Coronary Sinus Reducer Demonstrates Long-Term Efficacy in Refractory Angina: Insights from REDUCER-I

Refractory angina, characterized by persistent symptoms despite optimal medical therapy and coronary revascularization, remains an unmet clinical challenge, adversely affecting patient quality of life and healthcare expenses. The coronary sinus reducer (CSR) device, designed to enhance subendocardial perfusion by increasing coronary sinus pressure, has shown promise in prior controlled trials, including the sham-controlled randomized trial COSIRA, where it improved Canadian Cardiovascular Society (CCS) angina class. The observational REDUCER-I study aims to evaluate the real-world safety and effectiveness of this device in a broader population.

The study enrolled 400 patients across 25 European centers from 2016 and 2023 (mean age of 68.8 +/- 9.7 years, 78% male). Of these, 371 actually received the device. Participants presented with severe angina (72% CCS class III/IV) and were ineligible for further revascularization. About 20% had nonobstructive coronary disease. Patients underwent CSR implantation, and outcomes were assessed at six months and through three years. The primary effectiveness endpoint was improvement in CCS class at six months, while safety endpoints included rates of major adverse cardiac events (MACE) and device- or procedure-related serious adverse events (SAEs) within 30 days.

At six months, 69.8% of patients experienced at least a one-class improvement in CCS angina severity, and 24.1% improved by two or more classes. The mean CCS class improved from 2.8 to 1.8 (p<0.0001). Quality of life, as measured by the Seattle Angina Questionnaire, significantly improved across all domains (p<0.0001). Functional capacity also increased, with a mean six-minute walk test (6MWT) distance improving by 34.1 meters (p<0.0001). Interim three-year results showed sustained benefits in angina class and quality of life.

The CSR demonstrated a favorable safety profile. The 30-day MACE rate was 1.6%, with no deaths and a low rate of device-related complications (1.1%). These results align with prior controlled studies, reinforcing the device’s role in reducing angina severity and enhancing patient functionality in a real-world setting.

The findings highlight the CSR’s potential as a durable and effective option for patients with refractory angina who lack revascularization options. The inclusion of patients with both obstructive and nonobstructive coronary artery disease (CAD) broadens its applicability. Future studies, including COSIRA-II and REMEDY-PILOT, aim to further clarify patient selection criteria and explore its efficacy in specific subsets such as those with microvascular angina or ischemia and nonobstructive coronary arteries (INOCA). These efforts will address remaining gaps in understanding the CSR’s mechanistic benefits and long-term outcomes, offering new hope for a population with limited therapeutic options.

References

Verheye, S, van de Hoef, T, de Silva, R. et al. Coronary Sinus Narrowing for Treating Refractory Angina: REDUCER-I Multicenter “Real-World” Observational Study Primary Endpoint Analysis. J Am Coll Cardiol Intv. 2024 Dec, 17 (24) 2908–2918. https://doi.org/10.1016/j.jcin.2024.08.047