Mechanical Mitral Valve Replacement in Patients Under 18 Years of Age.

BackgroundPediatric mechanical mitral valve replacement (mMVR) is a high-risk procedure associated with long-term complications and lifelong anticoagulation. This study aimed to evaluate long-term outcomes of mMVR in patients under 18 years of age and to identify risk factors for survival and reoperation.MethodsWe retrospectively analyzed 118 patients under 18 years of age who underwent mMVR at a single center from 1965 to 2024. Demographics, operative data, and outcomes were reviewed. Survival was assessed using Kaplan-Meier analysis, and competing risk models evaluated reoperation. Cox regression identified risk factors for mortality and redo mMVR.ResultsMedian age and weight at initial mMVR were 6.3 years and 14.0 kg, respectively. Early mortality was 12% (14/118), with 24 late deaths over a median follow-up of 15.6 years. Overall survival at 5, 10, 20, and 30 years was 70.5%, 65.0%, 61.5%, and 61.5%, respectively. Multivariate analysis identified non-bileaflet valve use (HR = 2.46) and surgery year (HR = 1.03) as independent predictors of mortality. Thirty three patients underwent 36 redo mMVR, mainly for structural valve deterioration or patient-prosthesis mismatch, with a median interval of 10.1 years. Age <10 years at initial mMVR was an independent predictor of redo mMVR. Young patients receiving adequately sized prostheses demonstrated excellent long-term freedom from redo mMVR.ConclusionsLong-term survival after pediatric mMVR is satisfactory. Valve type and surgery year significantly impact mortality, while younger age at surgery increases the risk of redo mMVR. These findings underscore the importance of timing and prosthesis selection to improve long-term outcomes in pediatric mMVR patients.