Effectiveness of Coronary Sinus Reducer for Treatment of Refractory Angina: A Meta-analysis

Background: Refractory angina is a debilitating condition that affects the quality of life of patients worldwide, who after exhausting standard available therapies are regarded as “no option” patients. Recently, CS (coronary sinus) reducer (Neovasc Reducer) implantation became available and is gaining popularity in the treatment of refractory angina. The effectiveness of this therapy was demonstrated in 1 randomised sham-control trial and numerous uncontrolled prospective studies entailing several hundred patients altogether. We performed a meta-analysis to incorporate the data and elucidate its efficacy and safety. Methods: A meta-analysis of prospective studies assessing the effects of CS narrowing published in English to June 2021 was performed. The primary outcome was the proportion of patients improving ≥ 1 class in the Canadian Cardiovascular Society (CCS) angina score. Other end points included proportion of patients improving ≥ 2 CCS classes, procedural success, periprocedural complications, changes in Seattle Angina Questionnaire (SAQ) scores, and 6-minute walk test (6MWT). Results: Data from 9 studies including 846 patients were included. An improvement of ≥ 1 CCS class occurred in 76% (95% confidence interval [CI] 73%-80%) of patients. Improvement of ≥ 2 CCS classes was observed in 40% of patients (95% CI 35%-46%). Procedure success was 98%, with no major and 3% nonmajor periprocedural complications. Post procedural SAQ scores and 6MWT distance were significantly improved. Conclusions: In patients suffering from angina refractory to medical and interventional therapies, Reducer implantation improves symptoms and quality of life with a low complication rate. These results are consistent in 1 randomised trial and multiple prospective uncontrolled studies.