Chronic cannabis smoking linked to high-grade heart block requiring pacemaker in 26-year-old

Electrophysiology study revealed high-grade supra-Hisian AV block with prolonged His-ventricular interval in a young man with chronic cannabis use and no other identifiable cause. The arrhythmia did not resolve after three months, and a dual-chamber pacemaker was required. This is the first report of electrophysiologic localization of cannabis-induced conduction block.

Clinical case report of a 26-year-old male with chronic cannabis smoking who presented with dizziness and syncope. ECG, electrophysiology study, urinary THC metabolite testing, and follow-up evaluation were performed after ruling out other causes.

While cannabis-associated tachyarrhythmias are well-documented, bradyarrhythmias are rare. The prolonged HV interval suggests cannabis may directly affect the cardiac conduction system rather than just increasing vagal tone, as previously assumed.

This case challenges the assumption that cannabis-related bradycardia is solely vagally mediated. The prolonged HV interval and persistent nature of the block suggest potential direct toxic effects on the cardiac conduction system through CB1 receptors.

Single case report. Cannot definitively prove cannabis caused the conduction block. Possible confounders from unknown adulterants. No long-term follow-up beyond three months.