OBJECTIVE The purpose of this study was to determine whether two-dimensional and Doppler echocardiography are predictive of clinical outcome in patients with hypertrophic obstructive cardiomyopathy who undergo septal myectomy. BACKGROUND Surgical myectomy provides excellent relief of symptoms in most patients with hypertrophic obstructive cardiomyopathy who are severely symptomatic despite medical therapy. There is a subset of patients who will remain symptomatic even after operation. Because comprehensive two-dimensional and Doppler echocardiography can define the range of anatomic and associated pathophysiologic abnormalities, it was hypothesized that preoperative echocardiographic variables may be predictive of clinical outcome after septal myectomy. METHODS The clinical, electrocardiographic (ECG), echocardiographic and surgical data of 47 adult patients with hypertrophic cardiomyopathy who underwent isolated septal myectomy from 1986 to 1992 were analyzed. Specific symptoms were evaluated both preoperatively and at 1 year postoperatively. Electrocardiography and echocardiography were performed preoperatively and postoperatively. The ECG and echocardiographic variables were analyzed to determine whether any were predictive of residual symptoms 1 year postoperatively. RESULTS The mean [+/-SD] age of the patients was 47 +/- 15 years. All were New York Heart Association functional class III or IV. Dyspnea was present in all 47 patients and was severe in 70%. Most patients experienced symptomatic improvement at 1 year; dyspnea persisted in 26 patients (55%). The preoperative echocardiographic variables of asymmetric hypertrophy, severe systolic anterior motion of the mitral leaflet(s) and prolonged isovolumetric relaxation time were independent predictors of mild or no residual dyspnea postoperatively. CONCLUSIONS This initial study shows that the preoperative echocardiographic variables of asymmetric hypertrophy, severe systolic anterior motion of the mitral leaflet(s) and prolonged isovolumetric relaxation time can identify patients who are most likely to benefit from septal myectomy.