EXPERIMENTAL AND CLINICAL cardiomyopathies are characteristically associated with progressive cardiac failure and death.' Cardiac function is often impaired long before clinical symptoms occur. In congestive cardiomyopathy hemodynamic and angiographic evaluations reveal elevated enddiastolic pressures, abnormal ventricular function curves, and diffuse hypokinetic contraction patterns.2 However, idiopathic hypertrophic subaortic stenosis (IHSS), a primary cardiac myopathic disorder, is paradoxically associated with increased myocardial contractility. The left ventricle in this entity is hyperdynamic and angiographic ejection fractions are frequently in excess of 0.70.3 Histologic studies of the myocardial cells in IHSS have shown them to be multinucleated, bizarre, and misaligned," 5 thus confirming that this is a myopathic disease. These abnormalities are restricted most often to the interventricular septum." Furthermore, disproportionate