Early mitral valve surgery may improve long-term survival in asymptomatic severe mitral regurgitation

1. Among patients with asymptomatic severe primary mitral regurgitation, early mitral valve surgery improved long-term survival compared with watchful waiting.

Evidence Rating Level: 2 (Good)

Study Rundown: Timely surgical intervention for primary mitral regurgitation (MR) is critical to prevent irreversible ventricular dysfunction and other adverse clinical events. The optimal timing of surgical intervention for asymptomatic patients remains uncertain due to the lack of randomized clinical trials (RCTs). Previous observational studies have suggested early mitral valve (MV) surgery to be associated with improved survival and a reduced risk of heart failure, although these studies had several limitations. This cohort study thus examined whether early MV surgery (within 6 months of diagnosis) was associated with improved survival compared with watchful waiting among patients with asymptomatic severe primary MR, using the target trial emulation framework for approximating RCTs. This study included patients with asymptomatic severe primary MR from a multi-center valve registry in South Korea. The primary outcome was all-cause mortality and the secondary outcome was a composite of all-cause mortality or heart failure hospitalization. Among the 802 patients, 344 received early surgery, and 458 underwent watchful waiting. In total, 27 deaths occurred in the early surgery group and 103 in the watchful waiting group during a median follow-up of 7.4 years. The mean survival time at 5 years in the early surgery group was 66 days longer than in the watchful waiting group. The survival benefit increased from 3 to 15 years post-randomization, with the early surgery group showing a 31% lower hazard of all-cause mortality compared with the watchful waiting group. Overall, this study found that early MV surgery in patients with asymptomatic severe primary MR improved long-term survival compared with watchful waiting.

Click to read the study in JAMA Network Open 

Relevant reading: Association Between Early Surgical Intervention vs Watchful Waiting and Outcomes for Mitral Regurgitation Due to Flail Mitral Valve Leaflets

In-Depth [cohort study]: This study included patients with asymptomatic severe primary MR (degenerative, rheumatic, or congenital MR) from a multi-center valve registry in South Korea between 2000 and 2022. The early surgery group included patients who received MV repair or replacement within 6 months of diagnosis, whereas the watchful waiting group included those who did not receive surgery within 6 months of diagnosis, even if they underwent surgery later. The primary outcome was all-cause mortality measured using the difference in restricted mean survival time (RMST). The secondary outcome was a composite of all-cause mortality or heart failure hospitalization, measured using hazard ratios (HRs). A clone-censor-weight approach was used to emulate a target trial. Stabilized inverse probability of censoring weights (IPCWs) were used to account for artificial censoring. Among the 802 patients analyzed (mean [SD] age, 55 [16] years; 476 men [59%]), 344 received early surgery, and 458 received watchful waiting. In total, 27 deaths occurred in the early surgery group and 103 in the watchful waiting group during a median (IQR) follow-up of 7.4 (4.1-11.6) years. The mean survival time at 5 years in the early surgery group was longer than in the watchful waiting group (IPCW-adjusted RMST: 1717 days [95% CI, 1667-1772 days] vs 1651 days [95% CI, 1609-1691 days]; absolute difference, 66 days [95% CI, 19-129 days]). The survival benefit increased from 3 to 15 years post-randomization, with the early surgery group showing a lower hazard of all-cause mortality compared with the watchful waiting group (IPCW-adjusted HR, 0.69; 95% CI, 0.41-0.94).

Overall, this study found that among patients with asymptomatic severe primary MR, early MV surgery improved long-term survival compared with watchful waiting. These findings support early surgical intervention for asymptomatic primary MR. A strength of this study was the use of the clone-censor-weight approach within a target trial emulation framework, which supports causal interpretation of the treatment effect. Some limitations of this study include the use of an observational database that may result in residual confounding, and the absence of longitudinal clinical and echocardiographic changes after time zero from some institutions that may result in residual bias. Future longitudinal studies are needed to confirm these findings and address these limitations.

Citation: Ahn J, Kwak S, Lim J, Kim K, Kim J, Sun BJ, et al. Early Mitral Valve Surgery and Survival in Asymptomatic Severe Primary Mitral Regurgitation. JAMA Netw Open. 2026 Oct 1;9(10):e2637061. doi: 10.1001/jamanetworkopen.2026.37061. PMID: 42832200; PMCID: PMC13639776.

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