Impact of Coronary Sinus Reducer on Angina Symptoms in Patients With Myocardial Ischemia Without Obstructive Coronary Artery Disease

Background Coronary sinus (CS) Reducer implantation shows favorable results in alleviating angina symptoms in patients with obstructive coronary artery disease (CAD) with non‐revascularizable lesions. Whether CS Reducer is effective also in patients without obstructive epicardial CAD remains unsettled. Aims We sought to assess the potential benefits of the CS narrowing in patients without obstructive presenting with refractory angina. Methods Consecutive refractory angina patients, with objective evidence of myocardial ischemia despite optimal medical therapy (OMT), who underwent CS Reducer implantation, were enrolled in an international registry. Study cohort was divided into two groups: patients with non‐obstructive CAD (< 50% narrowing in all epicardial coronary arteries or a negative intracoronary fractional flow reserve test in case of intermediate lesions), and patients with obstructive CAD. The study outcome was the improvement of the Canadian Cardiovascular Society (CCS) angina score at 12‐month follow‐up in both groups of patients. Results Of 285 enrolled patients with successful CS Reducer implantation, 46 patients (16%) had non‐obstructive CAD and 239 patients (84%) had obstructive CAD. Baseline CCS angina score was similar in both groups (2.9 ± 0.5 vs. 2.9 ± 0.6, p = 0.884). At 12‐month follow‐up, the improvement in CCS angina score was similar in both groups (−1.4 ± 0.8 vs. −1.3 ± 0.9 vs. p = 0.67). Both groups had the same CCS angina score at 12‐month follow‐up (1.6 ± 0.8 p = 0.80). Improvement of ≥ 2 CCS classes were 41.9% and 45.1% in patients with non‐obstructive and obstructive CAD, respectively, p = 0.6746. Conclusions In patients with refractory angina and myocardial ischemia, CS Reducer implantation improves angina symptoms in patients with myocardial ischemia with and without obstructive CAD.