Congenital left ventricular inflow obstruction: is the outcome related to the site of the obstruction?

Between 1978 and 1987, 39 patients aged 1 day to 15 years underwent surgery for symptomatic left ventricular inflow obstruction. Four diagnostic groups were identified: cor triatriatum (6 patients), supravalvar mitral membrane (SVMM) with a normal mitral valve (7 patients), SVMM with an abnormal mitral valve (9 patients) and mitral stenosis (17 patients). Associated cardiac anomalies occurred in 26 patients (67%). There were 8 deaths (21%), 3 in patients with SVMM and an abnormal mitral valve and 5 in patients with mitral stenosis. Survival for patients with normal mitral valves was significantly better than that for patients with abnormal mitral valves (13/13 vs 18/26, P less than 0.05). There was also high morbidity in patients requiring prosthetic mitral valve replacement. These data suggest that the outcome of surgical treatment for left ventricular inflow obstruction may be predicted according to the site of the obstruction. This is best determined preoperatively by cross-sectional echocardiography which allows optimal planning of surgical strategy.