Hypertrophic Cardiomyopathy with masked Atrioventricular Block. Report of 2 cases

Abstract

Background. Hypertrophic cardiomyopathy is the most common genetic cardiac disorder in Algeria, although syncope is often caused by ventricular arrhythmias or left outflow tract obstruction, it may also, be related to complete atrioventricular block; the latter is rarely reported in the literature, the diagnosis is not so obvious and should be thoroughly researched in presence of syncope. We report two cases of patients with hypertrophic cardiomyopathy and atrioventricular block revealed by syncope. Cases’ presentation. We reported two patients who presented hypertrophic cardiomyopathy, with recurrent syncope; one patient presented accessory the pathway which masked the complete atrio ventricular block and the other patient presented alternating occurrence of right bundle branch block and left bundle branch block at the ECG monitoring over a 48 hours. Echocardiography showed hypertrophy of left ventricular walls, but no left ventricular outflow tract gradient was detected. Extensive fibrosis especially in the septum was detected by late gadolinium enhancement. The two patients were implanted with dual-chamber pacemakers. During follow up, one patient had developed refractory heart failure and died in 2014. Conclusions. Accessory pathway may mask complete atrioventricular block, also alternating bundle branch block could be the only proof of complete atrioventricular block. Fibrosis is the principal the substrate of reentry phenomenon, but septal fibrosis can also damage the atrioventricular conduction system. Non-obstructive hypertrophic cardiomyopathy could be related to fibrosis, and/or asynchrony.

Keywords

• convulsive syncope
• sudden cardiac death
• alternating bundle branch block
• accessory pathway