Relief of left ventricular outflow obstruction by cibenzoline in a patient with Fabry's disease--a case report.

A 46-year-old man was admitted for further evaluation of exertional chest discomfort. One family member had experienced sudden death, and 2 others had died of heart failure, including 1 known to have had Fabry's disease. The patient was also diagnosed with Fabry's disease, based on reduced leukocyte alpha-galactosidase A activity, 2.0 nmol/mg protein/hour, as well as endomyocardial biopsy findings of marked sarcoplasmic vacuolization of cardiac muscle cells by light microscopy and lamellated "zebra bodies'' in the cytoplasm shown by electron microscopy. Echocardiography disclosed marked left ventricular hypertrophy and systolic anterior motion of the mitral leaflets. On cardiac catheterization, a left ventricular peak systolic outflow gradient of 50 mm Hg was noted; this decreased to 10 mm Hg following intravenous administration of 100 mg of cibenzoline. It is imperative to recognize the existence of cases with Fabry's disease associated with left ventricular outflow obstruction.