The outcome of surgical treatment of hypertrophic obstructive cardiomyopathy. Experience over 15 years.

From 1972 through 1987, 115 patients between the ages of 1 and 83 years (mean, 44.5 years) underwent operation for hypertrophic obstructive cardiomyopathy. Methods of relief of left ventricular outflow obstruction were septal myectomy/myotomy (n = 109), mitral valve replacement (n = 4), and myectomy/myotomy plus mitral valve replacement (n = 2); concomitant procedures included coronary artery bypass (n = 19) and aortic valve replacement (n = 9). Systolic gradient (peak-to-peak) from the left ventricle to the aorta decreased from 70 +/- 38 mm Hg (mean +/- standard deviation) to 9 +/- 11 mm Hg. There were six hospital deaths, for an overall operative risk of 5.2%; one death occurred among 83 patients less than age 65 years (operative risk, 1.2%), and five deaths occurred in 32 older patients (operative risk, 15.6%; p = 0.008 for difference between age groups). Four (22.2%) of 18 patients with a residual gradient greater than 15 mm Hg died, compared with two (2.1%) of 97 patients with a lower gradient (p = 0.003). Follow-up ranged from 0.5 to 16 years (mean, 5.1 years), and 5-year actuarial survival rate, including hospital deaths, was 84% +/- 4%. The 5-year survival rate was decreased in patients who had operative procedures other than myectomy/myotomy (69% versus 91%, p less than 0.005) and in patients aged 65 years or older (54% versus 93%, p less than 0.005). No correlation was found between preoperative symptoms, functional class, left ventricle-aorta pressure gradient, or mitral valve insufficiency and operative or late mortality. Preoperative symptoms were relieved in 57 (76%) of 75 patients with dyspnea, 49 (83%) of 59 patients with angina, and 22 (96%) of 23 patients with syncope. This experience confirms the effectiveness of operation for relief of symptoms in patients with the obstructive form of hypertrophic cardiomyopathy. The current operative mortality rate is low, especially in patients less than 65 years of age (1.2%). Our experience suggests that incomplete relief of left ventricular outflow obstruction may increase the risk of early postoperative death.