Article

A35 - High Serum Phosphate Concentrations after ROSC in OHCA patients with MCS Indicates Favourable Outcome

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Citation:Interventional Cardiology Review 2019;14(3 Suppl 1):A35.

Correspondence: Fabian Voss, fabian.voss@med.uni-duesseldorf.de

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Background: Recent data suggest that one-third of patients meeting conventional ECG criteria for left bundle branch block (LBBB) may be misdiagnosed, and new, stricter ECG criteria for LBBB have been proposed (Strauss’ criteria). Accordingly, we used 2D speckle-tracking echocardiography to compare left ventricular mechanics in patients with LBBB according to conventional versus Strauss’ ECG criteria for LBBB.

Methods: We included consecutive adult patients reaching return of spontaneous circulation (ROSC) following out-of-hospital cardiac arrest (OHCA) in 2016 and 2017 who were transferred to University Hospital Düsseldorf for non-traumatic reasons. As a primary outcome, we compared survival to discharge grouped by high or low first serum phosphate levels after arrival (cutoffs: 2.5 and 3 mmol/l) with and without implantation of mechanical circulatory support (MCS; extracorporeal membrane oxygenation or Impella). Additionally, phosphate clearance after MCS implantation was calculated in survivors and non-survivors. Statistical analysis was performed by using Fisher’s exact test (case controls) and unpaired t-tests for detecting differences between the groups. Significance was assumed if p<0.05.

Results: We included 95 patients with a medium age of 64.7 ± 1.56 years; 66% were men and 41% had an acute MI (ST-elevation MI/non ST-elevation MI) as the assumed reason for OHCA. Baseline serum creatinine was 1.7 ± 0.12 mg/dl and baseline lactate was 8.3 ± 0.62 mg/dl. Shockable rhythm was present in 53.7% and medium time to ROSC was 22.9 ± 2.87 minutes in survivors and 40.1 ± 4.21 minutes in non-survivors (p=0.001). In 45 patients the average serum phosphate was 2.5 mmmol/l, and 22 received MCS.

As expected, in patients without MCS, initial serum phosphate concentrations were higher in non-survivors compared to survivors (3.0 ± 0.17 versus 1.8 ± 0.16 mmol/l, p<0.0001). However, in patients with MCS, elevated initial phosphate levels above 2.5 mmol/l were associated with a greater chance of survival to discharge (cutoff 2.5 mmol/l: 39% versus 9%, p=0.03; cutoff 3 mmol/l: 50% versus 9.1%, p=0.02). In the time course following MCS implantation, phosphate clearance was higher in survivors than in non-survivors when initial serum phosphate was >2.5 mmol/l (2.9 versus 1.7 mmol/l, p=0.02). Survivors and non-survivors with MCS did not differ in initial serum lactate (6.99 versus 7.53), whereas patients without MCS did (4.6 versus 10.99, p<0.001). Initial serum phosphate showed close correlation to initial serum lactate over all groups (r=0.6, p<0.0001). Survivors in both groups were younger than non-survivors.

Conclusion: In patients with ROSC following OHCA, elevated initial serum phosphate (>2.5 mmol/l) is associated with improved survival in patients with MCS. Prospective analyses will help to clarify potential mechanisms.