Long-term Results after Mitral Valve Replacement with Mechanical Prostheses in Children under 3 Years of Age.

Background: This study investigated the long-term results of mitral valve replacement (MVR) using mechanical prostheses in children under 3 years of age. Methods: We retrospectively reviewed 24 patients who underwent MVR with mechanical prostheses before the age of 3 years between 1996 and 2019. Underlying diagnoses included isolated congenital mitral regurgitation (n=4), congenital mitral stenosis (n=4), and various congenital heart defects (n=16). The median follow-up duration was 9.8 years (interquartile range [IQR], 7.3-13.2 years). Results: The median age and weight at MVR were 16.6 months (IQR, 5.3-24.7 months) and 7.6 kg (IRQ, 4.9-9.5 kg), respectively. The median prosthesis size was 19 mm (range, 16-29 mm). Supra-annular implantation was performed in 12 patients (50%), who were significantly younger and smaller at the time of surgery and received smaller prostheses than those receiving annular implants. Early mortality occurred in 2 patients (8.3%), and 2 late deaths were recorded. The overall survival rate was 83.3% at 15 years. Redo MVR was performed in 9 patients during follow-up. The median increase in valve size was 4 mm. The interval from initial to redo MVR was positively correlated with the increase in valve size (Spearman ρ=0.64, p=0.07). Freedom from redo MVR was 86.3% at 5 years and 75.8% at 10 years. Conclusion: MVR with mechanical prostheses in children under 3 years of age can yield acceptable long-term survival, although redo MVR is often required. Mechanical MVR remains a viable salvage option in small children when valve repair is not feasible.