Infectious endocarditis in idiopathic hypertrophic subaortic stenosis: report of three cases and review of the literature.

Three cases of infective endocarditis (IE) occurringg in patients with idiopathic hypertrophic subaortic stenosis (IHSS) are described. A review of the literature reveals the IE occurs in about 50 percent of the patients suffering from IHSS. It appears to complicate the natural history of the severe cases, at least as it appears from hemodynamic studies, being precipitated by the same factors and caused by the same infective organisms as in valvular heart disease. It has the same clinical picture and outcome, although the appearance of new murmurs was more common than in other types of heart disease complicated by IE, and indicated the same poor prognosis. The infection seems to involve both the aortic and the mitral valve, with equal frequency, and less commonly the ventricular outflow tract. The need for IE prophylaxis in cases of IHSS is stressed.