Controversial data exist about the impact of Down syndrome on outcomes after surgical repair of atrioventricular septal defect.

(A) assess trends and outcomes of atrioventricular septal defect with and without Down syndrome and (B) determine risk factors associated with adverse outcomes after atrioventricular septal defect repair.

We queried The National Inpatient Sample using International Classification of Disease codes for patients with atrioventricular septal defect < 1 year of age from 2000 to 2018. Patients’ characteristics, co-morbidities, mortality, and healthcare utilisation were evaluated by comparing those with versus without Down syndrome.

In total, 2,318,706 patients with CHD were examined; of them, 61,101 (2.6%) had atrioventricular septal defect. The incidence of hospitalisation in infants with atrioventricular septal defect ranged from 4.5 to 7.5% of all infants hospitalised with CHD per year. A total of 33,453 (54.7%) patients were associated with Down syndrome. Double outlet right ventricle, coarctation of the aorta, and tetralogy of Fallot were the most commonly associated with CHD in 6.9, 5.7, and 4.3% of patients, respectively. Overall atrioventricular septal defect mortality was 6.3%. Multivariate analysis revealed that prematurity, low birth weight, pulmonary hypertension, and heart block were associated with mortality. Down syndrome was associated with a higher incidence of pulmonary hypertension (4.3 versus 2.8%, p < 0.001), less arrhythmia (6.6 versus 11.2%, p < 0.001), shorter duration for mechanical ventilation, shorter hospital stay, and less perioperative mortality (2.4 versus 11.1%, p < 0.001).

Trends in atrioventricular septal defect hospitalisation had been stable over time. Perioperative mortality in atrioventricular septal defect was associated with prematurity, low birth weight, pulmonary hypertension, heart block, acute kidney injury, and septicaemia. Down syndrome was present in more than half of atrioventricular septal defect patients and was associated with a higher incidence of pulmonary hypertension but less arrhythmia, lower mortality, shorter hospital stay, and less resource utilisation.

The association of atrioventricular septal defect and transposition of the great arteries is very rare. As a rule, these patients have unbalanced ventricles. However, there have been no studies describing the results of single-ventricle palliation in these children.

All children who underwent surgery with a diagnosis of atrioventricular septal defect and transposition of the great arteries were included in the study. Data were obtained from medical records.

A total of 38 patients with atrioventricular septal defect and transposition of the great arteries underwent single-ventricle palliation at the study institution between 1971 and 2016. The mean follow-up was 12.4 years (median: 14.6 years, range 2–43.3 years). Most children had unbalanced atrioventricular septal defect (94.7%, 36/38). Survival was 67.6% (95% confidence interval [CI]: 50.0–80.2%) at 10 years and 57.8% (95% CI: 38.0–73.4%) at 20 years. By 10 years, 58.6% (95% CI: 40.8–72.7%) had progressed to Fontan completion, while 32.5% (95% CI: 18.2–47.6%) had died. In patients achieving Fontan completion, 20-year event-free survival was 73.3% (95% CI: 34.8–91.3%), while 5.0% (95% CI: 0.4–20.5%) had undergone cardiac transplantation and 21.7% (95% CI: 3.2–50.8%) had undergone takedown of the Fontan circulation. Freedom from atrioventricular valve surgery was 57.0% (95% CI: 37.2–72.7%) at 10 and 20 years.

The association of atrioventricular septal defect and transposition of the great arteries is very rare, and most of these children have unbalanced ventricles. Single-ventricle palliation results in 25-year overall survival of 50%. However, in patients, who had Fontan completion, survival was 75% at 25 years after Fontan operation.