Abstract 10114: Secondhand Tobacco Smoke Exposure, Urine Cotinine, and Risk of Incident Atrial Fibrillation: The Multi-Ethnic Study of Atherosclerosis

Abstract

Importance: Secondhand tobacco smoke (SHS) exposure may reduce heart rate variability and has been associated with atrial fibrillation (AF), but the association of SHS with AF has not been confirmed using objective measures for both SHS and incident AF events. Objectives: To investigate the association of self-reported and objective SHS exposure amounts with incident AF. Design: Cohort study. Setting: The Multi-Ethnic Study of Atherosclerosis (MESA) included 6 USA sites. We used follow-up data from the first visit (2000-2002) through 2015. Participants: The study sample consisted of 5,730 participants, aged 45-84 years and free of known AF and other cardiovascular diseases at baseline, who self-reported SHS exposure time in hours per week. We also selected a cohort subset of 3,237 current non-smoking participants who received spot urine cotinine measurements at baseline (2000-2002). Exposures: Self-reported SHS exposure time (whole cohort) and urine cotinine levels (cohort subset). Main Outcomes and Measures: AF events were identified using Medicare claims, hospital records and electrocardiographic findings. A multivariable Cox proportional hazards regression model was used with simultaneous adjustment for demographic factors, educational level, health insurance status, active smoking status, tobacco pack-years, traditional cardiovascular risk factors, depressive symptoms and medications. Results: During a median follow-up of 14.0 years, 856 and 452 AF events were identified in the overall and the cohort subset, respectively. No association of SHS exposure time or urine cotinine with incident AF was found. However, a higher AF risk with greater urine cotinine (8.53-442.0 ng/mL) compared with lower urine cotinine (≤7.07 ng/mL) was observed in never smokers [hazard ratios (HR): 1.60 (95% confidence intervals (CI): 1.16, 2.19)], but not in former smokers [HR: 0.88 (95% CI: 0.63, 1.23)] (p-value for multiplicative interaction: 0.009 and for additive interaction: 0.017, respectively). Conclusions and Relevance: Objectively measured greater SHS exposure expressed by urine cotinine might be associated with 1.6-fold higher risk of incident AF in never smokers.