Early Mitral Valve Surgery and Survival in Asymptomatic Severe Primary Mitral Regurgitation.

Abstract

Importance: The optimal timing of mitral valve (MV) surgery in patients with asymptomatic severe primary mitral regurgitation (MR) remains uncertain because randomized clinical trials are lacking.

Objective: To evaluate the association of early MV surgery with long-term survival in patients with asymptomatic severe primary MR using a target trial emulation framework.

Design, setting, and participants: This cohort study used a clinical valve registry from 3 tertiary hospitals in South Korea between 2000 and 2022. Patients with asymptomatic severe primary MR were analyzed using a clone-censor-weight approach to emulate a target trial. A 6-month grace period after diagnosis was used to define treatment strategies. This analysis was conducted from September 2024 to January 2025.

Exposure: Early MV surgery (within 6 months of diagnosis) vs watchful waiting.

Main outcomes and measures: The primary outcome was all-cause mortality and the secondary outcome, a composite of all-cause mortality or heart failure hospitalization. Inverse probability of censoring-weighted estimates of the per-protocol effect size included restricted mean survival time (RMST) differences as the primary measure and hazard ratios (HRs) as secondary measures.

Results: Among 802 patients (mean [SD] age, 55 [16] years; 476 men [59%]), 344 underwent early surgery, and 458 received watchful waiting. During a median (IQR) follow-up of 7.4 (4.1-11.6) years, 27 deaths occurred in the early surgery group and 103 in the watchful waiting group. At 5 years, early surgery was associated with an RMST gain of 66 days (95% CI, 19-129 days). The survival benefit persisted up to 15 years. Early surgery was also associated with a lower risk of all-cause mortality compared with watchful waiting (HR, 0.69; 95% CI, 0.41-0.94; P = .02). Similar associations were observed in patients without left ventricular decompensation (HR, 0.61; 95% CI, 0.31-0.96; P = .04) and in those with degenerative MR (HR, 0.66; 95% CI, 0.36-0.98; P = .04).

Conclusions and relevance: In this multicenter cohort study with a target trial framework, early surgery was associated with improved long-term survival among patients with asymptomatic severe primary MR. These findings support consideration of earlier surgical intervention in contemporary clinical practice.