Idiopathic hypertrophic subaortic stenosis: long-term surgical results.

The results of surgery in 21 patients with I.H.S.S. are reported. Dyspnea, angina pectoris and syncope were the most common symptoms in decreasing frequency. Before the operation, 5 patients were in New York Heart Association's functional class II, 10 in class III and 6 in class IV. The mean resting peak systolic pressure gradient was 66 mm Hg in 20 patients and mean left ventricular end-diastolic pressure was 14 mm Hg in 19 patients. The ventriculoseptomyectomy accomplished through a transaortic approach is the procedure of choice. The operative mortality rate was 14% (3 of 21 patients). There were 2 late deaths from congestive heart failure. Any sudden death did not occur. The remaining 16 patients have been followed up for a mean of 75 months (range 12 months to 11 years), 11 patients are in functional class I, 4 in class II and 1 in class III. Complete left-bundle-branch block occurred in 3 patients. Our study with a long post-operative follow-up period, documents that surgery results in good to excellent alleviation of symptoms in survivors. The elevated pre-operative left ventricular end-diastolic pressure has a significantly poor prognosis. We currently recommend surgery for the symptomatic patients who have not responded to medical therapy, not late in the symptomatic course of the disease.