Apical hypertrophic cardiomyopathy: clinical and two-dimensional echocardiographic assessment.

Of 965 patients with hypertrophic cardiomyopathy evaluated by echocardiography at the National Institutes of Health during a 7-year period, 23 (2%) had a nonobstructive morphologic form, in which wall thickening occurred predominantly in the apical (distal) portion of the left ventricle. The patients ranged in age from 15 to 69 years (mean, 37) and were predominantly male (14 patients) and white (only 1 was of oriental descent). Fifteen patients had significant functional limitation, which was usually caused by exertional dyspnea and fatigue. Several electrocardiographic patterns were identified in the study group, but only 4 of these patients showed "giant" negative T waves. Only 3 patients had a morphologic expression of apical hypertrophy that closely resembled that described in Japanese patients--that is, hypertrophy that was particularly localized and confined to the true left ventricular apex (2 of these patients had giant negative T waves). Hence, hypertrophy located predominantly in the distal left ventricle was uncommon in our primarily North American patient population with hypertrophic cardiomyopathy. Most of our patients showed morphologic and clinical features that were dissimilar to those found previously in Japanese patients with apical hypertrophy.