Hypertrophic cardiomyopathy presenting with 3rd-degree atrioventricular block.

A 15-year-old boy presented with exercise intolerance and near syncope. Electrocardiography showed 3rd-degree atrioventricular block. He was treated emergently with temporary transvenous ventricular pacing. Two-dimensional echocardiography revealed hypertrophic cardiomyopathy. Subsequently, a permanent, transvenous, dual-chamber pacemaker was implanted. Hypertrophic cardiomyopathy rarely causes complete atrioventricular block. It is particularly unusual for the presenting symptoms of hypertrophic cardiomyopathy to be caused by atrioventricular block. The case report is followed by a review of the pediatric literature on hypertrophic cardiomyopathy with atrioventricular block.