Treatment of microvascular angina with the coronary sinus reducer: a first experience

Abstract The Coronary Sinus Reducer (CSR) is an hourglass-shaped device approved for the treatment of refractory angina. Its percutaneous implantation in the coronary sinus leads to a retrograde increase in venous pressure, which is thought to improve capillary recruitment and perfusion to the ischemic myocardium. No data is however available on the use of the CSR to treat microvascular angina, an increasingly recognized but still poorly understood condition. In this preliminary study, we evaluated the efficacy of the CSR in a small cohort of patients with non-obstructive disease. We screened consecutive patients from the prospective COMPLEX registry that received a CSR for refractory angina between June 2018 and November 2022. Inclusion criteria were the absence of obstructive coronary artery disease (<50% narrowing in all coronary arteries, or a negative intracoronary fractional flow reserve test) and no prior history of revascularization. Endpoints were angina and dyspnea symptoms, evaluated with the Canadian Cardiovascular Society (CCS) and the New York Hearth Association (NYHA) scores respectively, procedural success rate, and major adverse cardiovascular events (MACE), defined as a composite of all-cause mortality, cardiovascular death, acute coronary syndromes (ACS) and heart failure (HF) hospitalizations. We ultimately enrolled 8 patients; 6 (75%) were females and mean age was 67.8±9.9 years. Their baseline characteristics are further depicted in table 1. Microvascular dysfunction was invasively confirmed in 5 (62.5%) patients; mean index of microvascular resistance (IMR) was 32.8±15.7 and mean coronary flow reserve (CFR) was 1.7±0.7. In one patient, reduced global CFR (1.4) was evident on cardiac magnetic resonance examination. At baseline, mean CCS class was 2.9±0.6, NYHA class 2±0.9, and number of antianginal drugs 2.6±1.6. Procedural success was 100%, with only one patient experiencing a procedure-related complication (sternocleidomastoid muscle hematoma requiring no intervention). At a median follow-up of 647.5 days (IQR 132-732), mean CCS class was 1.5±0.8, NYHA class 1.9±0.9 and number of antianginal drugs 1.9±1.1. All patients improved by ≥1 CCS class and 3 (37.5%) by ≥2 CCS classes. No MACE was observed. To the best of our knowledge, we present the first report of CSR implantation for the treatment of microvascular angina. Our positive results are particularly promising given the paucity of treatment options currently available for the condition, but larger studies are needed to confirm these findings.table 1figure 1