Mechanical atrioventricular valve replacement during and after the single ventricle palliation

BACKGROUND: Mechanical atrioventricular valve (AVV) replacement in single-ventricle patients carries significant risks with limited outcome data. We evaluated outcomes and identified risk factors for mortality after mechanical AVV replacement during staged Fontan palliation. METHODS: We retrospectively reviewed 22 patients who underwent mechanical AVV replacement from 1997 to 2022 after completing at least stage I palliation. Patients were stratified by early postoperative ventricular function (normal vs impaired) and timing of AVV replacement (primary vs post-AVV repair). The primary outcome was transplant-free survival. RESULTS: Median age at valve replacement was 1.7 years (interquartile range, 0.5-8.0 years). Hypoplastic left heart syndrome was the most common diagnosis (n = 10), and the Norwood procedure was the most frequent stage I palliation (n = 13). AVV replacement was performed before or at Fontan completion in 14 patients and after in 8 patients. A previous AVV repair was performed in 11 patients. Intraoperatively, 8 patients converted to AVV replacement after attempted AVV repair. There were 4 in-hospital deaths (18.2%). Transplant-free survival at 1 year was 55.6%. Postoperative reduced ventricular function (hazard ratio, 4.890; P = .018) and longer cardiopulmonary bypass time (hazard ratio, 1.013; P = .033) were risk factors for death. Patients with preserved ventricular function showed significantly better survival than those with impaired function (mild, moderate, or severe) (100% vs 25.7% at 1 year, P < .001). CONCLUSIONS: Approximately 1 in 10 single-ventricle patients undergoing AVV surgery required mechanical AVV replacement. Outcomes depend on the preserved ventricular function and the results of valve repair before AVV replacement.