Results of surgery for hypertrophic obstructive cardiomyopathy.

Between 1971 and March 1986, 61 patients underwent surgery for hypertrophic obstructive cardiomyopathy. Age at operation varied from 3.5 to 76 years (mean 38). The standard approach was a generous transaortic myectomy. One-quarter of the patients underwent concomitant repair of associated lesions. There was one operative and two late deaths, for an actuarial 5 years survival 93% (+/- 8%). Average follow-up is 3 years per patient. Sixty-four percent of these patients are asymptomatic and another 30% were in New York Heart Association class II. Persistent symptoms were usually related to arrhythmias. Early atrioventricular block did not occur, but two patients were paced for complex arrhythmias 3 and 4 years after surgery. Hemodynamic studies (n = 22), two-dimensional echocardiographic (n = 47), and Doppler assessments (n = 23) demonstrated a left ventricular outflow tract pressure gradient of 70 and 14 mm Hg before and after surgery, respectively, left ventricular diastolic pressure of 18 and 14 mm Hg, percent of patients with mitral regurgitation of 70% and 30%, percent of patients with systolic anterior motion of 100% and 35%, and percent of patients with aortic insufficiency of 9% and 49%. Eight-six percent of the patients catheterized had no resting obstruction. Subaortic myectomy produces symptomatic improvement by reducing the left ventricular outflow tract pressure gradient, mitral regurgitation, and left ventricular end-diastolic pressure, and probably improves longevity.