A symposium, chaired by Dr Heinz Joachim Büttner of Freiburg-Bad Krozingen (Germany) and Dr Masahisa Yamane of St Luke’s International Hospital (Tokyo, Japan) took place at EuroPCR, Paris on May 23rd, 2014. Its objectives were as follows: to learn how to improve the success of percutaneous intervention (PCI) in chronic total occlusion (CTO) by matching techniques to anatomical and clinical characteristics; to improve procedural skills in CTO and complex PCI by sharing experience with established operators during transmitted live cases; to understand why bioabsorbable polymer or polymer-free sirolimuseluting stents can improve long-term benefit in patients undergoing complex and CTO PCI and how to use imaging modalities to facilitate CTO recanalisation.
Chronic total occlusions remain the most challenging lesions treated by interventional cardiologists. Approximately 30 % of all coronary angiograms in patients with coronary artery disease (CAD) show a CTO.1 These represent around 24 % of the patient population treated by PCI and 22 % of those treated by coronary artery bypass graft (CABG) according to the Synergy between PCI with Taxus™ and cardiac surgery (SYNTAX) study. The majority of patients with CTO (56 %) are denied PCI and sent to surgery (see Figure 1).2 Successful recanalisation of a CTO is a strong independent predictor for reduced long-term mortality in patients with three vessel disease (3VD) but not with 1+2VD.3 In patients with multi-vessel disease and ST-elevation myocardial infarction (STEMI) undergoing primary PCI in the Harmonising outcomes with revascularisation and stents in acute myocardial infarction (HORIZONS-AMI) trial, a CTO in a non -infarctrelated artery was an independent predictor of early mortality. The presence of a CTO in a non-IRA was also an independent predictor of increased late mortality up to three years.4 A meta-analysis of randomised clinical trials and observational studies suggested that complete revascularisation is the optimal strategy in both CABG and PCI in patients with multi-vessel disease.5
Despite the improving success rates of PCI in CTO, they are still inferior compared to non-occlusive CAD. There is a great diversity in the complexity of the CTO lesion and the J-CTO (Multicenter CTO Registry of Japan) score has been developed as a model to stratify the complexity and predict expected success rates. According to that model there are four difficulty groups: easy (J-CTO score of 0), intermediate (score of 1), difficult (score of 2) and very difficult (score of ≥ 3), (see Figure 2).6 Score points were determined by assigning one point in the presence and zero in the absence of each of the following angiographic characteristics: calcification, intra CTO bending, blunt stump, occlusion length >20 mm and a previously failed lesion. Guidewire manipulation time and success rates for different J-CTO scores are shown in Figure 2.
Recanalisation techniques include the anterograde (single wire, parallel wire, intravascular ultrasound [IVUS] navigated, and their variations), the retrograde that require collateral crossing, CTO entering, wire (re)entry beyond CTO via reverse CART (controlled antegrade and retrograde tracking (CART), direct wire crossing kissing wire and their variations, and the dissection re-entry techniques that they can be used both antegrade and retrograde.
Dr Gerald Werner from the Darmstadt Hospital (Germany) discussed the importance of patient selection in the PCI of coronary CTOs. Several questions should be addressed in the assessment of whether a patient with CTO will benefit from PCI. Is the patient symptomatic in terms of angina, dyspnoea or exercise limitation? Is there evidence of a prior MI? Accordıng to the EuroCTO club consensus document, recanalization of CTOs is ındıcated ın symptomatıc patıents that have no hıstory of prevıous MI. In case of prevıous MI viability should be documented ın the area provıded by the occluded artery and the myocardium at risk should be more than 10 %.7
In terms of predicting patient benefıt, the Euro CTO recommendations state that we should treat patients with CTO as any other CAD patients, provided the operator ıs experienced enough and that that the expected success rates are ın the range of 80 %. In a metaanalysis of CTO recanalisation, successful attempts were associated with symptomatic relief.8 Ischaemic burden is also reduced following PCI of CTO, and the decrease is greater at higher ischaemic burden. Conversely, in patients wıth a lower ischaemic burden, the treatment benefıt was less consıdering the presence of potential complıcations and treatment costs related to the procedures.9 It has been suggested that in the setting of CTO, we should select patients for PCI with ischaemic burden >10 % of myocardium, to achieve certain benefit.9 Individual patient data should be always taken into account.
In multi-vessel disease and CTO, it is necessary to determine which lesion causes the symptoms, and also to obtain evidence of ischaemic burden and expected completeness of revascularisation. In the SYNTAX trıal ıncomplete revascularisation is associated with an increased rate of major cardiac and cerebrovascular events (MACCE, see Figure 3) and the presence of CTOs is an ımportant contributor to the ıncomplete revascularısatıon.10 The residual SYNTAX score ıs an angıographıc tool that can quantıtate the level of the completeness of revascularisation. A residual SYNTAX Score exceeding eight was associated with high mortality (35.3 % all-cause mortality at five-years, p<0.001).11
Current treatment paradigms suggest that one or two vessel disease favours PCI while three-vessel disease requires surgery if complete revascularisation cannot be achieved with PCI. So, what if we can achieve complete revascularisation? This needs to be built into the guidelines. The strategy of the EuroCTO club in multi-vessel disease with CTO, is a staged procedure for non-CTO first, with the goal of complete revascularisation.
Dr Nicolaus Reifart from Frankfurt, Germany, gave a presentation focussing on CTO and complex PCI procedures. Before undertaking PCI, all risks need to be addressed, and other options such as optimal medical therapy should be considered. Case selection should also be tailored to level of experience of the operator. Dr Reifart suggested that a level C operator is one who has undertaken less than 500 PCIs and should only undertake PCI of simple lesions and simple bifurcations. A level B operator has undertaken 500–1000 PCIs and can therefore attempt more complex procedures such as complex bifurcations, moderate calcified lesions and some cases of CTO. Only a level A operator, i.e. one who has performed more than 1000 PCIs, including 300 CTO, might undertake complex cases such as long and highly calcified lesions and complex CTOs including retrograde. If a level C operator attempts a level A task, he/she is less likely to be successful and may cause harm to the patient.
Other considerations for procedural safety are the use of premedication and the amount of contrast used. The volume of dye used in a PCI procedure should not exceed 4–6 x the glomerular filtration rate (GFR). In terms of procedural time, completion within 60 min in 90 % of cases is expected. It is important to prepare for complications such as pericardial effusion. Finally, stent selection is important; the operator must decide which stent type and size is appropriate for the patient and the lesion. Contemporary DES should be considered for all CTO procedures.
Live Case from Instituto Cardiovascular/ Hospital Clínico San Carlos – Madrid, Spain
Case 1: RCA CTO in multi-vessel disease. Operators: George Sianos, Antonio Fernandez-Ortiz
A case was presented of a 78 year-old man with hypertension, effort angina over the last month and resting chest pain. He had a severe calcified lesion in the proximal left anterior descending artery (LAD) and total occlusion of the right coronary artery (RCA). His SYNTAX score was 30. The LAD was treated fırst and the RCA was deferred for a second procedure performed lıfe durıng the meetıng.
A PCI procedure of the RCA was undertaken, with the aim of implanting the Coracto™ sirolimus-eluting stent wıth bıodegradable polymer. The right femoral access approach was taken using a 7 Fr guidıng catheter for the donor artery and the right radial artery usıng a 6 Fr guıdıng catheter for the occluded artery. The CTO length was 10-15 mm with presence of some calcification. A procedural plan was presented: if one approach failed the next would be tried. An antegrade approach was initially used, with a plan to shift to retrograde if needed. During the procedure, the antegrade wire entered the subintimal space, and the wire could not cross to the distal true lumen, necessitating the retrograde approach to achıeve fınal success. Two Coracto™ sirolimus elutıng stents were successfully implanted wıth a very good final result.
Live case from Instituto Cardiovascular / Hospital Clínico San Carlos - Madrid, Spain
Case 2: LAD CTO in single-vessel disease. Operators: Javier Escaned, Luis Nombela-Franco
This case was a 63 year-old man with a single-vessel CTO. The coronary angiogram showed occlusion of the LAD at a bifurcation of a large fırst diagonal branch.
A PCI procedure of the LAD was undertaken, with the aim of implanting the Cre8 amphilimus polymer free elutıng stent. The procedure started with the use of IVUS to guide the puncture of the proximal cup wıth contemporary CTO guidewires. The procedure was not conceded during dedicated transmission tıme and continued further, but later had to be abandoned for a second attempt in the future.
Dr Yamane concluded the session by emphasising the key messages. Patients with CTO and significant ischemia are at risk of MACE and have a clear indication for PCI. In terms of CTO and multi-vessel disease, timing is important, and much depends on whether complete revascularization can be achieved, the available equipment and expertise of the operator. It is important to be strict in terms of activated clotting time (ACT) monitoring and to be flexible in strategy selectıon; it is frequently necessary to switch strategies durıng the procedure. Safety and long-term outcomes should always be the priority in any procedure. In terms of stent selection, once the vessel is open in a CTO, it is essential to use thin-strut biodegradable polymer or polymer free drug-eluting stents (DES) that exert low-restenosis rates, as restenosis rates are still high in CTO patients.