Outcomes of Mechanical Mitral Valve Replacement in Children.

Background: Mitral valve anomalies in children are rare but frequently severe, recalcitrant, and not often amenable to primary repair, necessitating mechanical mitral valve replacement (M-MVR). This study examined outcomes of a cohort undergoing a first M-MVR at age younger than 21 years.

Methods: We queried the Pediatric Cardiac Care Consortium, a multi-institutional United States-based cardiac intervention registry, for patients undergoing first M-MVR for 2-ventricle congenital heart disease. Survival and transplant status through 2014 were obtained from Pediatric Cardiac Care Consortium and linkage with the National Death Index and the Organ Procurement and Transplantation Network.

Results: We identified 441 patients (median age, 4.3 years; interquartile range, 1.3 to 10.1 years) meeting study criteria. The commonest disease necessitating M-MVR was atrioventricular canal (44.3%). Early mortality (death <90 days after M-MVR) was 11.1%; there was increased risk of early death if age at M-MVR was younger than 2 years (odds ratio, 7.8; 95% confidence interval [CI], 1.1 to 56.6) and with concurrent other mechanical valve placement (odds ratio, 8.5; 95% CI, 2.0 to 35.6). In those surviving more than 90 days after M-MVR, transplant-free survival was 76% at 20 years of follow-up (median follow-up, 16.6 years; interquartile range, 11.9 to 21.3 years). Adjusted analysis in those who survived more than 90 days showed elevated risk of death/transplant for boys (hazard ratio, 1.5; 95% CI, 1.0 to 2.3), age at M-MVR younger than 2 years (10-year survival: hazard ratio, 4.3; 95% CI, 1.2 to 15.1), and nonbileaflet prosthesis placement (hazard ratio, 2.4; 95% CI, 1.3 to 4.3).

Conclusions: M-MVR is a viable strategy in children with unrepairable mitral valve disease. Age younger than 2 years at the first M-MVR is associated with significant early risk of death and poorer long-term survival.