We carried out a detailed clinical, epidemiological, and echocardiographic study in 41 patients ≤14 years of age who were admitted in a public hospital in Salvador, Brazil, with severe rheumatic heart disease.

Mitral insufficiency was severe in 90%, and moderate in 10%, of the patients. A posteriorly directed jet was seen in 93% of the patients. We identified three mechanisms producing the regurgitation: prolapse of the aortic leaflet of the mitral valve in 13 (32%) patients, rupture of tendinous cords in 14 (34%), and a retracted, non-coapting mural leaflet in 14 (34%). The mean ages, with standard deviations, for these three groups were 7.0 (1.6) years, 7.9 (2.2) years, and 10.5 (2.4) years, respectively (p < 0.001). Rheumatic activity was diagnosed in 58.5% of them. Evidence of previous rheumatic fever was present in 54% of patients with prolapse, in all patients with rupture, and in 93% of those with non-coapting leaflets (p = 0.002).

Prolapse of the aortic leaflet, rupture of tendinous cords, and a retracted, non-coapting mural leaflet are the mechanisms responsible for mitral valvar insufficiency in children and adolescents with severe rheumatic heart disease. Prolapse seems to be an early phenomenon in the natural history of rheumatic heart disease, while rupture and non-coaption of the leaflets were associated with older age and signs of chronic rheumatic disease.