Hypertrophic apical cardiomyopathy: a subtype of hypertrophic cardiomyopathy.

: This is the first report of hypertrophic apical cardiomyopathy outside of Japan. Electrocardiographic, vectorcardiographic, echocardiographic, hemodynamic and angiographic investigations support the view that this entity is a subset of hypertrophic cardiomyopathy that differs from hypertrophic obstructive cardiomyopathy and left-ventricular cavity obliteration. The ECG recorded giant negative T waves associated with prominent R waves in the precordial leads and septal Q waves were absent, with a normal mean QRS axis in the frontal plane. The vectorcardiogram showed a QRS loop oriented to the left anteriorly and inferiorly, while the T loop was characteristically discordant, elongated and situated in the right posterior quadrant. An M-mode ECG scan along the left-ventricular long axis revealed a marked increase in both septal and posterior wall thickness and excursions toward the apex. A characteristic spadelike configuration was observed in the left ventriculogram at end-diastole. Pressure studies at rest and after ventricular ectopic beats and isoproterenol provocation revealed no significant peak systolic pressure gradient within the left ventricle. This may have certain therapeutic implications.