Evaluating the Association Between Marijuana and Tobacco Use and the Risk of Developing Atrial Fibrillation.

Background Marijuana and tobacco use have become increasingly prevalent, raising concerns regarding their cardiovascular effects. Atrial fibrillation (AF), a common cardiac arrhythmia associated with increased morbidity and mortality, has been linked to substance use. Nicotine in tobacco products increases sympathetic activity, heart rate, and blood pressure, predisposing individuals to arrhythmias. Similarly, tetrahydrocannabinol (THC), the primary psychoactive component of marijuana, has been associated with cardiac ion channel modulation and QT interval prolongation, although this continues to be debated. This study aimed to evaluate and compare the association between marijuana and tobacco use and the risk of developing AF. Methods A retrospective cohort study was conducted using the TriNetX database. Two cohorts were identified: individuals aged 18-65 with cannabis abuse diagnoses and no history of tobacco use, and individuals with documented tobacco use disorder and no documented cannabis exposure. Index events were defined as the first qualifying diagnosis. AF incidence was assessed beginning one day after the index event with no predetermined end date. Propensity score matching was performed to balance baseline demographic variables. Outcomes were evaluated using measures of association, survival analysis, and hazard ratios. Results After propensity score matching, the cannabis cohort included over 500,000 patients, and the tobacco cohort exceeded 1.5 million patients. AF incidence was 1.8% in the cannabis cohort compared to 2.0% in the tobacco cohort, demonstrating a statistically significant risk difference of -0.002 favoring cannabis exposure. However, the effective size of this remained small and is thus a limitation of this study. Additionally, tobacco use disorder and marijuana usage encompass two different levels of consumption, which means that the groups distinctly vary in their substance usage, which was not further quantified in this study. Mean follow-up duration was 1,435 days for the cannabis cohort and 1,696 days for the tobacco cohort. Hazard ratio analyses further supported an increased AF risk associated with tobacco use. Conclusions Tobacco use disorder was associated with a higher incidence of AF than with marijuana. Although this is a retrospective cohort study based on ICD-10 codes and therefore has limitations to generalizability, it suggests a potential association that should be further evaluated in randomized control trials. These findings provide important insights for clinicians and public health initiatives addressing substance-related cardiovascular risk and highlight the need for further longitudinal investigations.