Case summary
A 26 years old young medical intern with history of chronic marijuana usage presented with complains of dizziness and recurrent syncope. Heart rate at presentation was 42 beats per minute and rest of the physical examination was unremarkable. There was high grade atrioventricular block in the Electrocardiogram (ECG) and subsequent electrophysiological (EP) study showed high grade supra-hisian (nodal)atrioventricular block with mildly prolonged his-ventricular (HV) interval. Urinary screen was positive for Δ9-tetrahydrocannabinol (THC). After ruling out other possible causes, diagnosis of high-grade AV block due chronic marijuana use was made. Dual chamber pacemaker was implanted, and patient was discharged in stable condition. The heart rhythm completely improved at three-month follow-up.