Cannabis use and incident atrial fibrillation in a longitudinal cohort

Background Cannabis use is increasing worldwide. While prior studies have reported an association between cannabis use and a higher risk of atrial fibrillation (AF), most were cross-sectional and generally relied on diagnostic coding to identify cannabis users, which may not be representative of the typical, recreational cannabis user. Objective To examine the association between recreational cannabis use and lifetime AF risk. Methods We evaluated the AF risk of participants of the UK Biobank cohort who completed the cannabis use lifestyle questionnaire. Cannabis exposure was categorized as "Occasional Use" for less than 100 times used, "Frequent Use" for more than 100 times used, and "Never" users. AF events were identified using International Classification of Diseases (ICD) codes. Cox models were used to estimate the hazard ratios (HR) between cannabis use and incident AF and were subsequently adjusted for age, sex, race, alcohol, coffee, smoking, education, and baseline cardiovascular comorbidities. Results A total of 150,554 participants (mean 63.4 ± 7.7 years, 57.4% female, and 22.2% using cannabis at least once) were followed for a mean 6.1 ± 0.6 years. After multivariable adjustment, there were no statistically significant differences in incident AF among occasional users (HR 0.98, 95% CI 0.89 to 1.08) nor frequent users (HR 1.03, 95% CI 0.81 to 1.32) compared to never users. Conclusions Among a large, prospective cohort, there was no evidence that cannabis use was associated with a higher risk of incident AF. An evaluation of cannabis ingestion methods and quantification was not possible using the current dataset.