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Dr. Chugh’s comments regarding our chronic total occlusion (CTO) experience are well stated and germane to our findings. Our intent for this project was to investigate the association between long-term survival and successful recannulization of a CTO. In order to demonstrate this association, a matched cohort was developed using a propensity-scoring model. Thus, the comparison groups were remarkably similar with respect to baseline covariates that are known predictors of long-term survival. In fact, the survival curves for the matched cohort and the CTO group were markedly similar. Only those patients with a successful recannulization of a CTO demonstrated a survival benefit. This link persisted following multivariate adjustment and was identified in the failed percutaneous coronary intervention (PCI) cohort in whom successful surgical recannulization of the CTO was performed.
In our opinion, this body of work clearly identifies a group of patients in whom successful PCI is associated with improved long-term survival. There is no question that further work needs to be performed on the mechanism of survival. Two leading theories are certainly collateral flow and viability. Other plausible explanations that are worthy of future investigation include the effect of successful recannulization upon the incidence of sudden cardiac death, left ventricular remodeling, and identification of certain clinical patient subsets that are associated with an improved survival following CTO and recannulization. For example, patients with a history of diabetes mellitus have been demonstrated to have a decreased incidence of collateral vessel formation despite abnormal coronary atherosclerosis. However, patients with a history of diabetes mellitus derived substantial benefit from a successful recannulization of a chronic total occlusion in our study (data not shown). To further our understanding of this cohort, we have identified 558 patients from our nuclear database with a peri-procedural radionucleotide perfusion study. We are hopeful that this additional information will result in an enhanced understanding of the survival benefit of successful recanalization of a CTO.
Finally, Dr. Chugh’s comments are insightful and, it is hoped, will prompt future investigation into the mechanism of survival benefit associated with a successful recannulization of a CTO.
- American College of Cardiology Foundation