Predictors of cardiac death in patients with coronary chronic total occlusion not revascularised by PCI

147

By Cosmo Godino

 

Coronary chronic total occlusions (CTOs) remain a technical challenge and an unresolved clinical dilemma, even after numerous successes and rapid progression in the field of interventional cardiology. As shown by registry-based studies, the rationale behind CTO revascularisation is that of it provides improved survival and quality of life. However, until now there is no evidence regarding which category of patients benefit most from CTO revascularisation and conversely, which subgroups of not revascularised patients are at highest risk of future cardiac events. Moreover, the lack of a true randomised controlled trial with a medically treated control group raises the question of whether the survival benefit demonstrated with successful percutaneous coronary intervention (PCI) is, in fact, related to beneficial effects of opening a chronically occluded vessel versus potential harm conferred to those with CTO-PCI failed.

It has been hypothesised that failure of CTO-PCI is simply a marker for increasing baseline patient and lesion complexity, and therefore the poorer outcomes seen in this group are related to the baseline burden of disease rather than any beneficial effect of CTO recanalisation. Therefore, a major limitation of previous observational studies was the limited information with regard to potential baseline differences between successful versus unsuccessful cohorts. In order to avoid this limitation, we choose to perform a separate Cox proportional hazards analysis controlling the possible confounding influence of several independent variables for cardiac death in both groups of patients revascularised or not revascularised. From a central database of two hospitals in Milan (San Raffaele Hospital and GVM-EMO Centro Cuore Columbus) a total of 9,789 consecutive patients referred to us over 10 years (January 1998 to March 2008) for coronary angiography, we identified 1,345 patients (13%) who matched the inclusion and exclusion criteria for CTO. Of these, 847 patients (63%) were successfully recanalised (revascularised CTO patients) and 498 patients (37%) were not revascularised (not revascularised CTO patients), either due to CTO-PCI failure (68%) or CTO-PCI having not being attempted (32%).

Our results confirm that CTO revascularisation remains independently associated, even after a multivariate adjustment, with reduced cardiac death (2.5% vs. 8.5%, p<0.0001), as noted before, and also in terms of sudden cardiac death (0.5% vs. 2.7%, p=0.001), which had never been reported before.

However, as in many areas of medicine, we believe that one size does not fit all and in each case we should balance the real clinical improvement after CTO-PCI recanalisation against the risk that such complex procedures can provide (such as coronary perforation and risk of radiation exposure). Therefore, it would be more appropriate to identify those subgroups who would benefit the most from CTO-PCI recanalisation prior to an attempt.Infact, we observed that amongst not revascularised CTO patients, only those presenting certain risk factors are at increased risk of future cardiac death. In the not revascularised group, patients with chronic renal failure have the highest risk (HR 6.0), followed by those with low left ventricle ejection fraction (HR 5.7) and then patients with insulin-dependent diabetes mellitus (HR 4.6). Of note, patients not revascularised without the above risk factors, do not have much different cardiac mortality rate than those Revascularised (as for patients stratified for low left ventricle ejection fraction). Therefore, our results suggest that for some subgroups of patients achieving recanalisation of CTO may be more needed than for others. In these cases, we believe that CTO recanalisation should be recommended with additional consideration for second and third percutaneous attempts using also retrograde approach and/or alternative techniques (STAR, mini-STAR or other subintimal approach). In addition, when CTO recanalization is not achieved percutaneously (multiple failure attempts, too complex lesion) it may not be sufficient to treat these higher risk patients (with chronic renal failure, low-LVEF or insulin-dependent diabetes mellitus) with medical therapy alone, but surgical revascularisation should be considered even if there is an increased risk of peri-procedural complications.

In conclusion, I believe that not all our efforts should be directed toward technical and procedural aspects to achieve final CTO-PCI recanalisation. More attention should be paid on patients selection and perhaps clinical and surgical considerations should come up front during a global risk assessment by an “heart team” able to evaluate at the beginning which kind of approach would be the best for each patient affected by CTO.

Cosmo Godino is an interventional cardiologist, Cardio-Thoracic-Vascular Department, San Raffaele Hospital, Milan, Italy.