≤50% of baseline value and/or sustained cardiac index <1.5l/min/m2 for ≥10 minutes. The multiple steps of the experiment included instrumentation, development of CS, initiation of support with Impella CP for 30 minutes, administration of minimal NA (if the mean arterial pressure declined to <50 mmHg), blinded crossover to drug infusion for 30 minutes each (AD 0.1 µg/kg/min, NA 0.1 µg/kg/min and DA 10 µg/kg/min), PE infusion for 20 minutes and euthanasia. A linear mixed model was constructed using individual animals as subjects for random factors and sequential experimental stages as fixed repeated measurements. The reference time was set to 30 minutes after initiation of Impella CP support.

Concomitant administration of NA with Impella CP resulted in a leftward shift of the pressure–volume loop (PVL) with an increase in stroke work. Similar results were observed with DA (slightly more pronounced) and AD. However, concomitant administration of PE with Impella CP resulted in a rightward shift of the PVL, with an increase in end-diastolic pressure (LVEDP). Compared to treatment with Impella (reference), AD increased heart rate by 1.2-fold, DA and PE by about 1.4-fold, while no difference was observed with NA. LVEDP increased significantly only with PE and not with reference and other vasoactive drugs. In contrast, LV stroke work increased to different degrees with AD, DA and NA, with no difference with PE. Also, the PVA increased with all four drugs, compared to treatment with Impella. These data indicate that the total LV workload increased with all four drugs compared to treatment with Impella alone, and reached statistical significance in all drug treatment groups, except NA.

The arterial lactate concentration and renal and cerebral oxygen saturation were measured to assess the status of end-organ perfusion. Compared to reference, SvO2 increased with AD, DA and NA, but decreased significantly with PE. Treatment with PE significantly increased arterial lactate levels and decreased renal venous oxygen compared to treatment with Impella. Treatment with DA significantly increased cerebral SvO2 compared to treatment with Impella.

Taken together, the results suggest that if the perfusion pressure remains low after initiating support with Impella CP in CS, NA should be the first vasoactive drug of choice because it exhibits mild inotropic and potent vasopressor effects. The use of PE, which exhibits only vasopressor effects, should be avoided.

References

  1. Ibanez B, James S, Agewall S,et al. 2017 ESC guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation: The Task Force for the management of acute myocardial infarction in patients presenting with ST-segment elevation of the European Society of Cardiology (ESC). Eur Heart J 2018;39:119–77.
    Crossref | PubMed
  2. Thiele H, Ohman EM, de Waha-Thiele S, et al. Management of cardiogenic shock complicating myocardial infarction: an update 2019. Eur Heart J 2019;40:2671–83.
    Crossref | PubMed
  3. Helgestad OKL, Josiassen J, Hassager C, et al. Temporal trends in incidence and patient characteristics in cardiogenic shock following acute myocardial infarction from 2010 to 2017: a Danish cohort study. Eur J Heart Fail 2019.
    Crossref | PubMed
Improving Cardiac Gene Therapy Efficacy Using Impella

Dr Ishikawa began by recalling that acute MI (AMI) was a deadly disease about 50 years ago, but advances in acute care, including early coronary revascularisation, have led to a significant decline in mortality.1,2 However, it has led to a parallel increase in the prevalence of heart failure (HF) and the subsequent increase in costs of care.3,4 In essence, the therapeutic advances in the management of AMI over the past few decades have led to a detour to the final destination of death that now goes through HF. He highlighted the research initiatives and publications by the Acute Cardiac Unloading and REcovery faculty in the past several years attempting to stem the development of HF following an AMI via mechanical unloading.5–10 This raises the question of what therapies can benefit patients who have already developed HF and prevent them from premature death. Dr Ishikawa’s team tested the idea of utilising mechanical left ventricular (LV) unloading to increase the efficacy of delivering cardiac gene therapy vectors in patients with established HF.

He highlighted the poor results of the phase IIb trial, Calcium Up-Regulation by Percutaneous Administration of Gene Therapy In Cardiac Disease (CUPID 2), which investigated the intracoronary administration of adeno-associated virus type 1 (AAV1)/SERCA2a gene in patients with Class III/IV HF.11 Possible reasons for the failure of the trial include insufficient myocardial uptake of the transduced gene, as the AAV concentration was very low. He then described the antegrade intracoronary injection of the gene therapy vector, which is advantageous given the relatively low invasiveness and homogeneous distribution. However, data on this approach demonstrate that the cardiac uptake of the vector is low and so requires a high vector dose to compensate.

Studies suggest that efficient cardiac gene transfer efficiency with AAV vectors can be achieved with high perfusion pressure, coronary flow, vector dose and longer exposure times. Dr Ishikawa presented his hypothesis of improving gene delivery by using the Impella device to enhance viral uptake. He proposed that Impella support could affect uptake in two ways. First, LV unloading with Impella will result in a decrease in LV wall stress and an increase in coronary flow and pressure. Second, Impella could be used to haemodynamically support the patient while the vector is delivered into the coronary system during temporary coronary balloon occlusion. This would allow for a longer dwell time by slowing the coronary perfusion rate and minimising the risk of haemodynamic collapse.

Dr Ishikawa tested the haemodynamic support approach with Impella in a pig model of subacute ischaemic HF. AMI is induced and the heart is allowed to remodel for 1 week. After 1 week, the AAV-6-Luc (5.0 × 1013) is delivered intracoronary, with or without Impella support (n=3 each), and the hearts were analysed for luciferase activity after 4 weeks. No clear benefit of unloading with Impella alone was observed when using antegrade intracoronary delivery of the AAV vector with a luciferase gene construct.

Next, he tested gene delivery via coronary occlusion, with or without Impella. All pigs tolerated temporary balloon occlusion in the infarcted left anterior descending artery with no change in the systolic aortic pressure, both with and without Impella. However, the systolic aortic pressure dropped to <60 mmHg in all pigs treated with balloon occlusion in the non-infarcted left circumflex artery without Impella, while this was maintained in pigs receiving Impella support. The delivery of the AAV vector via coronary artery (CA) balloon occlusion with Impella resulted in approximately a 20-fold increase in the expression of the transduced gene. Moreover, delivery of the AAV vector using a combination of CA and coronary sinus occlusion with Impella support resulted in an up to 800-fold increase in the transduced gene expression, comparable to intramyocardial exposure via surgical approach. All animals supported with Impella during simultaneous CA and sinus occlusion were haemodynamically stable throughout the procedure.

In conclusion, these results demonstrate that haemodynamic support with Impella allows for safe and efficacious AAV gene delivery to the heart. Future studies include testing the above model with a therapeutic gene and delineating the mechanisms leading to high gene transduction.

References

  1. Ezekowitz JA, Kaul P, Bakal JA, et al. Declining in-hospital mortality and increasing heart failure incidence in elderly patients with first myocardial infarction. J Am Coll Cardiol 2009;53:13–20.
    Crossref | PubMed
  2. Rahimi K, Duncan M, Pitcher A, et al. Mortality from heart failure, acute myocardial infarction and other ischaemic heart disease in England and Oxford: a trend study of multiple-cause-coded death certification. J Epidemiol Community Health 2015;69:1000–5.
    Crossref | PubMed
  3. Mozaffarian D, Benjamin EJ, Go AS, et al. Heart disease and stroke statistics – 2015 update: a report from the American Heart Association. Circulation 2015;131:e29–322.
    Crossref | PubMed
  4. Heidenreich PA, Trogdon JG, Khavjou OA, et al. Forecasting the future of cardiovascular disease in the United States: a policy statement from the American Heart Association. Circulation 2011;123:933–44.
    Crossref | PubMed
  5. Meyns B, Stolinski J, Leunens V, et al. Left ventricular support by catheter-mounted axial flow pump reduces infarct size. J Am Coll Cardiol 2003; 41:1087–95.
    Crossref | PubMed
  6. Saku K, Kakino T, Arimura T, et al. Left ventricular mechanical unloading by total support of Impella in myocardial infarction reduces infarct size, preserves left ventricular function, and prevents subsequent heart failure in dogs. Circ Heart Fail 2018;11:e004397.
    Crossref | PubMed
  7. Saku K, Kakino T, Arimura T, et al. Total mechanical unloading minimizes metabolic demand of left ventricle and dramatically reduces infarct size in myocardial infarction. PLoS One 2016;11:e0152911.
    Crossref | PubMed
  8. Esposito ML, Zhang Y, Qiao X, et al. Left ventricular unloading before reperfusion promotes functional recovery after acute myocardial infarction. J Am Coll Cardiol 2018;72:501–14.
    Crossref | PubMed
  9. Sunagawa G, Saku K, Arimura T, et al. Mechano-chronotropic unloading during the acute phase of myocardial infarction markedly reduces infarct size via the suppression of myocardial oxygen consumption. J Cardiovasc Transl Res 2019;12:124–34.
    Crossref | PubMed
  10. Kapur NK, Qiao X, Paruchuri V, et al. Mechanical pre-conditioning with acute circulatory support before reperfusion limits infarct size in acute myocardial infarction. JACC Heart Fail 2015;3:873–82.
    Crossref | PubMed
  11. Greenberg B, Butler J, Felker GM, et al. Calcium upregulation by percutaneous administration of gene therapy in patients with cardiac disease (CUPID 2): a randomised, multinational, double-blind, placebo-controlled, phase 2b trial. Lancet 2016;387:1178–86.
    Crossref | PubMed
Reversal of MI-induced Changes in Gene Expression by Ventricular Unloading in Rats

Dr Ehmke outlined that many studies have shown that mechanical unloading of the left ventricle (LV) may support the recovery of myocardium after an ischaemic insult, yet the molecular mechanisms underlying this reverse remodelling are largely unclear.1 His team hypothesised that ventricular unloading leads to the normalisation of genes dysregulated after MI, and this normalised gene expression plays a role in reverse cardiac remodelling. The hypothesis was tested via an unbiased transcriptomic approach aimed at identifying relevant genetic pathways in 12-week-old male Lewis rats. MI was induced by coronary ligation of the left anterior descending artery or sham surgery was performed, followed by an assessment of LV function at 6 weeks. Cardiac gene expression was assessed at 8 weeks using the Affymetrix GeneChip. A subset of the MI-induced and sham rats received mechanical unloading using a syngeneic heterotopic transplanted heart at 6 weeks, followed by assessment of cardiac gene expression at 8 weeks.2

At 6 weeks post-MI, the LV ejection fraction in the MI-induced rats had decreased from 75% to about 25%, along with a significant increase in the LV internal diameter compared to the baseline. The gene expression profiling showed that, in infarcted heart MI, about 1,000 genes were dysregulated, with 874 genes being downregulated and 182 genes being upregulated compared to sham controls. Following unloading, 101 of the 874 downregulated genes and 32 of the 182 upregulated genes were normalised. Further analysis showed that most of the genes normalised by unloading were involved in the Hippo signalling pathway, known to play a key role in cardiac development, cardiomyocyte homeostasis and regeneration.3

In conclusion, MI in rats led to dysregulation of about 1,000 cardiac genes, and mechanical unloading normalised the expression of about 10% of the dysregulated genes. Preliminary analyses suggest that modulation of the Hippo pathway may contribute to the beneficial effects of LV unloading in ischaemic hearts.

References

  1. Wever-Pinzon J, Selzman CH, Stoddard G, et al. Impact of ischemic heart failure etiology on cardiac recovery during mechanical unloading. J Am Coll Cardiol 2016;68:1741–52.
    Crossref | PubMed
  2. Westhofen S, Jelinek M, Dreher L, et al. The heterotopic heart transplantation in mice as a small animal model to study mechanical unloading – establishment of the procedure, perioperative management and postoperative scoring. PLoS One 2019;14:e0214513.
    Crossref | PubMed
  3. Zhou Q, Li L, Zhao B, Guan KL. The Hippo pathway in heart development, regeneration, and diseases. Circ Res 2015;116:1431–47.
    Crossref | PubMed
A Novel Superior Vena Cava Occlusion System for the Treatment of Acute Congestive Heart Failure: Pre-clinical and Clinical Data

Dr Burkhoff began by stating that the Acute Cardiac Unloading and REcovery symposium is focused on ventricular unloading using mechanical circulatory support devices to improve or maintain myocardial function. Laboratories around the world are investigating other novel methods for ventricular unloading and improving the haemodynamic status of other end-organs. He stated that congestion plays an important role in acute decompensated heart failure (ADHF) and is an important target of therapy.1 It is characterised by elevated filling pressures, clinical signs of dyspnoea, peripheral oedema, ascites and end-organ dysfunction resulting in poor prognosis. Studies suggest that venous congestion reduces glomerular filtration and limits urine output, thereby attenuating the effects of diuretics and promoting HF.2,3

Existing approaches to reduce congestion are limited. Hence, there exists a need for rapid and effective cardiac decongestion in patients with ADHF. Dr Burkhoff highlighted a recent significant effort aimed at decreasing congestion: decrease central venous pressure and pulmonary capillary wedge pressure (DRIPPS). One of the components of DRIPPS includes a class of devices/drugs nicknamed ‘pullers’, whose mechanism of action is to decrease the central venous pressure or pulmonary capillary wedge pressure by ‘pulling’ volume out of the venous system. This effect of pullers should decongest the patient and promote increased end-organ perfusion by increasing the arterial-to-venous pressure gradient. Pullers also include devices that can transiently occlude the superior vena cava (SVC), leading to reduced cardiac filling pressures without reducing cardiac output (CO) or systemic blood pressure. Because SVC accounts for only about 30% of venous return, it was postulated that the SVC could be totally occluded, potentially with less impact on CO or systemic blood pressure, with a subsequent reduction in end-organ venous pressure.

The recent pre-clinical publication from Kapur et al. showed that while the inferior vena cava occlusion reduced CO, left ventricular end-systolic pressure (LVESP) and left ventricular end-diastolic pressure (LVEDP), SVC occlusion on the other hand led to a reduction in only LVEDP with no effect on CO or LVESP.4

The encouraging results of the pre-clinical studies led to the clinical proof-of-concept study to provide initial evidence of safety and feasibility of transient SVC occlusion in patients with ADHF and reduced ejection fraction (<40%), who were referred for cardiac catheterisation.4 SVC occlusion was performed using a commercially available occlusion balloon in eight patients with systolic heart failure. Five minutes of SVC occlusion reduced biventricular filling pressures without decreasing systemic blood pressure or total cardiac output in five of the eight patients. In three of the eight patients, a second 10-minute occlusion period had similar haemodynamic effects. SVC occlusion was well-tolerated without the development of new symptoms, new neurological deficits or any adverse events, including stroke, heart attack or reported SVC injury or thrombosis at 7 days of follow-up. The favourable results of this proof-of-concept study have led to the prospective, multicentre early feasibility and safety study of the preCARDIA system in the SVC Occlusion in Subjects With Acute Decompensated Heart Failure (VENUS-HF) study.

In conclusion, venous congestion is an important prognostic indicator of ADHF and CS and contributes to impaired end-organ function. In an early clinical study testing transient SVC occlusion, this approach appears to be a safe therapeutic approach to rapidly reduce cardiac filling pressures in HF, while preserving blood pressure and CO and increasing urine output.

References

  1. Cooper LB, Mentz RJ, Stevens SR, et al. Hemodynamic predictors of heart failure morbidity and mortality: fluid or flow? J Card Fail2016;22:182–9.
    Crossref | PubMed
  2. Damman K, Tang WH, Testani JM, McMurray JJ. Terminology and definition of changes renal function in heart failure. Eur Heart J 2014;35:3413–6.
    Crossref | PubMed
  3. Mullens W, Abrahams Z, Francis GS, et al. Importance of venous congestion for worsening of renal function in advanced decompensated heart failure. J Am Coll Cardiol 2009;53:589–96.
    Crossref | PubMed
  4. Kapur NK, Karas RH, Newman S, et al. First-in-human experience with occlusion of the superior vena cava to reduce cardiac filling pressures in congestive heart failure. Catheter Cardiovasc Interv 2019;93:1205–10.
    Crossref | PubMed
Plenary Lecture: The Role of Haemodynamic Load in Left Ventricular Remodelling and Reverse Remodelling

Dr Mann’s talk focused on his investigations on the role of haemodynamic load in left ventricular (LV) remodelling and reverse remodelling. The biology of cardiac remodelling involves three main components in succession: myocyte and myocardial alterations resulting in alterations to LV geometry. His early work in 1989 provided the first evidence that an increase in load on adult mammalian cardiomyocyte can activate hypertrophy.1 Numerous studies have since shown that cardiomyocyte stretch alone is sufficient to activate multiple growth pathways, although the exact stretch receptors are not known.2 D’Angelo et al. provided evidence of recapitulation of the cardiac hypertrophy gene expression by the overexpression of a single component of the stretch-activated pathway (Gαq-protein signalling pathway).3 Stretching of cardiomyocytes induces alterations in multiple pathways in myocyte biology in parallel, including sarcomeric changes, cytoskeletal proteins and mitochondria.

LV remodelling is classified based on the patterns of structural changes relative to normal (defined as normal LV mass [LVM] with normal mass-to-cavity [M-C] ratio): concentric remodelling (normal LVM with high M-C ratio); eccentric hypertrophy (high LVM with normal M-C ratio), typically observed with volume overload; and concentric hypertrophy (high LVM with high M-C ratio), typically observed with pressure overload.4 Studies have proposed that a transition may exist between early ‘compensatory’ cardiac hypertrophy in the setting of prolonged and continuous pressure overload to a ‘decompensated state’ that leads to heart failure (HF).5,6 However, emerging epidemiological studies suggest that this transition from concentric hypertrophy to HF does not occur in humans.7,8 Also, the transition from concentric LV geometry to eccentric hypertrophy occurs in <10% of patients during long-term follow-up, suggesting that the concept of using extreme pressure overloads to produce eccentric hypertrophy to understand the biology of cardiac remodelling is not clinically relevant.

Drazner et al. proposed multiple potential pathways for the progression from hypertension (classic disease of pressure overload) to HF. He showed that concentric hypertrophy progresses to dilated cardiac failure most commonly via an interval MI.9 Interestingly, clinical evidence shows that the concomitant occurrence of hypertensive and ischaemic heart disease may lead to the development of HF.10,11 Hence, Weinheimer et al. developed a surgical approach that combined transverse aortic constriction (TAC; mimicking pressure overload) and distal left anterior coronary ligation (inducing MI) to produce a gradual and predictable progression of maladaptive LV remodelling that leads to HF.12 Importantly, in this surgical mouse model, a small apical infarct (<25% infarct size) or moderate TAC alone did not lead to LV remodelling. In essence, this novel mouse model demonstrated that pressure overload acts synergistically with tissue injury to provoke LV remodelling. Dr Mann briefly discussed how tissue injury leads to LV remodelling. The inflammation initiated by tissue injury activates matrix metalloproteases, which prime the extracellular matrix to receive the increased haemodynamic load signal, leading to LV remodelling.13

This led to the question of how reverse LV remodelling happens. Dr Mann’s research team developed a murine model wherein mice develop LV remodelling after TAC and a small apical MI undergo reverse LV remodelling after removal of the aortic band at 2 weeks post-TAC/MI.14 De-banding normalised LV volumes, LV mass and cardiac myocyte hypertrophy at 6 weeks with no difference in myofibrillar collagen with or without de-banding. LV ejection fraction (LVEF) and radial strain improved after de-banding; however, both remained decreased in the de-banded mice relative to sham and were not different from non-de-banded mice at 6 weeks. Haemodynamic unloading in the de-banded mice was accompanied by a 35% normalisation of the HF genes at 2 weeks and 80% of the HF genes at 4 weeks.

Further, bioinformatic analyses showed that the reversal of the LV HF phenotype is accompanied by significant changes in the expression of multiple genes residing within each of the five different cardiac myocyte gene modules: extracellular matrix, integrin/cytoskeleton, sarcomere, excitation-contraction coupling and metabolism. These analyses also suggested that the changes in myocyte function precede changes in the integrin/cytoskeleton during reverse LV remodelling. Interestingly, reverse LV remodelling was not merely a reversal of the functional pathways that become dysregulated during HF. Instead, reverse LV remodelling represented the summation of the complex interactions between multiple biological networks that adopt a novel less-pathological configuration when the inciting stress is removed. This observation raises the possibility that some of the changes that occur during reverse LV remodelling confer vulnerability to a subsequent stress. This concept of ‘robust yet fragile’ may explain, at least in part, the observation that stable patients whose hearts undergo reverse LV remodelling with normalisation of LVEF continue to experience recurrent HF events.15,16

Future studies will determine whether the re-tuning of gene networks during reverse LV remodelling represents a ‘good enough solution’ to accommodate biological function, or whether it represents an example of a ‘robust yet fragile’ biological system that has been optimised to maintain robustness (i.e. homeostasis following loss of cardiac myocytes) at the expense of increased fragility (i.e. increased myocardial fibrosis).17

References

  1. Mann DL, Kent RL, Cooper G 4th. Load regulation of the properties of adult feline cardiocytes: growth induction by cellular deformation. Circ Res 1989;64:1079–90.
    Crossref | PubMed
  2. Force T, Michael A, Kilter H, Haq S. Stretch-activated pathways and left ventricular remodeling. J Card Fail 2002;8:S351–8.
    Crossref | PubMed
  3. D’Angelo DD, Sakata Y, Lorenz JN, et al. Transgenic galphaq overexpression induces cardiac contractile failure in mice. Proc Natl Acad Sci USA 1997;94:8121–6.
    Crossref | PubMed
  4. Rodriguez CJ, Diez-Roux AV, Moran A, et al. Left ventricular mass and ventricular remodeling among Hispanic subgroups compared with non-Hispanic blacks and whites: MESA (Multi-ethnic Study of Atherosclerosis). J Am Coll Cardiol 2010;55:234–42.
    Crossref | PubMed
  5. Meerson FZ. Compensatory hyperfunction of the heart and cardiac insufficiency. Circ Res 1962;10:250–8.
    Crossref | PubMed
  6. Dorn GW 2nd. The fuzzy logic of physiological cardiac hypertrophy. Hypertension 2007;49:962–70.
    Crossref | PubMed
  7. Drazner MH, Rame JH, Marino EK, et al. Increased left ventricular mass is a risk factor for the development of a depressed left ventricular ejection fraction within five years: the Cardiovascular Health Study. J Am Coll Cardiol 2004;43:2207–15.
    Crossref | PubMed
  8. Desai RV, Ahmed MI, Mujib M, et al. Natural history of concentric left ventricular geometry in community-dwelling older adults without heart failure during seven years of follow-up. Am J Cardiol 2011;107:321–4.
    Crossref | PubMed
  9. Drazner MH. The progression of hypertensive heart disease. Circulation 2011;123:327–34.
    Crossref | PubMed
  10. Kenchaiah S, Pfeffer MA, St John Sutton M, et al. Effect of antecedent systemic hypertension on subsequent left ventricular dilation after acute myocardial infarction (from the Survival and Ventricular Enlargement trial). Am J Cardiol 2004;94:1–8.
    Crossref | PubMed
  11. Richards AM, Nicholls MG, Troughton RW, et al. Antecedent hypertension and heart failure after myocardial infarction. J Am Coll Cardiol 2002;39:1182–8.
    Crossref | PubMed
  12. Weinheimer CJ, Lai L, Kelly DP, Kovacs A. Novel mouse model of left ventricular pressure overload and infarction causing predictable ventricular remodelling and progression to heart failure. Clin Exp Pharmacol Physiol 2015;42:33–40.
    Crossref | PubMed
  13. Weber KT, Brilla CG, Janicki JS. Myocardial remodeling and pathologic hypertrophy. Hosp Pract (Off Ed) 1991;26:73–80.
    Crossref | PubMed
  14. Weinheimer CJ, Kovacs A, Evans S, et al. Load-dependent changes in left ventricular structure and function in a pathophysiologically relevant murine model of reversible heart failure. Circ Heart Fail 2018;11:e004351.
    Crossref | PubMed
  15. Carlson JM, Doyle J. Highly optimized tolerance: a mechanism for power laws in designed systems. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1999;60:1412–27.
    Crossref | PubMed
  16. Kitano H. Towards a theory of biological robustness. Mol Syst Biol 2007;3:137.
    Crossref | PubMed
  17. Weiss JN, Karma A, MacLellan WR, et al. “Good enough solutions” and the genetics of complex diseases. Circ Res 2012;111:493–504.
    Crossref | PubMed
Impella Mechanical Circulatory Support for Takotsubo Syndrome with Shock

Takotsubo syndrome (TS) is an acute heart failure syndrome with severely depressed left ventricular ejection fraction (LVEF) and increased left ventricular end-diastolic pressure, demonstrating the severe combined systolic and diastolic failure. Dr Napp described how TS is often misdiagnosed as acute coronary syndrome, as about 75% of patients present with angina and about 50% present with ST-segment elevation.1 Both the short- and long-term prognosis is poor, with about 10% of patients developing cardiogenic shock (CS) and death in about 4%.1,2 Catecholamine release is considered to play a causal role in TS, as it may aggravate outflow tract obstruction. Therefore, the management of TS with CS is often difficult because first-line therapies for CS are often inotropes and vasopressors, acutely worsening the severity of the disease.3,4 Of note, the systolic function in TS often recovers as long as the shock is survived, that is, patients can be bridged to recovery. Thus, temporary mechanical circulatory support devices are an attractive option for therapy.5–7 However, veno-arterial extracorporeal membrane oxygenation increases afterload with limited myocardial recovery, while intra-aortic balloon pump induces or aggravates left ventricular outflow tract obstruction in TS.

Dr Napp hypothesised that Impella support is effective as a bridge to recovery in TS-related CS. His team identified TS patients supported with Impella in Europe and the US, and analysed patient characteristics and in-hospital outcomes.

A total of 20 TS patients supported with an Impella pump (six with Impella 2.5, 13 with Impella CP and one with Impella 5.0) from 10 centres in Europe and the US were identified (age 61.5 ± 17.1 years, 80% female). Eleven patients had an apical TS type and seven patients had a physical trigger. Patients were on multiple catecholamines prior to Impella (average of 2.3 ± 0.6) and had a mean systolic blood pressure of 100.5 ± 25.4 mmHg. Most patients (88.9%) were mechanically ventilated, and 38.9% sustained cardiac arrest requiring cardiopulmonary resuscitation prior to Impella. Of the 20 patients, 16 (80%) survived to discharge, with two of the non-survivors dying from causes unrelated to shock. Patients experienced myocardial recovery with a significant improvement of LVEF at discharge compared to baseline (22.5% ± 11.0% on admission versus 55.0% ± 4.8% before discharge, p<0.001).

This is the first case series to report the use of mechanical support with the Impella ventricular assist device in patients with TS. Despite the presence of refractory CS in the majority of patients, Impella support was associated with survival of 80% and myocardial recovery in surviving patients. Additional prospective studies on Impella support in TS with shock are needed to avoid the use of catecholamines and to increase survival.

References

  1. Templin C, Ghadri JR, Napp LC. Takotsubo (stress) cardiomyopathy. N Engl J Med 2015;373:2689–91.
    Crossref | PubMed
  2. Napp LC. The risk of takotsubo syndrome: seeing the light. JACC Heart Fail 2019;7:155–7.
    Crossref | PubMed
  3. Wittstein IS. The sympathetic nervous system in the pathogenesis of takotsubo syndrome. Heart Fail Clin 2016;12:485–98.
    Crossref | PubMed
  4. Rihal CS, Naidu SS, Givertz MM. 2015 SCAI/ACC/HFSA/STS clinical expert consensus statement on the use of percutaneous mechanical circulatory support devices in cardiovascular care. J Am Coll Cardiol 2015;65:e7–26.
    Crossref | PubMed
  5. Napp LC, Bavendiek U, Tongers J, et al. Dynamic left ventricular outflow tract obstruction: hemodynamic pitfall ahead. Acute Card Care 2013;15:76–7.
    Crossref | PubMed
  6. Napp LC, Kühn C, Hoeper MM, et al. Cannulation strategies for percutaneous extracorporeal membrane oxygenation in adults. Clin Res Cardiol 2016;105:283–96.
    Crossref | PubMed
  7. Napp LC, Bauersachs J. Triple cannulation ECMO. In: Firstenberg MS (ed). Extracorporeal Membrane Oxygenation – Advances in Therapy. London: IntechOpen, 2016.
    Crossref
Cardiac Unloading and the Kidney Cross-talk in Real Time

Dr Kapur began by highlighting the impact of kidney injury on long-term outcomes in patients after acute MI (AMI). The study by Parikh et al. in 2008 showed that the long-term implications of mild acute kidney injury (AKI) in the setting of AMI are striking, with only about 20% of patients surviving to 10 years.1 Also, severe AKI was associated with high mortality as early as 30 days. Another study by Goldberg et al. showed that even transient AKI after AMI is associated with a high probability of death in the long term.2 The recent study by Chalikias et al. further emphasised the significantly higher mortality within 30 days in patients developing AKI after AMI than in those without AKI, which continued for more than 10 years.3

The underlying pathophysiological mechanisms in AKI is best validated in the heart failure model. The main determinants of decreased estimated glomerular filtration rate (eGFR) are a decrease in renal blood flow (RBF) and an increase in central and renal venous pressure.4 The latter can be caused by intravascular congestion. Owing to increased renal venous pressure, renal interstitial pressure rises, resulting in the collapse of renal tubules, thus decreasing the eGFR. This eventually leads to decreased urine output, sodium retention and kidney congestion. Decreased RBF and low blood pressure trigger renal autoregulation, preserving the glomerular filtration rate by increasing the filtration fraction by increased efferent vasoconstriction. The use of certain drugs in heart failure may inhibit this efferent vasoconstriction, which leads to an increase in RBF, but may also result in a reduction in the eGFR (pseudo-worsening renal function).

Since several haemodynamic parameters influence kidney function, Dr Kapur’s research team is interested in investigating the effect of acute mechanical circulatory support devices, such as Impella and veno-arterial extracorporeal membrane oxygenation (VA-ECMO) on renal blood flow and function. The study by Abadeer et al. showed that there is a 60% incidence of AKI in patients receiving VA-ECMO for cardiogenic shock, which also correlated with poor survival.5 Patients who had severe AKI after initiation of VA-ECMO had lower survival than those with non-severe AKI. Villa et al. postulated that AKI with VA-ECMO might be related to haemodynamic, hormonal and patient-specific variables, leading to a reduction in renal oxygen delivery and/or inflammatory damage.6

A recent study by Flaherty et al. was the first to demonstrate renal protection by Impella 2.5 compared to no support in high-risk percutaneous coronary intervention patients.7 Impella 2.5 support was independently associated with a significant reduction in the risk of developing AKI during high-risk percutaneous coronary intervention. Furthermore, unpublished results from Dr Westenfeld’s research group shows that peri-interventional serum creatinine levels are stable only with Impella compared to VA-ECMO. Previously, Møller-Helgestad et al. compared the RBF with intra-aortic balloon pump (IABP) versus Impella 2.5.8 The results suggest a signal of higher RBF with Impella 2.5 and no change with IABP support.

To understand haemodynamics in the kidney, researchers at Dr Kapur’s laboratory performed pressure and flow measurements in the renal artery, renal vein and inside the renal parenchyma in the large animal, closed-abdomen experimental setup. The renal module setup was validated in healthy adult pigs treated with sham, Impella or VA-ECMO, followed by the measurement of cardiac and kidney haemodynamics over 6 hours. Preliminary results suggest that in the sham control animals, cardiac output and stroke volume (SV) were maintained over 6 hours, whereas the systemic vascular resistance (SVR) gradually declined. Treatment with Impella almost paralleled sham control animals. In contrast, the cardiac output and SV of the native heart dropped following initiation of VA-ECMO, along with a significant drop in SVR within 1 hour, which persisted throughout the treatment duration.

Dr Kapur introduced the concept that the reduction in kidney function may also be related to the role of the kidney as a sensor of damage- and pathogen-associated molecular patterns, culminating in a massive decline of function in diseases, such as sepsis.9 AKI can be characterised using functional markers, such as creatinine and urine output, and biomarkers of kidney damage, such as neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1).10 This raised the question if any insight into AKI using biomarkers of kidney damage can be gained from the pre-clinical models of AMI supported with Impella or VA-ECMO. To address this question, adult male swine were subjected to left anterior descending artery occlusion for 90 minutes, followed by either immediate reperfusion (IRI), ventricular unloading with Impella for 30 minutes prior to reperfusion while on support, VA-ECMO support for 30 minutes prior reperfusion while on support or sham-operated controls (n=4/group). Renal injury biomarkers, KIM-1 and NGAL, were measured in urine, and plasma sample was collected at different time points throughout the study. The results showed that the urinary KIM-1 levels were elevated in the IRI and VA-ECMO groups, but not the Impella group. No changes in plasma KIM-1 levels were observed in any group. Compared to baseline values, VA-ECMO increased urinary NGAL levels, but Impella did not. Compared to IRI, Impella reduced plasma NGAL levels after reperfusion.

The mechanism for increased urinary levels of KIM-1 with VA-ECMO and IRI was investigated. The protein expression for both the cytoplasmic tail fragment and the extracellular domain (ECD) of KIM-1 was measured by western blot. Compared to sham and Impella, IRI and VA-ECMO had reduced levels of the ECD, but higher levels of cytoplasmic tail of KIM-1 within the renal cortex. KIM-1 is a known substrate of metalloproteinases (MMP). Higher levels of MMP-9 expression were observed in the IRI and VA-ECMO groups than the sham and Impella groups, both in the renal cortex and left ventricular infarct zone, suggesting cross-talk between the left ventricle and renal cortex. These results also suggest that IRI and VA-ECMO activate MMP activity and promote the shedding of the ECD of KIM-1 from the renal cortex, whereas Impella does not.

In conclusion, the results indicate there may be cross-talk between the heart and the kidney after an AMI via inflammatory pathways, and Impella support prior to reperfusion attenuates this effect. It would be interesting to assess the levels of the biomarkers of kidney injury in patients treated with Impella versus no support in the ST-elevation MI Door-To-Unload pivotal study.

References

  1. Parikh CR, Coca SG, Wang Y, et al. Long-term prognosis of acute kidney injury after acute myocardial infarction. Arch Intern Med 2008;168:987–95.
    Crossref | PubMed
  2. Goldberg A, Kogan E, Hammerman H, et al. The impact of transient and persistent acute kidney injury on long-term outcomes after acute myocardial infarction. Kidney Int 2009;76:900–6.
    Crossref | PubMed
  3. Chalikias G, Serif L, Kikas P. Long-term impact of acute kidney injury on prognosis in patients with acute myocardial infarction. Int J Cardiol 2019;283:48–54.
    Crossref | PubMed
  4. Damman K, Tang WH, Testani JM, McMurray JJ. Terminology and definition of changes renal function in heart failure. Eur Heart J 2014;35:3413–6.
    Crossref | PubMed
  5. Abadeer AI, Kurlansky P, Chiuzan C, et al. Importance of stratifying acute kidney injury in cardiogenic shock resuscitated with mechanical circulatory support therapy. J Thorac Cardiovasc Surg 2017;154:856–64.e4.
    Crossref | PubMed
  6. Villa G, Katz N, Ronco C. Extracorporeal membrane oxygenation and the kidney. Cardiorenal Med 2015;6:50–60.
    Crossref | PubMed
  7. Flaherty MP, Pant S, Patel SV, et al. Hemodynamic support with a microaxial percutaneous left ventricular assist device (Impella) protects against acute kidney injury in patients undergoing high-risk percutaneous coronary intervention. Circ Res 2017;120:692–700.
    Crossref | PubMed
  8. Møller-Helgestad OK, Poulsen CB, Christiansen EH, et al. Support with intraaortic balloon pump vs. Impella2.5® and blood flow to the heart, brain and kidneys – an experimental porcine model of ischaemic heart failure. Int J Cardiol 2015;178:153–8.
    Crossref | PubMed
  9. Gomez H, Ince C, De Backer D, et al. A unified theory of sepsis-induced acute kidney injury: inflammation, microcirculatory dysfunction, bioenergetics, and the tubular cell adaptation to injury. Shock 2014;41:3–11.
    Crossref | PubMed
  10. Basile DP, Bonventre JV, Mehta R, et al. Progression after AKI: understanding maladaptive repair processes to predict and identify therapeutic treatments. J Am Soc Nephrol 2016;27:687–97.
    Crossref | PubMed
Impact of Microaxillar Mechanical Ventricular Support on Renal Resistive Index in Patients with Cardiogenic Shock after MI

Dr Schieffer began by stating that his institution adopted a regionalised system of care in 2013, along the lines of the National Cardiogenic Shock Initiative.1 The results of this initiative showed that networking improves patient outcomes. His institution also established one of the first cardiac arrest centres in Germany. As part of this initiative, 2,117 patients with out-of-hospital cardiac arrest between January 2013 and August 2019 were medically transported over a distance (range 23–97 km) and admitted to their institution. The overall survival was about 45% at 6 months and about 42% at 12 months. Among the 426 patients with post-cardiac arrest cardiogenic shock (CS) receiving Impella, the initiation of support pre-percutaneous coronary intervention (PCI) resulted in lower levels of lactate and lower vasoactive scores over 6–72 hours than post-PCI support. In addition, Impella support pre-PCI was associated with higher survival, a greater increase in left ventricular ejection fraction at 72 hours after support initiation and lower levels of creatinine (indicative of end-organ function).

Based on the above results, Dr Schieffer’s team investigated whether Impella improves renal perfusion in CS. The renal resistive index (RRI) has been studied to gain diagnostic and prognostic insights into a variety of renal pathologies (such as the progression of chronic kidney disease and renal allograft rejection), but also for the prediction of renal outcomes in critically ill patients.2,3 Therefore, Dr Schieffer’s team evaluated if RRI, determined by intrarenal artery Doppler measurements, can serve as an indicator of haemodynamics during Impella support.

RRI, measured as the quotient of (peak systolic velocity − end-diastolic velocity)/peak systolic velocity, was obtained in 15 patients with CS supported with an Impella between May and October 2018 using Doppler ultrasound.4 Simultaneously, blood pressure was determined invasively in the radial artery. RRI was determined in both kidneys in 13 patients and one kidney in two patients. The mean difference between right and left RRI was 0.026 ± 0.023 (p=0.72). When the Impella support was increased by a mean of 0.44 l/min (± 0.2 l/min), the systolic or diastolic blood pressure remained unchanged, whereas RRI decreased significantly from 0.66 ± 0.08 to 0.62 ± 0.06 (p<0.001) consistently in all patients, implying normalisation of renal perfusion.

This observation is consistent with the notion that Impella support may promote renal protection by enhancing renal perfusion. The RRI measurement serves as an early, easy and fast method for monitoring kidney function. The early detection of kidney hypoperfusion aids in prompt initiation of therapeutic manoeuvres, which are not possible when using alternative markers of acute kidney injury, such as low urine output or serum creatinine levels.

In closing, Dr Schieffer mentioned two ongoing studies investigating RRI-guided Impella treatment in high-risk PCI and CS due to acute MI.

References

  1. Tehrani BN, Truesdell AG, Sherwood MW et al. Standardized team-based care for cardiogenic shock. J Am Coll Cardiol 2019;73:1659–69.
    Crossref | PubMed
  2. Radermacher J, Chavan A, Bleck J, et al. Use of Doppler ultrasonography to predict the outcome of therapy for renal-artery stenosis. N Engl J Med 2001;344:410–7.
    Crossref | PubMed
  3. Le Dorze M, Bouglé A, Deruddre S, et al. Renal Doppler ultrasound: a new tool to assess renal perfusion in critical illness. Shock 2012;37:360–5.
    Crossref | PubMed
  4. Markus B, Patsalis N, Chatzis G et al. Impact of microaxillar mechanical left ventricular support on renal resistive index in patients with cardiogenic shock after myocardial infarction. Eur Heart J Acute Cardiovasc Care 2019; epub ahead of press.
    Crossref | PubMed
Prolonged Impella: Mode of Action and Clinical Implications

Patients with myocarditis may present with severe unexplained acute new-onset heart failure (HF). The specific causes and extent of inflammation are associated with varied prognosis. Acute fulminant myocarditis has a moderate prognosis, while giant cell and eosinophilic myocarditis have poor prognoses.1,2 The known pathophysiological processes underlying myocarditis include pro-inflammatory and fibrotic processes that lead to cardiac remodelling and failure.

In an overloaded myocardium, such as during acute fulminant myocarditis, mechanical stress activates integrins (mechanoreceptors) in the heart, which are known to mediate pro-inflammatory and fibrotic processes. Furthermore, integrins are known to have direct detrimental effects on the contractile apparatus. These combined effects exacerbate myocarditis and contribute to the poor outcomes. This raises the question if haemodynamically unloading the heart by using mechanical circulatory support (thereby decreasing mechanical stress) is sufficient to overcome a severe cardiac inflammatory response.

Several case reports of the successful short-term use of Impella pumps in fulminant and giant cell myocarditis have been published.3–7 Dr Tschöpe presented the case of an HIV-positive patient in cardiogenic shock (CS) due to viral-negative fulminant myocarditis, proven by endomyocardial biopsy. The patient was treated with temporary mechanical unloading using an Impella CP in the absence of immunosuppressive therapy.

The Impella CP support for >20 days resulted in the improvement of left ventricular ejection fraction (LVEF) to 40% from a baseline of <10%. Furthermore, Impella CP support in the absence of immunosuppressive support led to a significant drop in the mRNA expression of the integrins and innate immune cells. This was paralleled by the decrease in immune cell infiltration and an increase in protein kinase A and G activity (decreased left ventricular stiffness).

Dr Tschöpe further hypothesised that prolonged unloading with an Impella device (PROPELLA) might offer the circulatory support and disease-modifying effects that are important for bridging patients with fulminant myocarditis to recovery. This hypothesis was tested in a 62-year-old patient admitted with severe myocarditis and pre-CS, despite immunosuppressive therapy. An axillary Impella 5.0 was implanted, which remained in place for 40 days. The patient was mobilised after 2 days of Impella 5.0 support. Steroid therapy and ventricular unloading led to a significant improvement in LVEF from day 5 after initiation of support. After 4 weeks, an echocardiogram showed the first signs of recovery. Serial left ventricular biopsies were taken at various time points during treatment to assess biomarkers of inflammation.

These data demonstrate that the inflammatory response was significantly reduced during concomitant treatment with Impella and immunosuppression. However, the inflammatory response significantly increased after removal of the Impella support, despite continued immunosuppression, indicating that ventricular unloading mitigates inflammation independent of immunosuppression. The patient was weaned off Impella support after 2 months and continued immunosuppressive therapy alone. However, the immunosuppressive therapy had to be stopped early due to the development of a life-threatening abscess. The patient developed recurrent myocarditis and CS and was bridged to a long-term left ventricular assist device (LVAD). Interestingly, unloading using an LVAD also led to a decrease in immune cell presence. This case provides proof of concept that unloading improves inflammation-induced remodelling.

Dr Tschöpe presented the case of another patient with fulminant myocarditis and severe impairment of the right ventricle (RV) and left ventricle (LV). The patient received concomitant therapy with extracorporeal membrane oxygenation (ECMO) and Impella (ECMELLA).8 The RV function improved over time resulting in weaning of the patient from ECMO, whereas the Impella support was continued (PROPELLA). Again, serial LV biopsies showed a significant decrease in integrins and immune cell presence with PROPELLA support, and this effect was maintained by providing additional immunosuppressive therapy after the Impella's removal. This result suggests that additional pharmacological intervention is needed after cessation of unloading to maintain the immune-modulating effect until total myocardial recovery. Also, these results provide evidence of correlation between mechanical unloading (decrease in LV pressures) with molecular unloading (decrease in integrins).

Dr Tschöpe also presented a case of PROPELLA support in end-stage dilated cardiomyopathy without severe inflammation. In this case, the LV function did not improve with or without unloading with Impella. In addition, the mRNA expression level of integrins and immune cell presence increased, suggesting a mismatch of molecular and mechanical unloading. The failure of molecular recovery correlated with the persistence of HF, and the patient was bridged to an LVAD. This result suggests that a mismatch of mechanical and molecular unloading correlates with no myocardial recovery.

In conclusion, experience to date suggests that the PROPELLA approach in fulminant myocarditis can serve as a bridge to recovery, due to the correlation of mechanical unloading with molecular unloading, with the maintenance of these immune-modulating effects using additional pharmacological immunosuppression therapy until total myocardial recovery. In contrast, the PROPELLA approach in end-stage dilated cardiomyopathy can serve as a bridge to LVAD due to the mismatch of mechanical unloading with molecular unloading, leading to persistent HF with no myocardial recovery.

References

  1. Cooper LT Jr, Berry GJ, Shabetai R. Idiopathic giant-cell myocarditis – natural history and treatment. Multicenter Giant Cell Myocarditis Study Group investigators. N Engl J Med 1997;336:1860–6.
    Crossref | PubMed
  2. Magnani JW, Danik HJ, Dec GW Jr, DiSalvo TG. Survival in biopsy-proven myocarditis: a long-term retrospective analysis of the histopathologic, clinical, and hemodynamic predictors. Am Heart J 2006;151:463–70.
    Crossref | PubMed
  3. Andrade JG, Al-Saloos H, Jeewa A, et al. Facilitated cardiac recovery in fulminant myocarditis: pediatric use of the Impella LP 5.0 pump. J Heart Lung Transplant 2010;29:96–7.
    Crossref | PubMed
  4. Fox H, Farr M, Horstkotte D, et al. Fulminant myocarditis managed by extracorporeal life support (Impella® CP): a rare case. Case Rep Cardiol 2017;2017:9231959.
    Crossref | PubMed
  5. Narain S, Paparcuri G, Fuhrman TM, et al. Novel combination of Impella and extra corporeal membrane oxygenation as a bridge to full recovery in fulminant myocarditis. Case Rep Crit Care 2012;2012:459296.
    Crossref | PubMed
  6. Suradi H, Breall JA. Successful use of the Impella device in giant cell myocarditis as a bridge to permanent left ventricular mechanical support. Tex Heart Inst J 2011;38:437–40.
    PubMed
  7. Perry P, David E, Atkins B, et al. Novel application of a percutaneous left ventricular assist device as a bridge to transplant in a paediatric patient with severe heart failure due to viral myocarditis. Interact Cardiovasc Thorac Surg 2017;24:474–6.
    Crossref | PubMed
  8. Tschöpe C, Van Linthout S, Klein O, et al. Mechanical unloading by fulminant myocarditis: LV-IMPELLA, ECMELLA, BI-PELLA, and PROPELLA concepts. J Cardiovasc Transl Res 2019;12:116–23.
    Crossref | PubMed
Long-term Support Using Surgically Implanted Impella Devices

Dr Bernhardt began by reminding the audience of the features of the Impella 5.0. This device is an established transaortic axial flow ventricular assist device capable of providing forward blood flow of up to 5 l/min. It was originally designed for femoral access, but axillary access is increasingly used, as it allows for mobilisation of the patient. Recently, a published meta-analysis of Impella 5.0 reported favourable survival outcomes and high rates of myocardial recovery in patients with cardiogenic shock.1 The clinical uses of the surgically implanted Impella 5.0 include haemodynamic support for cardiogenic shock, safer weaning from extracorporeal membrane oxygenation (ECMO) devices, bridge-to-bridge (pre-left ventricular assist device and pre-heart transplant), bridge-to-recovery (myocarditis and peripartum cardiomyopathy) and controlled post-cardiotomy (mitral/aortic valve surgery, coronary artery bypass graft [CABG]/off-pump CABG with ejection fraction <20%).

Impella 5.0 has CE approval in Europe for a maximum 10 days of support. However, >70% of patients at Dr Bernhardt’s hospital require Impella 5.0 support for >10 days. Potential problems associated with longer duration of Impella 5.0 support include in-growth of the pigtail catheter, pump thrombosis and arterial embolisation, due to the presence of a repositioning sheath in the axillary artery.

The Impella 5.5 was developed to address both the need for a longer duration of support and to avoid the complications associated with the Impella 5.0. It is designed to provide haemodynamic support for up to 30 days. Like the Impella 5.0, the Impella 5.5 device is an axial flow transaortic cardiac support device mounted on a 9 Fr steering catheter with a 21 Fr pump cannula. The pump itself is shorter and stiffer than the Impella 5.0. Other improved features in the Impella 5.5 include an optical aortic pressure sensor distal to the outflow of the device and no pigtail at the tip of the catheter (eliminating the risk for in-growth of the pigtail and reducing the risk of thromboembolism and stroke) and improved kink resistance of the cannula. Importantly, the device provides a higher maximum pump flow of up to 5.8 l/min. The device is designed for axillary insertion and the repositioning sheath does not extend into the artery. In addition, modification of the motor size (37% shorter motor housing and the outlet area) improves deliverability. Other modifications in the motor include a modified interior for long-term durability and low purge flows.

Dr Bernhardt mentioned that the first-in-man experience with the new Impella 5.5 in two critically ill patients was performed at his institution.2 His experience is that the device is easier to implant and reposition. Until April 2019, a total of 32 patients at five German hospitals received Impella 5.5, with a survival rate of 68%.

Dr Bernhardt presented the case of a 63-year-old man receiving Impella 5.5 for post-cardiotomy failure. He had undergone aortic valve replacement (AVR) with a biological valve about 10 years earlier. The replacement valve had deteriorated and had an aortic valve opening of 0.8 cm2. At presentation, the patient had a left ventricular ejection fraction (LVEF) of 26% and left ventricular end-diastolic diameter (LVEDD) of 68 mm. The patient underwent repeat AVR with a Perimount Magna ease valve of 23 mm. Due to the inability to wean him off the cardiopulmonary bypass machine, the surgical team placed an Impella 5.5. The patient was successfully extubated 4 hours after the surgery; he was fully mobile on postoperative day 1 and Impella 5.5 was weaned and explanted under anaesthesia on day 8. At discharge, the patient had an LVEF of 35% and LVEDD of 60 mm.

Dr Bernhardt also mentioned that his institution was the first in Europe to use the Impella Connect, a cloud-based, remote-monitoring platform. The Impella Connect enables hospital clinicians and staff, along with Abiomed’s clinical support team, to view the Automated Impella Controller screen (showing ventricular pressure and Impella alarms, if any) through a secure website, allowing them to track, review and share that information from any internet-capable phone, tablet or computer.

He highlighted the new heart allocation system in the US that prioritises patients supported by temporary mechanical circulatory support (TMCS) devices, such as ECMO, over those with durable, continuous-flow left ventricular assist devices, which may increase the number of patients bridged to transplant with TMCS.3 Furthermore, a recent study by Yin et al. showed that the survival is lowest among patients bridged to transplant with ECMO compared with durable left ventricular assist devices.4 Dr Bernhardt proposed that the Impella 5.5 device may have beneficial outcomes after transplantation compared to ECMO, and should be considered for the potential lower adverse events and mortality rates during short-term device therapy on the waiting list.5

In conclusion, the Impella 5.5 expands the spectrum of available short-term mechanical circulatory support devices. New technical design features, such as the absence of pigtail, helps minimise the risk of thrombus formation, and the optical pressure sensor aids in easy pump placement and monitoring. Early experience with Impella 5.5 in patients shows promising outcomes. Future direction includes the design of the long-term bridge-to-recovery Impella heart pumps.

References

  1. Batsides G, Massaro J, Cheung A, et al. Outcomes of Impella 5.0 in cardiogenic shock: a systematic review and meta-analysis. Innovations(Phila) 2018; 13:254–60.
    Crossref | PubMed
  2. Bernhardt AM, Hakmi S, Sinning C, et al. A newly developed transaortic axial flow ventricular assist device: early clinical experience. J Heart Lung Transplant 2019;38:466–7.
    Crossref | PubMed
  3. Organ Procurement and Transplantation Network. Adult Heart Allocation Changes 2018. Available at https://optn.transplant.hrsa.gov/learn/professional-education/adult-heart-allocation (accessed 9 October 2019).
  4. Yin MY, Wever-Pinzon O, Mehra MR, et al. Post-transplant outcome in patients bridged to transplant with temporary mechanical circulatory support devices. J Heart Lung Transplant 2019;38:858–69.
    Crossref | PubMed
  5. Bernhardt AM. The new tiered allocation system for heart transplantation in the United States – a Faustian bargain. J Heart Lung Transplant 2019;38:870–1.
    Crossref | PubMed
Update from the National Cardiogenic Shock Initiative

Dr O’Neill stated the causes of cardiogenic shock (CS) that ultimately influence patient outcomes. One of the main causes of significant variation in outcomes when comparing large retrospective registries of CS is the inclusion of patients with CS following an out-of-hospital cardiac arrest (OHCA). Typically, CS after OHCA is mostly due to arrhythmia rather than ischaemia, and these patients may also have neurological injury, leading to a worse prognosis. He emphasised that the National Cardiogenic Shock Initiative (NCSI) is a standardised protocol-based approach to treat CS due to acute MI (AMICS).

Dr O’Neill further highlighted that there are no Class Ia indicated therapy for AMICS in the European Society of Cardiology 2017 guidelines. Randomised controlled trials (RCTs) are challenging in AMICS, particularly in the US, given the need to obtain informed consent. A few RCTs have been conducted in Germany, where there is a system of prospective conditional approval. Therefore, in 2016, Dr O’Neill and colleagues designed a prospective registry to assess outcomes in patients with AMICS treated with Impella based on a standardised protocol. The protocol emphasises the early initiation of Impella support prior to reperfusion in patients with AMICS.

An analysis of data from more than 15,000 AMICS patients treated with Impella in the Abiomed Impella Quality (IQ) registry suggested a wide variation in survival outcomes across centres, based on the volume of Impella use.1 Further analysis of the IQ registry identified three best practices associated with improved survival in AMICS: initiation of Impella support prior to percutaneous coronary intervention (PCI), haemodynamic monitoring using pulmonary artery catheter and the use of Impella CP. Dr O’Neill was excited about the increased adoption of these best practices over time, which was associated with a parallel increase in survival to Impella explantation from 51% in January 2009–December 2016 to 63% in April 2015–September 2018 (p<0.00001). The number of hospital sites in the registry that demonstrated a survival to explantation of >80% increased from 11% in January 2009–December 2016 to 19% in April 2015–September 2018.

The Detroit Cardiogenic Shock Initiative started in 2016 as a pilot study, with four Detroit sites agreeing to treat all patients with AMICS using a mutually agreed-upon, best-practice algorithm.2 Of the 66 screened patients, 50 were included in the single-arm, prospective, multicentre study. The survival rate was 76%, compared with 53% in the Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock (SHOCK) trial and 53% in the IMPella versus IABP Reduces mortality in STEMI patients treated with primary PCI in Severe cardiogenic SHOCK (IMPRESS in Severe Shock) trial.3,4 The initiative has continued to grow. At present, more than 65 sites around the country are using the algorithm (Figure 1) and best practices, now referred to as the NCSI (NCT03677180).

National Cardiogenic Shock Initiative: Treatment Algorithm

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As of 14 June 2019, a total of 423 patients had been screened for inclusion, of whom 214 were included in the initiative. A recent analysis of 171 patients included in the NCSI (lactate of 5.3 mmol/l and cardiac arrest in 42%) reported the survival rate of 72%.5 This survival rate is higher compared to the SHOCK trial (53%) and Intraaortic Balloon Pump in Cardiogenic Shock (IABP-SHOCK) trial (60%).3,6

Dr O’Neill highlighted that the clinical sites in the NCSI are a combination of academic (38%) and community hospitals (62%). It is important to include community hospitals because 60% of CS patients present to a community hospital. He also emphasised the vital role of the ‘hub and spoke’ model to ensure prompt care for a wide range of patients.

The revascularisation strategy among patients enrolled in the NCSI was analysed. The survival among patients with one-, two- and three-vessel disease treated with a single vessel PCI was 71%, 72% and 75%, respectively. Interestingly, the survival was not significantly different among patients treated with a single-vessel or multivessel PCI, suggesting that the revascularisation strategy does not impact survival rates in this patient population. A potential reason for this effect could be a lower incidence of contrast-induced renal dysfunction in patients supported with Impella. In contrast, >70% of patients in the Culprit Lesion Only PCI Versus Multivessel PCI in Cardiogenic Shock (CULPRIT-SHOCK) trial did not receive haemodynamic support, which is the likely cause of the different outcomes.7 In light of the above findings, Dr O’Neill suggested that the revascularisation strategy in patients with AMICS receiving haemodynamic support needs to be revisited.

Next, an attempt was made to identify important clinical and haemodynamic variables that aid in predicting outcomes post-PCI. Cardiac power output (CPO), cardiac output, cardiac index, pulmonary artery oxygen saturation, pulmonary artery pulsatility index, hepatic enzymes and lactate were found to be useful predictors of survival.5

Stratifying patients according to CPO (> or <0.6 W) and lactate (> or <4 mg/dl) at 12–24 hours post-PCI and Impella support provides a reliable and useful tool for predicting outcomes and the need for escalation of therapy. In addition, survival was lowest for patients with CPO ≤0.6 W and receiving ≥2 inotropes, while highest for patients with CPO ≥0.6 W and receiving 0–1 inotropes post-Impella and PCI.

In conclusion, the findings from the NCSI have demonstrated that a protocol-based approach emphasising best practices is reproducible in institutions across the country in both academic and community programmes and is associated with significant improvement in survival in AMICS compared to historical controls. Future studies will focus on identifying factors that will improve survival to >80% in AMICS.

References

  1. O’Neill WW, Grines C, Schreiber T, et al. Analysis of outcomes for 15,259 US patients with acute myocardial infarction cardiogenic shock (AMICS) supported with the Impella device. Am Heart J 2018;202:33–8.
    Crossref | PubMed
  2. Basir MB, Schreiber T, Dixon S, et al. Feasibility of early mechanical circulatory support in acute myocardial infarction complicated by cardiogenic shock: the Detroit cardiogenic shock initiative. Catheter Cardiovasc Interv 2018;91:454–61.
    Crossref | PubMed
  3. Hochman JS, Sleeper LA, Webb JG, et al. Early revascularization in acute myocardial infarction complicated by cardiogenic shock. (Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock?) N Engl J Med 1999;341:625–34.
    Crossref | PubMed
  4. Ouweneel DM, Eriksen E, Sjauw KD, et al. Percutaneous mechanical circulatory support versus intra-aortic balloon pump in cardiogenic shock after acute myocardial infarction. J Am Coll Cardiol 2017;69:278–87.
    Crossref | PubMed
  5. Basir MB, Kapur NK, Patel K, et al. improved outcomes associated with the use of shock protocols: updates from the National Cardiogenic Shock Initiative. Catheter Cardiovasc Interv 2019;93:1173–83.
    Crossref | PubMed
  6. Thiele H, Zeymer U, Neumann FJ, et al. Intraaortic balloon support for myocardial infarction with cardiogenic shock. N Engl J Med 2012;367:1287–96.
    Crossref | PubMed
  7. Thiele H, Akin I, Sandri M, et al. PCI strategies in patients with acute myocardial infarction and cardiogenic shock. N Engl J Med 2017;377:2419–32.
    Crossref | PubMed
Peri-procedural Ventricular Unloading with Impella Optimises Outcomes in High-risk Patients at a Community Hospital

Dr Williams noted the limited available data on the use of Impella devices during cardiac surgery. RECOVER I was a prospective pilot study of Impella 5.0/left direct for postcardiotomy cardiogenic shock (PCCS).1 The study demonstrated that safety and feasibility of the use of the Impella 5.0/left direct in PCCS with a favourable survival of 94% at 30 days. Immediately after the initiation of Impella support, cardiac index, mean arterial pressure and pulmonary artery diastolic pressure improved.

Lemaire et al. reported a single-centre study of 47 patients treated with Impella for cardiogenic shock (CS), including 32 patients with PCCS.2 Survival at 30 days was 75% and 63.8% at 1 year. Of the 35 survivors, 88% had recovery of native heart and 11% were bridged to long-term ventricular assist devices.

Dr Williams highlighted study findings suggesting early initiation of Impella support prior to percutaneous coronary intervention was associated with improved survival. This led to the hypothesis that preoperative selection of high-risk patients for placement of Impella devices to haemodynamically optimise them before surgery and assist with recovery in the immediate postoperative period should allow faster recovery, reduced intensive care unit and hospitalisation days, improved end-organ function and reduced inotropic needs immediately postoperatively.

Dr Williams tested this hypothesis at his institution, which is a community healthcare system involving two hospitals, two catheterisation laboratories and four cardiac operation theatres. The cath lab Impella programme has been available since 2014, and the surgical Impella programme started in 2017. In the surgical programme, Impella support is used in three different subsets of patients: elective insertion of Impella preoperatively, haemodynamic optimisation group receiving Impella preoperatively (patients presenting in CS receive Impella urgently to stabilise) and rescue insertion of Impella for PCCS.

The Impella device was used electively in patients based on frailty or surgeon gestalt, in addition to ejection fraction (EF) <20% and undergoing any procedure requiring cross-clamp, EF 20–30% undergoing off-pump coronary artery bypass grafting (CABG) or EF <25% undergoing major valve/CABG/double-valve procedures. Patients in the haemodynamic optimisation group receive Impella preoperatively to reverse end-organ damage, assist with diuresis and unload the ventricle while recovering from an acute event. Typical patients include those with acute MI and decompensation in need of urgent CABG and decompensated chronic heart failure with EF <25% requiring valve surgery. Impella use for PCCS was defined as ≥2 escalating doses of inotropes, inability to wean from cardiopulmonary bypass and failure to improve with an intra-aortic balloon pump.

A total of 149 patients received Impella devices at their institution. Of these, 35 patients underwent definitive surgical intervention following the initiation of Impella support; 23 patients received Impella electively, while 12 received Impella urgently. Patients receiving elective Impella support had a lower EF (19% ± 5%) compared to those receiving urgent Impella support (39% ± 17%). About 25% of patients in the elective group received high-dose inotropes, compared to 0% in the urgent group. The overall 30-day mortality was 9%, with no difference between the elective versus urgent Impella groups. The postoperative mortality was higher among patients with end-organ dysfunction, such as kidney or liver failure. There was a trend towards higher utilisation of blood products in patients receiving Impella CP versus Impella 5.0.

In conclusion, the results suggest that high-risk cardiac surgery with Impella support is safe, feasible and effective in the community hospital setting. Also, preoperative identification of high-risk patients who may benefit from left ventricular unloading with Impella is possible. Additional data might permit the development of a selection algorithm that would be broadly applicable to optimise outcomes in patients undergoing high-risk cardiac surgery.

References

  1. Griffith BP, Anderson MB, Samuels LE, et al. The RECOVER I: a multicenter prospective study of Impella 5.0/LD for postcardiotomy circulatory support. J Thorac Cardiovasc Surg 2013;145:548–54.
    Crossref | PubMed
  2. Lemaire A, Anderson MB, Lee LY, et al. The Impella device for acute mechanical circulatory support in patients in cardiogenic shock. Ann Thorac Surg 2014;97:133–8.
    Crossref | PubMed
Longitudinal Impact of Temporary Mechanical Circulatory Support on Durable Ventricular Assist Device Outcomes: An IMACS Registry Analysis

Dr Hernandez-Montfort began by stating that acute heart failure (AHF) with cardiogenic shock (CS) remains a complex, heterogenous and time-sensitive disease entity that continues to challenge healthcare systems across the globe.1,2 He drew attention to the fact that escalating doses of inotropes in AHF with CS are associated with exponential mortality.3 He noted that contemporary care in AHF complicated with CS includes the use of temporary circulatory support (TCS) as a therapeutic bridge strategy that can potentially aid the transition to replacement therapies, such as durable ventricular assist devices (dVAD).2

There are limited data characterising longitudinal transitions for patients with AHF and CS receiving TCS prior to dVAD, despite its increased utilisation.4,5 Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) patient profiles 1–3 are commonly utilised, although they also have shown to be heterogeneous descriptors of severity of illness prior to dVAD.6 Hence, it is unclear whether a preimplant TCS strategy affects short- and long-term survival after dVAD. Also, specific TCS device/phenotype associated with recovery, replacement or palliation are yet to be characterised.

The aim of Dr Hernandez-Montfort’s study was to describe the global epidemiology of patients receiving TCS (defined as preoperative use of extracorporeal membrane oxygenation [ECMO], intra-aortic balloon pump [IABP] and other TCS, including Centrimag, Impella and Tandem Heart) before durable left ventricular assist device (LVAD) implantation. In addition, to examine the short- and long-term survival of patients receiving TCS patients versus those not receiving TCS.

A total of 16,754 adult patients were implanted with dVAD in the International Society for Heart and Lung Transplantation Registry for Mechanically Assisted Circulatory Support (January 2013–November 2017). Of these, 13,813 patients had INTERMACS patient profile 1–3 and received a continuous flow LVAD (CF-LVAD) or biventricular assist device (BiVAD). A total of 5,632 patients received preoperative TCS before receiving CF-LVADs or BiVADs, while 7,879 belonged to the non-TCS group. The TCS support was classified as ECMO (1,138), IABP (3,901) and other TCS (593).

ECMO was used as TCS prior to dVAD mainly in Europe (17%), followed by Asia-Pacific (9%) and the Americas (8%). IABP was used mostly in the Americas (31%), followed by Asia-Pacific (26%) and Europe (11%). Other TCS was used mostly in Asia-Pacific (13%), with similar utilisation in the Americas and Europe (4% each). The majority of patients receiving ECMO (77.6%) had INTERMACS profile 1. However, only 20.5% were bridged to transplant. All patients who received TCS had signs of right and left heart loading conditions and myocardial impairment, whereas patients on ECMO had elevated bilirubin levels, indicating liver congestion. Also, patients on ECMO were likely to receive BiVAD (22.1%), centrifugal pump (49.1%) and concomitant surgery (77.1%). The length of intensive care unit (ICU) stay (24 days) and implant-to-discharge duration (40 days) was longer with ECMO than IABP or other TCS support.

Importantly, patients receiving TCS support had lower survival than those not receiving TCS support at 2 years. Also, patients on ECMO had lower survival compared to patients treated with IABP or other TCS support. Multivariable analysis identified ECMO (versus other TCS) to be associated with increased risk of early death (HR 2.03, p<0.0001). Also, surrogates of kidney and liver function (such as creatinine and bilirubin) and right heart load (central venous pressure) were associated with early death. Similar results were obtained in the propensity-matched cohort of ECMO versus other TCS, ECMO versus IABP and ECMO versus non-TCS.

In summary, there are regional differences in pre-implant TCS, with ECMO being more commonly used in Europe than other regions. Patients requiring pre-implant TCS had lower longitudinal survival compared to patients without TCS.

Patients with pre-implant ECMO were less likely to receive dVAD as bridge to transplant and more likely to receive BiVAD. Patients on pre-implant ECMO had the highest median ICU length of stay and the lowest median time on dVAD. Further research in patients with INTERMACS profile 1–3 transitioning to dVAD is needed to better understand the differences in survival with ECMO versus other TCS.

References

  1. Rab T. “Shock teams” and “shock docs”. J Am Coll Cardiol 2019;73:1670–2.
    Crossref | PubMed
  2. van Diepen S, Katz JN, Albert NM, et al. contemporary management of cardiogenic shock: a scientific statement from the American Heart Association. Circulation 2017;136:e232–68.
    Crossref | PubMed
  3. Samuels LE, Kaufman MS, Thomas MP, et al. Pharmacological criteria for ventricular assist device insertion following postcardiotomy shock: experience with the Abiomed BVS system. J Card Surg 1999;14:288–93.
    Crossref | PubMed
  4. Vallabhajosyula S, Arora S, Lahewala S, et al. Temporary mechanical circulatory support for refractory cardiogenic shock before left ventricular assist device surgery. J Am Heart Assoc 2018;7:e010193.
    Crossref | PubMed
  5. den Uil CA, Akin S, Jewbali LS, et al. Short-term mechanical circulatory support as a bridge to durable left ventricular assist device implantation in refractory cardiogenic shock: a systematic review and meta-analysis. Eur J Cardiothorac Surg 2017;52:14–25.
    Crossref | PubMed
  6. Cowger J, Shah P, Stulak J, et al. INTERMACS profiles and modifiers: heterogeneity of patient classification and the impact of modifiers on predicting patient outcome. J Heart Lung Transplant 2016;35:440–8.
    Crossref | PubMed
How to Unload the Heart on Extracorporeal Membrane Oxygenation

Dr Meyns stated his intention to make a case for unloading in patients receiving extracorporeal membrane oxygenation (ECMO). He emphasised the increasing utilisation of ECMO in the treatment of acute cardiogenic shock (CS) due to technical ease of implantation at the bedside, transportability, oxygenation, immediate restoration of haemodynamics and the use as a bridge to decision. The survival to discharge of patients on ECMO varies from 41% for CS to 29% for extended cardiopulmonary resuscitation.1

He highlighted that incremental improvements in oxygenators, pumps, cannulas and management strategies have significantly reduced the incidence of adverse events with ECMO. Notwithstanding, major adverse events include bleeding and increased left ventricular (LV) afterload leading to LV distension of an already failing heart.

Unloading during ECMO helps avoid pulmonary congestion, improves myocardial recovery and reduces the risk of thrombus formation.2 There are multiple strategies for unloading the failing LV during veno-arterial ECMO support, such as apical/pulmonary/transaortic drainage catheter, Impella and reducing ECMO flow. He presented multiple cases of patients unloaded with the strategies mentioned above, particularly with Impella.

Dr Meyns shared the management algorithm for acute CS at his institution. The Impella is the preferred LV unloading device before revascularisation in patients presenting with CS, defined as aortic blood pressure <90 mmHg for >30 minutes with plasma lactate > 2 mmol/l. Following revascularisation, if the cardiac index <2.5, then the escalation of therapy is considered. In patients requiring CPR or presenting with predominant right ventricular failure, ECMO is the preferred device for unloading followed by unloading with Impella, if needed.

In 2018, 31 patients with CS were treated at his institution using the management strategy mentioned above. Of these, 17 were treated with Impella alone and 14 with ECMO plus Impella. The Impella CP was implanted in 15 and Impella 5.0 in 16 patients. In the ECMO plus Impella group, nine patients died, two were bridged to left ventricular assist device (LVAD) and three had recovery. In the Impella alone group, three patients died, five were bridged to LVAD and nine had myocardial recovery. The overall survival was 61%, which is better than historical controls. The mean duration of Impella support was 8.5 days with a maximum of 38 days, which is higher than the typical ECMO support. He further highlighted the advantage of axillary access for Impella 5.0, including long-term support with the ability to mobilise the patient.

References

  1. Thiagarajan RR, Barbaro RP, Rycus PT, et al. Extracorporeal Life Support Organization Registry International Report 2016. ASAIO J 2017;63:60–7.
    Crossref | PubMed
  2. Meyns B, Stolinski J, Leunens V, et al. Left ventricular support by catheter-mounted axial flow pump reduces infarct size. J Am Coll Cardiol 2003;41:1087–95.
    Crossref | PubMed
ST-elevation MI Door-To-Unload Pivotal Trial: Acute Cardiac Unloading and Myocardial Recovery

In the concluding talk, Dr Kapur provided the rationale and discussed the trial design of the ST-elevation MI Door-To-Unload (STEMI-DTU) pivotal trial. He stated a few facts from the American Heart Association about MI and its prognosis. Nearly every 40 seconds, an American will have an MI, and the estimated annual incidence of new MI is 605,000.1 The estimated average number of years of life lost because of an MI death is 16.2. Approximately 35% of people who experience a coronary event in a given year will die as a result of it, and about 14% who experience an MI will die. He highlighted that the Swedish Web-system for Enhancement and Development of Evidence-Based Care in Heart Disease (SWEDEHEART) study shows that heart failure (HF) after MI increases mortality, and this is one of the reasons why the STEMI-DTU trial is needed.2,3 Studies have also shown that the size of the infarcts matter. For every 5% increase in myocardial infarct size, 1-year all-cause mortality increases by 19% and HF hospitalisation by 20%.4

He discussed the paradox of reperfusion therapy in MI by highlighting that reperfusion therapy to limit myocardial damage in STEMI may itself promote myocardial damage. A fundamental component of the paradox is the mandate for rapid reperfusion in STEMI.5,6 Data suggest that every 30-minute increase in ischaemic time is associated with increased 1-year mortality and infarct size. This raises the question of whether the ischaemic time increases in the STEMI-DTU trial due to delayed reperfusion in the Impella arm. Studies have suggested that during ischaemia without reperfusion, 100% of the area at risk (AAR) is infarcted.7 On the other hand, only 50% of the AAR is infarcted with ischaemia with timely reperfusion, and ischaemia with timely reperfusion with cardioprotection may reduce the infarct size to 25% of the AAR.7,8

Dr Kapur noted that the current approaches of management in STEMI have focused on reducing reperfusion injury, not ischaemic injury.9 He highlighted that left ventricle (LV) unloading with Impella uncouples ischaemia and reperfusion, thus reducing the fear of delaying reperfusion.10 He showcased the pre-clinical development of primary unloading from 2012 to 2019, which demonstrated that transvalvular LV unloading limits myocardial ischaemia and promotes a cardioprotective shift in myocardial biology.

Dr Kapur emphasised that in STEMI-DTU, delayed reperfusion is not equal to delayed treatment. He hypothesised that unloading the LV prior to reperfusion limits the potential ischaemic damage, thus the point of inhiation of haemodynamic support may be considered the onset of treatment. To test this hypothesis, adult male pigs subjected to left anterior descending artery (LAD) occlusion for 90 minutes were divided into two groups. In the no unloading group, LAD was occluded for an additional 120 minutes without reperfusion. In the unloading group, LAD was occluded for an additional 120 minutes with unloading using Impella and no reperfusion. The infarct size was 10% of the AAR in the no unloading group without reperfusion compared to 2–3% of the AAR in the unloaded group without reperfusion. Interestingly, the infarct size in the no unloading group increased from 10% to 30% of the AAR following reperfusion. Likewise, the infarct size also increased in the unloaded group from <3% to 18% of the AAR after reperfusion, but was significantly less than the no unloading group. These results suggest two important things. First, ischaemia-dependent damage is independent of reperfusion-dependent damage, and second, that unloading with Impella prior to reperfusion may differentially limit both.

The STEMI-DTU pilot trial assessing the feasibility and safety of primary LV unloading and delaying reperfusion was conducted before attempting a randomised control trial evaluating the efficacy of this approach.11 In the STEMI-DTU pilot trial, 50 patients presenting with anterior STEMI at 14 centres in the US were randomised to mechanical unloading with the Impella CP, followed by immediate reperfusion (U-IR) or LV unloading with a 30-minute delay to reperfusion (U-DR). The majority of the patients enrolled in the pilot trial had large anterior MI with high left ventricular end-diastolic pressure (LVEDP). Notably, no patient in the trial experienced no reflow after the percutaneous coronary intervention (PCI) compared to the expected rate of 25%. The successful STEMI-DTU pilot trial established safety, feasibility and compliance with no bailout PCI in the U-DR arm. A subgroup analysis of infarct size normalised to the myocardial AAR was performed in patients stratified by sum ST-segment elevation. A stepwise increase in infarct size normalised to the AAR was observed in the U-IR group compared with no such effect in the U-DR group. This result suggests that unloading and reperfusion limits infarct size, irrespective of the AAR by sum ST-segment elevation.

He further outlined the current trial design of the upcoming STEMI-DTU pivotal trial. When a patient with anterior STEMI presents to a DTU site, an iliac and femoral angiogram, LV-gram and LVEDP measurement are performed. The patients are then randomised to either the DTU arm (LV unloading with Impella CP, followed by reperfusion using PCI) or the door-to-balloon (DTB) arm (reperfusion as per current standard of care). In the DTU arm, Impella CP support is initiated first, followed by PCI. The patient will be supported with Impella CP for 4–6 hours post-PCI, and the subject will be taken to the catheterisation lab for Impella explant. In the DTB arm, patients will receive PCI after a coronary angiogram. The primary endpoint of the trial is infarct size as a percentage of LV mass at 3–5 days.

Secondary endpoints include clinical safety evaluation at 30 days, 6, 12, 18 and 24 months. The subjects will be followed up yearly until 60 months.

In conclusion, Dr Kapur emphasised that there is no delay to treatment in the STEMI-DTU trial. The biggest difference is that the treatment in STEMI-DTU begins with LV unloading with the ultimate goal to prevent HF after an acute MI by limiting infarct size and aid the process of myocardial recovery.

References

  1. Benjamin EJ, Muntner P, Alonso A, et al. Heart disease and stroke statistics – 2019 update: a report from the American Heart Association. Circulation 2019;139:e56–528.
    Crossref | PubMed
  2. Desta L, Jernberg T, Löfman I, et al. Incidence, temporal trends, and prognostic impact of heart failure complicating acute myocardial infarction. The SWEDEHEART Registry (Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies): a study of 199,851 patients admitted with index acute myocardial infarctions, 1996 to 2008. JACC Heart Fail 2015;3:234–42.
    Crossref | PubMed
  3. Gerber Y, Weston SA, Enriquez-Sarano M, et al. Mortality associated with heart failure after myocardial infarction: a contemporary community perspective. Circ Heart Fail 2016;9:e002460.
    Crossref | PubMed
  4. Stone GW, Selker HP, Thiele H, et al. Relationship between infarct size and outcomes following primary PCI: patient-level analysis from 10 randomized trials. J Am Coll Cardiol 2016;67:1674–83.
    Crossref | PubMed
  5. De Luca G, Suryapranata H, Ottervanger JP, Antman EM. Time delay to treatment and mortality in primary angioplasty for acute myocardial infarction: every minute of delay counts. Circulation 2004;109:1223–5.
    Crossref | PubMed
  6. Tarantini G, Cacciavillani L, Corbetti F, et al. Duration of ischemia is a major determinant of transmurality and severe microvascular obstruction after primary angioplasty: a study performed with contrast-enhanced magnetic resonance. J Am Coll Cardiol 2005;46:1229–35.
    Crossref | PubMed
  7. Yellon DM, Hausenloy DJ. Myocardial reperfusion injury. N Engl J Med 2007;357:1121–35.
    Crossref | PubMed
  8. Fröhlich GM, Meier P, White SK, et al. Myocardial reperfusion injury: looking beyond primary PCI. Eur Heart J 2013;34:1714–22.
    Crossref | PubMed
  9. Kapur NK, Karas RH. A new shield from the double-edged sword of reperfusion in STEMI. Eur Heart J 2015;36:3058–60.
    Crossref | PubMed
  10. Kapur NK, Qiao X, Paruchuri V, et al. Mechanical pre-conditioning with acute circulatory support before reperfusion limits infarct size in acute myocardial infarction. JACC Heart Fail 2015;3:873–82.
    Crossref | PubMed
  11. Kapur NK, Alkhouli MA, DeMartini TJ, et al. Unloading the left ventricle before reperfusion in patients with anterior st-segment-elevation myocardial infarction. Circulation 2019;139:337–46.
    Crossref | PubMed