Introduction: Cannabis use results in elevation of heart rate and blood pressure immediately after use, primarily due to sympathetic nervous system stimulation and parasympathetic nervous system inhibition. These effects may precipitate cardiac dysrhythmia. The objective of our study was to analyze systematically the pertinent medical literature regarding the putative association between cannabis use and cardiac dysrhythmia. Methods: We queried PubMed, Google Scholar, and OpenGrey, and reviewed results for relevance. We graded clinical trials, observational and retrospective studies, case series and reports using Oxford Centre for Evidence-Based Medicine guidelines. Results: The relevant publications identified included one Level I systematic review and meta-analysis of six human studies, 16 Level II studies with 6,942 subjects, nine Level III studies with 3,797,096 subjects and two systematic and scoping reviews with 30 cases. Cannabis-induced tachycardia was highlighted in 17 of 28 (61%) Level I–III articles followed by a generalized description of dysrhythmia in eight (29%). Specific dysrhythmias noted in the Level I–III articles included atrial fibrillation, atrial flutter, atrioventricular block, premature ventricular contractions, premature atrial contractions, ventricular tachycardia, and ventricular fibrillation. Other reported findings on electrocardiogram included ST segment elevation, P, and T wave changes. Only one Level III study reported a decreased risk of atrial fibrillation from cannabis use in patients hospitalized for heart failure (Odds ratio = 0.87). There were 39 case series (Level IV) and case reports (Level V) with 42 subjects. Average age was 30 ± 12 years, and only ten (24%) were female. The most common dysrhythmia mentioned in the Level IV and V articles was ventricular fibrillation (21%), followed by atrial fibrillation (19%), ventricular tachycardia (12%), third degree atrioventricular block (12%), and asystole (12%). There were four cases (10%) of symptomatic bradycardia. Notable electrocardiographic changes included ST segment elevation (29%), Brugada pattern in leads V1, V2 (14%), and right bundle branch block (12%). There were eight cases of cardiac arrest, of whom five expired. Conclusion: Cannabis use is associated with increased risk of cardiac dysrhythmia, which is rare but may be life-threatening. Clinicians and nurses should inquire about acute and chronic cannabis use in their patients presenting with tachycardia, bradycardia, dysrhythmia, chest pain, and/or unexplained syncope. Patients who use cannabis should be educated on this deleterious association, especially those with underlying cardiac disease or risk factors.
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