Congenital mitral stenosis is defined as any obstacle to diastolic filling of the left ventricle due to abnormal development of the structures that form the mitral apparatus (ring, immediately supravalvular area, cords and pillars). It is a rare congenital malformation, its prevalence is estimated at 4 in 1000 children diagnosed with congenital heart disease and it constitutes 0.6 to 1.2% of autopsied congenital heart defects.

Clinical,epidemiological and prognostic aspect of CMS.

We conducted a retrospective study collected in the cardiology department of CHU of Casablanca, between September 2009 and January 2018, involving 26 patients. Inclusion Criteria: Included in the study were all children referred to our institution for cardiac evaluation and diagnosed with congenital mitral stenosis at echocardiography.

During the study period we diagnosed 2678 congenital heart defects. CMS was present in 26 patients, a prevalence of 0.97%. Population consisted of 13 boys and 13 girls, a sex ratio of 1 and the average age was 6 years. The symptomatology was dominated by dyspnea (17 cases) and recurrent bronchitis (8 cases). The echocardiography found an isolated RMC in 3 cases, the etiology were dominated by the supramitral ring(14 cases) and parachute mitral valve(8 cases). The CHD associated with RMC was VSD (9 case). The others associated with RMC were: coarctation of the aorta (6 cases), TGA (4 cases), pulmonary stenosis (4 cases), aortic bicuspid (4 cases), left superior vena cava (3 cases), ASD (2 cases), supra valvular aorticstenosis (2 cases), PDA (2cases), Shon syndrome(1 cases). Pulmonaryhypertension was present in 50%, 2 of which were in Eisenmenger. Surgery was indicated in 13; 4 benefited from curative surgery;4 are lost sight of; 4 patients with CMS considered to be unstiffened had no indication for surgery. 5 died, 1 of them inoperative, 3 refusing their parents surgery and one in extra hospital. Overall, there was a good surgical outcome in patients who received curative surgery.