Safety and efficacy of coronary sinus narrowing in chronic refractory angina: Insights from the RESOURCE study

Introduction: Refractory angina (RA) is considered the end-stage of coronary artery disease, and often has no interventional treatment options. Coronary sinus Reducer (CSR) is a recent addition to the therapeutic arsenal, but its efficacy has only been evaluated on small populations. The RESOURCE registry provides further insights into this therapy. Methods: The RESOURCE is an observational, retrospective registry that includes 658 patients with RA from 20 centers in Europe, United Kingdom and Israel. Prespecified endpoints were the amelioration of anginal symptoms evaluated with the Canadian Cardiovascular Society (CCS) score, the rates of procedural success and complications, and MACEs as composite of all-cause mortality, acute coronary syndromes, and stroke. Results: At a median follow-up of 502 days (IQR 225–1091) after CSR implantation, 39.7% of patients improved by ≥2 CCS classes (primary endpoint), and 76% by ≥1 class. Procedural success was achieved in 96.7% of attempts, with 3% of procedures aborted mostly for unsuitable coronary sinus anatomy. Any complication occurred in 5.7% of procedures, but never required bailout surgery nor resulted in intra- or periprocedural death or myocardial infarction. One patient developed periprocedural stroke after inadvertent carotid artery puncture. At the last available follow-up, overall mortality and MACE were 10.4% and 14.6% respectively. At one, three and five years, mortality rate at Kaplan-Meier analysis was 4%, 13.7%, and 23.4% respectively. Conclusions: CSR implantation is safe and reduces angina in patients with refractory angina.