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 diseasesand it is the congenital heart disease which is mostly associated with chromosomic abnormalities especially trisomy 21.

The mane objective of this study is to assess features of AVSD in trisomic patientsand the prognostic impact of trisomy 21 in AVSD.

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

313 patients were included. ACSD was associated with trisomy 21 in 30.2%. The comparison of frequency of trisomy 21 regarding the type of AVSD and according to Rastelli classificationfor complete AVSDwas not significant with p values respectively of 0,110 and 0,086. We noted less pulmonary arterial hypertensions in trisomic patients (33%), par rapport compared to non trisomic patients (33% vs. 67%;P=0,026).The study of the association between trisomy 21 and Eisenmenger syndromehasn’t shown a statistical difference (P=1,000), the presence of trisomy 21 didn’t cause more mortality compared to eusomic patients (P=0,110), trisomic patients who did benefit from surgical curehad less mortality compared to non treated patients (28,6% vs. 87,5%; P=0,005).

AVSD, particularly in its complete for is a pathology which is strongly associated with trisomy 21. This shows the importance of the diagnosis and genetic counselling. The treatment is essentially surgical and should be done early.