Long-Term Outcomes Following Surgical Management of Congenital Mitral Valve Dysplasia

To evaluate long-term survival and durability after CMVD surgery, and identify factors associated with mortality and mitral valve replacement (MVR).

All patients undergoing surgery for severe forms of CMVD (hammock, parachute, and related phenotypes) at our center between 1975 and 2024 were retrospectively reviewed. Survival was estimated using Kaplan-Meier methods. Time to MVR was analyzed using cumulative incidence accounting for competing risks.

A total of 102 patients (median age, 10 months; [interquartile range (IQR): 6-30]) underwent 187 procedures, with a median follow-up of 11.5 years [IQR: 9.11-15.5]. Overall survival at 10 and 20 years were 86.8% [95%CI: 78.3%-92.1%] and 78.2% [95%CI: 64.7%-87.1%], respectively. Shone's complex was the only factor associated with reduced survival (p=0.018). Age <1 year, Shone's complex, mixed mitral disease, and hammock valve or parachute valve were associated with higher rates of MVR (p<0.05). Among patients undergoing primary repair (n=85), residual mitral regurgitation (MR) strongly impacted repair durability, with a 10-year cumulative incidence of MVR of 0% with none/trivial residual MR, 22.6% [95% CI: 11.1%-46.0%] with mild residual MR, and 52.1% [95% CI: 38.9%-69.8%] with moderate/severe residual MR (p=0.001) Long-term survival did not differ significantly between initial repair and replacement strategies.

Overall long-term outcomes after MV surgery for CMVD are favorable, although diminished by the higher-risk profile of patients with Shone's complex. MVR remains frequent, particularly in infants and complex anatomies, and when residual lesions persist after repair. These findings support the need for improved reconstructive techniques and innovative replacement options in selected patients.