Smoking and risk of atrial fibrillation in the REasons for Geographic And Racial Differences in Stroke (REGARDS) study

•Smoking is associated with atrial fibrillation (AF).•This association became non-significant after adjusting for cardiovascular risk factors suggesting possible mediation by these factors in smokers.•Also, there was heterogeneity in the strength of this association among subgroups which may explain the conflicting results in prior studies. Whether smoking increases the risk of atrial fibrillation (AF) remains debatable due to inconsistent reports. We examined the association between smoking and incident AF in 11,047 participants from the REasons for Geographic And Racial Differences in Stroke (REGARDS) Study, one of the largest biracial, population-based cohort studies in the USA. Baseline (2003–2007) cigarette smoking status and amount (pack-years) were self-reported. Incident AF was determined by electrocardiography and history of a prior physician diagnosis at a follow-up examination conducted after a median of 10.6 years. During follow-up, 954 incident AF cases were identified; 9.5% in smokers vs. 7.8% in non-smokers; p