A Rare Case of Second Degree Mobitz Type II AV Block Associated with Cocaine Use

Abstract

Cocaine is a commonly abused illicit drug in the United States. The complex effects of cocaine on the conduction system of the human heart has not been completely understood. Cocaine acts as a sympathomimetic by inhibition of reuptake of neuronal catecholamines, leading mostly to tachyarrhythmias on presentation. However, cocaine also exerts other effects on the conduction system including sympathomimetic, sino-bradycardic as well as local anesthetic properties. While Multiple cases of atrioventricular (AV) conduction blocks including first degree AV block, Mobitz type I and third degree AV blocks have been previously reported, we hereby present the first case report of cocaine- induced Mobitz type II second degree AV block. This case occurred in a 55 year old woman who presented with retrosternal chest pressure and tested positive for cocaine abuse as documented by urine toxicology test. Patient spontaneously converted to normal sinus rhythm the following day post admission to the hospital. Cocaine is known to inhibit sodium channels and thus has been known to decrease SA node automaticity and conduction via AV node. Electrophysiology studies have previously confirmed cocaine mediated delay in impulse conduction and repolarization. Though rare, physicians should be aware of the possibility of bradyarrhythmias associated with cocaine abuse in order to apply standard therapy such as pacemaker in the event of non-resolution of this serious arrhythmia.