Supramitral ring: good prognosis in a subset of patients with congenital mitral stenosis

Management of congenital stenotic mitral valvular abnormalities remains an important therapeutic challenge. Supramitral ring constitutes a small but inadequately described subset that has a relatively good outcome with appropriate management.

Between 1996 and 2004, 15 patients with supramitral ring were managed in this institution. The demographic and clinical features, diagnostic modalities, morphology of the rings, and the surgical management were studied retrospectively.

Accurate preoperative diagnosis was possible by transthoracic echocardiography in 11 patients (73%). The associated anomalies were ventricular septal defects in 8 patients (53%) and abnormalities of the left ventricular outflow tract in 7 patients (47%). A circumferential supramitral ring, separate from the mitral valve, was present in 8 patients (53%). In the remaining, the ring was attached circumferentially to the anterior and the posterior mitral leaflets and was most densely adherent at the posteroinferior commissure in 4 of these 7 patients (57%). Complete excision of ring was possible in all cases, without damage to the mitral valve. There was 1 in-hospital death (6%). At a mean follow-up of 30 months, 14 survivors continue to do well, with no significant recurrence of mitral stenosis.

Patients with supramitral ring constitute a subset of patients with congenital mitral stenosis who have a relatively good prognosis. In many cases, the supramitral ring is entirely separate from the mitral valve, and when attached, it is usually most prominent at the posteroinferior commissure. In both cases, complete resection is surgically feasible and usually provides lasting relief.