Variation exists in the timing of surgery for balanced complete atrioventricular septal defect repair. We sought to explore associations between timing of repair and resource utilisation and clinical outcomes in the first year of life.

In this retrospective single-centre cohort study, we included patients who underwent complete atrioventricular septal defect repair between 2005 and 2019. Patients with left or right ventricular outflow tract obstruction and major non-cardiac comorbidities (except trisomy 21) were excluded. The primary outcome was days alive and out of the hospital in the first year of life.

Included were 79 infants, divided into tertiles based on age at surgery (1st = 46 to 137 days, 2nd = 140 – 176 days, 3rd = 178 – 316 days). There were no significant differences among age tertiles for days alive and out of the hospital in the first year of life by univariable analysis (tertile 1, median 351 days; tertile 2, 348 days; tertile 3, 354 days; p = 0.22). No patients died. Fewer post-operative ICU days were used in the oldest tertile relative to the youngest, but days of mechanical ventilation and hospitalisation were similar. Clinical outcomes after repair and resource utilisation in the first year of life were similar for unplanned cardiac reinterventions, outpatient cardiology clinic visits, and weight-for-age z-score at 1 year.

Age at complete atrioventricular septal defect repair is not associated with important differences in clinical outcomes or resource utilisation in the first year of life.