Hypertrophic obstructive cardiomyopathy: ten- to 21-year follow-up after partial septal myectomy.

This study reviews the outcome in 36 consecutive patients who survived partial septal myectomy for hypertrophic obstructive cardiomyopathy operated on between 1960 and 1972. All patients were followed up until death or until June 1981 (mean 13.4 years). Of the 26 survivors, 17 had been more than mildly symptomatic preoperatively, but only 1 remained so postoperatively. The operation was effective in relieving the obstruction (peak systolic pressure gradient reduced from 79 to 8 mm Hg [p less than 0.001]), and mitral regurgitation was relieved. No survivor's symptoms worsened, but 10 died late--4 suddenly, 5 from congestive heart failure, and 1 from a malignancy. The 10-year survival rate was 77%. No correlation with outcome was found with respect to age, surgical approach, preoperative functional class, pressure gradient, left ventricular end-diastolic pressure, or presence of atrial fibrillation, but atrial fibrillation occurring late postoperatively (12 patients) was associated with an increased frequency of late death (7 of 10 late deaths) or continuing New York Heart Association functional class III status. Early or late postoperative complete heart block occurred in 1 patient each. Thus, these results suggest a favorable effect of operation and support continued surgical intervention for appropriate patients.