Sudden unexpected cardiac death is the most devastating feature of the natural history of hype~rophic cardiomyopa- thy and in many patients is the first clinical manifestation of the disease (1-7). Although left ventricular hypertrophy

Sudden unexpected cardiac death is the most devastating feature of the natural history of hype~rophic cardiomyopathy and in many patients is the first clinical manifestation of the disease (1-7). Although left ventricular hypertrophy appears to be an important determinant of many functional features of hypertrophic cardiomyopathy, the reialion between the magnitude of hypertrophy and the occurrence of sudden cardiac death has not been defined. To investigate the relation between these two co ponents of the disease, we assessed the extent of left ventricular hypertrophy (by two-