Syncope and Cannabis: hypervagotonia from chronic abuse? A case report and literature review

Abstract

Background: Cannabis is the most consumed drug worldwide and number of users is increasing, particularly among youth. Moreover, cannabis potential therapeutic properties have renewed interest to make it available as a treatment for a variety of conditions. Albeit rarely, cannabis consumption has been associated with cardiovascular diseases such as arrhythmias, myocardial infarction (MI) and potentially sudden death.

Case presentation: A 24-year-old woman presented to the emergency department sent by her cardiologist because of a recent finding of a 16 seconds asystole on the implantable loop recorder (ILR) she implanted 7 months before for recurrent syncopes. She declared that she is a heavy cannabis user (at least 5 cannabis-cigarette per day, not mixed up with tobacco, for no less than 12 years) and all syncopes occurred shortly after cannabis consumption. 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. 24 months follow-up period was uneventful.

Conclusions: Cannabis cardiovascular effects are not well known and, although rare, among these we find ischemic episodes, tachyarrhythmias, symptomatic sinus bradycardia, sinus arrest, ventricular asystole and possibly death. Because of cannabis growing consumption both for medical and recreational purpose, cardiovascular diseases associated with cannabis use may become more and more frequent. 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. Clinicians should be aware of the increased risk of cardiovascular complications associated with cannabis use and should investigate its consumption especially in young patients presenting with cardiac dysrhythmias.

Keywords: Asystole; Cannabis; Cardiac pace-maker; Cardiovascular effects; ILR implantation; Recurrent Syncope.

Fig. 1

16 seconds asystole recorded by the ILR occurred around 1:00 a.m. while the patient was sitting, watching television

Fig. 2

One of the several ECG showing a wandering pacemaker with a low atrial rhythm (also known as coronary sinus rhythm). We speculate that this resting ECG suggests a tonically active parasympathetic status on the conduction system of the heart

Fig. 3

Wandering pacemaker followed by a blocked atrial wave at telemetry, occurred while the patient was sleeping (04.45 am)