Electrophysiologic evaluation of patients with hypertrophic cardiomyopathy.

Ten consecutive patients with hypertrophic obstructive cardiomyopathy proven by echocardiography were subjected to detailed electrophysiologic evaluation and 24-hour ambulatory monitoring to detect the spectrum of arrhythmias and to identify their clinical correlates, if any. Two patients presented with syncope and the others with varying grades of dyspnea and angina. Ambulatory monitoring revealed isolated ventricular ectopics in five patients including couplets in two cases and runs of atrioventricular dissociation in two patients. Four patients had a normal study. Electrophysiologic evaluation demonstrated inducible nonsustained ventricular tachycardia in two patients (one with syncope and the other without syncope), short runs of supraventricular tachycardia in one (with a history of syncope), an accessory atrioventricular connexion in one patient (without any inducible arrhythmia), short atrio-His interval with minimal prolongation on incremental atrial pacing in three patients and ventriculoatrial conduction in two patients. A variety of electrophysiologic abnormalities was demonstrated in patients with hypertrophic cardiomyopathy. In two patients with a history of syncope only a nonsustained tachycardia was inducible. Further studies are warranted to find out the significance of these arrhythmias.