Idiopathic hypertrophic subaortic stenosis in the young.

Thirty-six young patients with idiopathic hypertrophic subaortic stenosis were studied. Twenty-seven patients were male and 9 female, and their mean age was 11.3 years (range 5 months to 20 years). Twenty-three patients (64 percent) had symptoms, the most common being dyspnea, angina and syncope. Diagnostic difficulties were encountered frequently in younger patients, especially those with right heart involvement, and in asymptomatic patients with murmurs suggestive of other cardiac defects. Patients were classified retrospectively into three groups on the basis of management. The first group consisted of 16 patients who were operated on; 4 of these patients died, 1 operatively and 3 suddenly late postoperatively (at 1.6, 2 and 10 years). The 12 long-term survivors (average follow-up period 6.2 years) have had good relief of symptoms. The second group comprised seven patients treated with propranolol; none of these died. The 13 patients in the third group received no therapy; 7 of these patients died, 6 suddenly and 1 from congestive cardiac failure. Idiopathic hypertrophic subaortic stenosis is a serious disorder that may present at any age and that may be difficult to diagnose. All patients with this disorder should be treated with propranolol; surgical intervention, although it does not totally abolish the risk of sudden death, appears to offer symptomatic improvement in most cases over a long-term follow-up period.