Efficacy and safety of coronary sinus reducer for refractory angina: a systematic review and meta-analysis of randomized controlled trials

Refractory angina affects patients' quality of life around the world. Coronary sinus reducer (CSR) is a new therapeutic approach that has been investigated in recent years. We aimed to investigate the efficacy and safety of CSR for refractory angina. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) from PubMed, Web of Science, Scopus, Embase, and CENTRAL searches until May 2024. Dichotomous data were pooled using risk ratio (RR), and continuous data were pooled using mean difference (MD), both with a 95% confidence interval (CI), using (R version 4.3). With the inclusion of three RCTs, our cohort comprised a total of 180 patients. Compared with the control group, after 6 months, CSR was significantly associated with a decreased mean change of Canadian Cardiovascular Society (CCS) class [MD: -0.54 with 95% CI (-0.80 to -0.27), P < 0.01], a decreased number of patients in the CCS class III/IV [RR: 0.56 with 95% CI (0.38-0.84), P < 0.01], and increased exercise time [MD: 50.46 with 95% CI (9.47-91.45), P = 0.02]. However, there was no significant difference between CSR and the control group in double products, all Seattle Angina Questionnaire domains, and safety outcomes. CSR has been shown to reduce angina severity by lowering CCS class scores and increasing exercise time. Large-scale RCTs are needed to confirm its effectiveness in patients with refractory angina.