Left Ventricular Size Predicts Clinical Benefit After Percutaneous Mitral Valve Repair for Secondary Mitral Regurgitation: A Systematic Review and Meta-Regression Analysis

Background: The benefit of percutaneous mitral valve repair (PMVR) in patients with secondary MR is still debated. We aimed to compare the outcome of PMVR with optimal medical therapy (OMT) versus OMT alone in patients with secondary mitral regurgitation (MR) and to assess the role of potential effect modifiers. Methods: We performed a systematic review and meta-analysis of 2 randomized clinical trials (RCT) and 7 non-randomized observational studies (nROS). Hazard ratios (HR) and 95% confidence intervals (CI) were pooled through inverse variance random-effects model to compute the summary effect size for all-cause death, cardiovascular death and cardiac-related hospitalization. Subgroup and meta-regression analysis were also performed. Results: An overall population of 3118 individuals (67% men; mean age, 73 years) was included: 1775 PMVR+OMT and 1343 OMT patients, with mean follow-up of 24 ± 15 months. PMVR+OMT was associated with a lower risk of all-cause death (HR: 0.77; 95% CI: 0.68–0.87), cardiovascular death (HR: 0.55; 95% CI: 0.34–0.89) and cardiac-related hospitalization (HR:0.77; 95% CI: 0.64–0.92). Meta-regression analysis showed that larger left ventricular end-diastolic volume index (LVEDVI) portends higher risk of all-cause death, cardiovascular death and cardiac-related hospitalization after PMVR (p < 0.001 for all). Conclusions: This study-level meta-analysis shows that PMVR+OMT is associated with reduced all-cause death, cardiovascular death and cardiac-related hospitalization when compared with OMT alone in secondary MR. LVEDVI is a predictive marker of efficacy, as patients with smaller LVEDVI have been shown to derive the largest benefit from PMVR.