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Safety, Efficacy, and Effectiveness of Coronary Sinus Reducer Implantation in Refractory Angina: A Meta-Analysis
Utkarsh Ojha1, Muhammad Mohsin2, Krzysztof Macierzanka2
1East Kent Hospitals University NHS Foundation Trust, Queen Elizabeth The Queen Mother Hospital, Margate, United Kingdom.
Insights
Coronary sinus reducers (CSR) show antianginal benefits in refractory angina (RA), but placebo-controlled trials reveal lower efficacy than previously reported. Larger trials are needed to confirm clinical utility.
Area of Science:
- Cardiology
- Interventional Cardiology
- Clinical Trials
Background:
- Previous meta-analyses on coronary sinus reducers (CSR) for refractory angina (RA) relied on single-arm studies, conflating true efficacy with placebo and confounding effects.
- Evaluating the true physical effect of CSR necessitates comparative data from randomized controlled trials (RCTs), ideally double-blind and placebo-controlled.
Purpose of the Study:
- To assess the safety and efficacy of CSR in patients with RA.
- To compare the efficacy of CSR with observed effectiveness using data from RCTs and single-arm studies.
Main Methods:
- A systematic review and meta-analysis of RCTs and single-arm studies on CSR for RA.
- Pooled data using random-effects models for single-arm, RCT intervention-arm, and RCT placebo-controlled estimates.
- Therapeutic outcomes included Canadian Cardiovascular Society classification, Seattle Angina Questionnaire scores, and treadmill exercise time; safety outcomes included procedural success and adverse events.
Main Results:
- Analysis included 3 double-blind, placebo-controlled RCTs (n=180) and 13 single-arm studies (n=668). Procedural success rate was 98.3%.
- Placebo-controlled trials showed significant improvements in Canadian Cardiovascular Society classification (≥1-class: 26%; ≥2-class: 17%) and exercise time (+49.62 seconds).
- Seattle Angina Questionnaire data lacked sufficient placebo-controlled evidence of benefit; placebo-controlled efficacy was approximately one-third of single-arm study findings.
Conclusions:
- Coronary sinus reducer implantation is safe and feasible, showing promising antianginal effects in RA.
- Current efficacy findings are uncertain due to susceptibility of effectiveness data to nonphysical influences.
- Larger, placebo-controlled trials are warranted to definitively establish the clinical utility of CSR.
Background:
Previous coronary sinus reducer (CSR) meta-analyses in refractory angina (RA) focused on single-arm studies, capturing observed effectiveness-comprising the physical effect of CSR, contextual effects (eg, placebo), and non-treatment-related phenomena (eg, confounding). Efficacy evaluation requires comparative estimates from randomized controlled trials (RCTs), ideally double blind and placebo controlled, to isolate the physical effect.
Objectives:
The aims of this study were to evaluate the safety and efficacy of CSR in RA and to compare its efficacy with observed effectiveness.
Methods:
The study was preregistered with the International Prospective Register of Systematic Reviews (CRD42023399099). Electronic databases were searched until April 2024. Random-effects models separately pooled single-arm, isolated RCT intervention-arm, and RCT placebo-controlled estimates. Therapeutic outcomes included improvements in Canadian Cardiovascular Society classification, Seattle Angina Questionnaire scores, and treadmill exercise time. Safety outcomes, summarized descriptively, comprised procedural success and adverse events.
Results:
Three double-blind, placebo-controlled RCTs (n = 180) and 13 single-arm studies (n = 668) were analyzed. The overall unweighted procedural success rate was 98.3% (95% CI: 97.0%-99.1%). Single-arm studies and RCT intervention arms demonstrated statistically significant improvements across therapeutic outcomes. For Canadian Cardiovascular Society classification, placebo-controlled rates were 26% (95% CI: 11%-38%; P < 0.001) for ≥1-class improvement and 17% (95% CI: 2%-37%; P = 0.02) for ≥2-class improvement, representing approximately one-third of single-arm improvement rates. Seattle Angina Questionnaire domain analyses demonstrated insufficient placebo-controlled evidence of benefit. Placebo-controlled exercise time change was 49.62 seconds (95% CI: 1.84-97.40 seconds; P = 0.04).
Conclusions:
CSR implantation is safe and feasible and demonstrates promising antianginal efficacy in patients with RA. However, uncertainty in current efficacy findings and susceptibility of effectiveness data to nonphysical influences preclude definitive conclusions about clinical utility, warranting larger placebo-controlled trials.
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