Background: The risk factors for reoperation and mortality after partial and intermediate atrioventricular canal defect repair are unclear. This study assessed the mid-term outcomes and risk factors for reoperation and mortality after partial and intermediate atrioventricular canal defect surgery.

Methods: Ninety-seven patients who underwent primary repair of intermediate (n = 45) or partial (n = 52) atrioventricular canal defect between 2005 and 2019 were included in this single-centre study.

Results: The median age was 5 years (2.7-8.9 years). The median follow-up time was 32 months (1.6-90.8 months). The estimated freedom from reoperation at 1, 5, and 10 years was 97%, 91%, and 73%, respectively.In multivariable analyses, post-operative left atrioventricular valve regurgitation of grade II or higher (odds ratio [OR]: 5.3, 95% confidence interval [CI]: 1.8-15.5, p = 0.01) and post-operative residual intracardiac shunt (OR: 11.6, 95% CI: 1.6-85.8, p = 0.02) were risk factors for reoperation.In multivariable analyses, perioperative reoperation (OR: 93.4, 95% CI: 3.9-218.7, p = 0.01) and the need for right atrioventricular valve repair (OR: 11.2, 95% CI: 1.0 - 123.3, p = 0.04) were risk factors for mortality. Mortality was higher in patients under 2.6 years of age.

Conclusions: For patients undergoing repair of partial or intermediate atrioventricular canal defect, those with post-operative left atrioventricular valve regurgitation of grade II or higher and post-operative residual intracardiac shunt have an increased reoperation risk. Higher mortality can be expected after a perioperative reoperation, and in patients requiring right atrioventricular valve repair during the index procedure.