Coronary sinus reducer (CSR) implants are safe and feasible with promising effects for refractory angina (RA) patients, and need bigger randomized trials to confirm the potential benefit, according to a new meta-analysis. The findings were published online ahead of the August 11 issue of JACC: Cardiovascular Interventions, led by Utkarsh Ojha, MBBS, BSc, from the Queen Elizabeth The Queen Mother Hospital, and Muhammad Mohsin, BSC, from Imperial College London. Characterized by persistent chest discomfort despite maximal antianginal treatment, RA affects a growing subset of chronic coronary artery disease patients, and has limited therapeutic options, the researchers noted. Percutaneous implantation of CSR, an hourglass-shaped stainless steel mesh, has emerged as a promising treatment for RA symptomatic relief, however, its use is largely supported by unblinded single-arm studies which often neglect comparative randomized control trial (RCT estimated, the researchers noted. The current study therefore set out to assess the safety and efficacy of CSR in RA and compare its efficacy with observed effectiveness in recipients across 3 parallel-arm, double-blind, sham-controlled RCTs (n = 180) and 13 unblinded single-arm studies (n = 668). The included cohorts were predominantly male, typically with obstructive coronary artery disease, average age >60 years, with high rates of prior revascularization and comorbidities. The researchers concluded that the implant is safe, with an overall unweighted procedural success rate of 98.3% (95% confidence interval [CI]: 97% - 99.1%) overall. No periprocedural mortality or strokes were reported, though there were a total four acute coronary syndrome events (single-arm studies, n = 1; RCT intervention arms, n = 2; RCT control arms, n = 1), all occurring days post-procedure. The most common complication was migration of the device in 1.5% (95% CI: 0.8% - 2.7%). The single-arm studies and RCT intervention arms also pointed towards improvements across therapeutic outcomes, including placebo-controlled rates of 26% (95% CI: 11%-38%; P < 0.001) for Canadian Cardiovascular Society classification improvement ≥1 class, and 17% (95% CI: 2%-37%; P = 0.02) for ≥2-class improvement. Comparative RCT analyses demonstrated overall risks (ORs) of 2.98 (95% CI: 1.53-5.78) and 2.79 (95% CI: 1.21-6.45) for ≥1- and ≥2-class improvements, respectively. However, for another score, the Seattle Angina Questionnaire [SAQ], "domain analyses demonstrated insufficient placebo-controlled evidence of benefit," the researchers wrote. Meanwhile, placebo-controlled exercise time change was 49.62 seconds (95% CI: 1.84-97.40 seconds; P = 0.04). The researchers concluded, "This meta-analysis shows that although single-arm studies support substantial improvements in symptoms and quality of life following CSR implantation, doubleblind placebo-controlled trials reveal smaller yet tangible benefits directly attributable to CSR implantation after accounting for factors such as the placebo effect and confounding. "This highlights a notable gap between the observed effectiveness and actual efficacy of CSR in RA." They called for larger placebo-controlled trials to confirm clinically meaningful efficacy before broader adoption. In an accompanying editorial, Michael Vavuranakis, MD, PhD, and Deepak L. Bhatt, MD, MPH, from , Icahn School of Medicine at Mount Sinai, New York, surmised that there "may be a role for the CSR in future clinical practice, particularly for patients with refractory angina, as it might provide improvements in symptomatology and quality of life". However, they stressed that several key considerations must still be addressed, including establishing clear criteria for patient selection and procedural success, the inclusion of objective measures in research such as changes in coronary sinus pressure gradient pre- and post-implantation, and the definition of optimal antithrombotic therapy. In any case, all editorialists and researchers agreed that more data is needed to fully prove efficacy. "Health care systems should resist the pressure to approve and reimburse devices such as the CSR before robust data supporting utilization," the editorialists stressed. Sources: Ojha U, Mohsin M, Macierzanka K, et al. Safety, Efficacy, and Effectiveness of Coronary Sinus Reducer Implantation in Refractory Angina: A Meta-Analysis. JACC: Cardiovasc Interv; 18: 1864-1877. Vavuranakis M, Bhatt DL. Relieving the Pressure: Evaluating the Coronary Sinus Reducer for Refractory Angina. JACC: Cardiovasc Interv; 18: 1878-1880. Image Credit: REDPIXEL – stock.adobe.com