640 Cannabis abuse and syncope
Authors: Licciardi Marco , Utzeri Elena , Marchetti Maria Francesca , Pittau Roberta , Campana Nicola , Orani Elena , Nissardi Vincenzo , Demelas Roberta , Maiani Silvia , Meloni Luigi , Montisci Roberta 
Published: December 2021

Abstract

Aims
Cannabis (marijuana) is the most consumed drug worldwide, counting roughly 200 million users in 2019 (4% of the global population). Once illegal in most of the world countries, cannabis is now legal for medical and recreational use in several states. During the last 20 years, we have observed a growing decriminalization wave parallel with an increase number of consumers: it is therefore mandatory not only for the cardiologists but for every physician to be aware of marijuana potential cardiovascular adverse health effects. With this paper, we present a case report of cannabis induced 16 s implantable loop recorder (ILR) recorded asystole from hypervagotonia in a 24-year-old heavy marijuana consumer. We focus on the infrequently reported association between syncope and chronic marijuana use and we try to explain the underlying mechanisms against the background of the current literature.

Methods and results
A 24-year-old presented to the emergency department sent by her cardiologist because of a recent finding of a 16 s asystole on the ILR she implanted 7 months before for recurrent syncopes. She openly declared that she is a heavy marijuana user (at least 5 cannabis-cigarette per day, not mixed up with tobacco, for no less than 12 years). She had a history of at least two spontaneous atypical syncopal episodes and a multitude of pre-syncopal episodes. Before being hospitalized, she underwent several diagnostic tests excluding a neurological etiology and, upon outpatient regimen, she begun a cardiology evaluation which lead to the ILR implantation. While watching TV at late night, the second prodrome-less syncopal episode occurred and a 16-s asystole was found on the ILR. During hospitalization, the patient was closely monitored and we evaluated basic autonomic function tests, carotid sinus massage, echocardiography, exercise stress test, and 24 h telemetry. Following the results of the exams, we considered a heart conduction system anomaly unlikely. Finally, the patient underwent a toxicological and a psychiatric evaluation, where she strongly expressed not wanting to abandon cannabis abuse. After a collective discussion with the heart team, syncope unit, electrophysiologists, and toxicologist, we decided to implant a dual chamber pacemaker with a rate response algorithm due to the high risk of trauma of the syncopal episodes.

Conclusions
Cannabis cardiovascular effects are not well known; among these we find ischaemic episodes, tachyarrhythmias, symptomatic sinus bradycardia, sinus arrest, and ventricular asystole. In the light of the poor literature, we believe that cannabis may produce opposite adverse effects depending on the duration of the habit. Acute administration increases sympathetic tone and reduces parasympathetic tone; conversely, with chronic intake an opposite effect is observed: repetitive dosing decreases sympathetic activity and increases parasympathetic activity. Physicians should be aware of the effects that cannabis produces upon the cardiovascular system: this could avoid expensive, prolonged hospitalizations, and needless diagnostic tests.