Coronary sinus reduction therapy for refractory angina: Current evidence and future directions.

Refractory angina is a chronic, debilitating condition characterized by persistent anginal symptoms despite optimal medical therapy and when further revascularization is not feasible. This condition is a major global cardiovascular healthcare challenge. The coronary sinus reducer represents an emerging therapeutic option intended to relieve symptoms by increasing coronary venous pressure and redistributing myocardial blood flow to ischemic subendocardial regions. Growing evidence has demonstrated improvements in angina class and quality of life, although results vary across studies and benefit magnitude is modest in blinded studies. This device appears to be safe and effective in reducing angina burden and improving quality of life in appropriately selected patients. Mechanistic understanding continues to evolve, and large ongoing randomized trials and meta-analyses aim to refine the indication, patient selection (including patients with microvascular angina), and long-term outcomes. Health-technology appraisals recognize potential clinical utility but call for more robust long-term data. This review provides an up-to-date description of the device, physiological rationale, clinical evidence, procedural technique, complications, and future directions. It also highlights knowledge gaps and discusses areas of on-going research.