National In-Hospital Outcomes of Mechanical Mitral Valve Replacement in the Pediatric Population.

Background: National data about the outcomes of children undergoing mechanical mitral valve replacement (m-MVR) are scarce. Methods: A retrospective review of hospitalizations from the Kids' Inpatient Database was performed for patients ≤18 years of age in the United States. A total of 500 patients underwent m-MVR in 2009, 2012, 2016, and 2019. Patients with single ventricle physiology were excluded (n  =  13). These patients were categorized into three groups according to age: neonates (<1 month, n  =  20), infants (1-12 months, n  =  76 patients), and children (1-18 years, n  =  404). Outcomes were compared between the three groups. Results: The proportion of m-MVR involving children undergoing MV procedures (repair and replacement) has increased from 17.3% in 2009 to 30.8% in 2019 (Ptrend < .01). History of cardiac surgery was present in 256 patients (51.2%). Concomitant procedures were performed in 119 patients (23.8%). Intra- or postoperative extracorporeal membrane oxygenation was required in 19 patients (3.8%). The overall in-hospital mortality was 4.8% and was significantly higher in neonates and infants compared with older children (10% vs 11.8% vs 3.2%, P  = .003). The length of hospital stay was longer in the neonatal group (median, 57 days, interquartile range, [24.8-90] vs 29.5 days [15.5-61] vs 10 days [7-18], P  < .01). Nonhome discharges were more common in neonates and infants (40% vs 36.8% vs 13.1%, P  < .01). Conclusion: Mechanical mitral valve replacement is increasingly performed over time with acceptable in-hospital morbidity and mortality, especially in older children and adolescents. Neonates and infants are associated with worse hospital survival, prolonged hospitalization, and significant rates of nonhome discharges.