Familial hypertrophic cardiomyopathy complicated by complete atrioventricular block.

We described a patient with familial non-obstructive hypertrophic cardiomyopathy and complete atrioventricular block. A 27-year-old male was admitted to our institution with syncope. Electrocardiography demonstrated complete atrioventricular block. Two-dimensional echocardiography revealed non-obstructive hypertrophic cardiomyopathy. A temporary transvenous ventricular pacemaker was inserted urgently, and subsequently replaced by a permanent dual-chamber pacemaker. Meanwhile, non-obstructive hypertrophic cardiomyopathy was diagnosed in the mother, the aunt and one of the brothers of the patient in the screening of the family, but atrioventricular conduction block was not detected in them. In the electrophysiological study of the mother, inducible ventricular tachycardia was detected. The reason for diversity of the arrhythmias in the members of the same family with hypertrophic cardiomyopathy may be explained by penetrance. The phenotype of the familial hypertrophic cardiomyopathy is influenced by factors varying the penetrance, such as age and gender.