Atrioventricular septal defect (AVSD) is a complex heart malformation affecting the lower part of atrial septum, the highest part of ventricular septum, mitral and tricuspid valves.It represents 3 to 7.3 of congenital heart diseases and it is the congenital heart disease which is mostly associated with chromosomic abnormalities especially trisomy 21.

The main objective of this study is to assess the prognostic factors and the overall mortality rate of patients with AVSD.

Descriptive transversal retrospective and monocentric study conducted on a period of 10 years between December 2008 and December 2018. Were included all patients presenting with AVSD confirmed by echocardiography and followed-up in the congenital heart diseases unit of our department.

A total of 313 patients were included. The median age was 9 months [3 days;56 years]. Female gender represented 51.4%. Complete ACSD was more common (77%), followed by partial ACSD (19.2%). Overall mortality was 44.7%. Among these deaths 50.8% occurred during the first 6 months of life. Complete ACSD was associated with higher mortality (52.5% of deaths) compared to other types of ACSD P=0.002. Operated patients had a mortality of 28.9%, significantly lower than non-operated (64.9%) P<0.001. Survival is as much improved as the surgical cure was conducted earlier. Before the age of 3 months: 50% of survivors if operated vs. 10% if not operated P=0.025. Deceased patients had lower oxygen saturation than the survivors P=0.048. Pulmonary arterial hypertension or T21 had no effect on mortality. The combination with other congenital heart defects with ACSD did not show a statistically significant impact on mortality.

AVSD, particularly in its complete form is a serious condition with a poor prognosis. This shows the importance of the diagnosis and genetic counselling. The treatment is essentially surgical and when it is early, it considerably improves the prognosis.