Risk factors and long-term outcomes of complete atrioventricular septal defect repair in children.

BACKGROUND: The prognostic determinants following primary biventricular repair for complete atrioventricular septal defect are complex. We describe contemporary surgical outcomes from a large cohort. METHODS: We retrospectively enrolled 342 patients who underwent primary biventricular complete atrioventricular septal defect repair between January 2010 and April 2025. Univariable and multivariable Cox regression were used to determine predictors. Reoperation and mortality were described using cumulative incidence functions estimated by Fine-Gray competing-risk models. RESULTS: Median follow-up was 8.3 years. Reoperation occurred in 36 (10.5%) patients and 22 (6.4%) died. Multivariable analysis showed that early post-operative left atrioventricular valve regurgitation > moderate (hazard ratio = 6.03, P < 0.001) and age < 3 months (hazard ratio = 3.80, P = 0.018) were independent risk factors for reoperation. Complete cleft closure (hazard ratio = 0.38, P = 0.032) was protective. Reoperation was strongly associated with mortality (hazard ratio = 3.01, P = 0.023). Competing-risk analysis confirmed trisomy 21 was associated with lower reoperation risk (Fine-Gray, P = 0.015). CONCLUSIONS: Patients with complete atrioventricular septal defect have favourable long-term outcomes after primary biventricular repair. Younger age, early post-operative left atrioventricular valve regurgitation > moderate, incomplete cleft closure, and without trisomy 21 are risk factors for reoperation. Reoperation is a significant risk factor for mortality.