Long-Term Exposures to Air Pollution and the Risk of Atrial Fibrillation

Background: Atrial fibrillation (AF) is the most common heart rhythm disorder and is associated with substantial morbidity and mortality. Established risk factors explain only 50%-60% of AF cases, therefore identification of novel population-level risk factors is vital. Short-term exposures to air pollution have been associated with AF triggering, however, only a single study has examined associations between long-term exposures and AF incidence.Methods: We used information from the Women’s Health Initiative to explore the association between annual average exposures to PM10, PM2.5, NO2, SO2, O3, and risk of incident AF. Exposures were estimated at each address from nationwide spatiotemporal models and distance to road was calculated. Cases of AF were identified through linkage with Centers for Medicare & Medicaid Services data. Time-varying Cox proportional-hazards regression models were adjusted for known AF risk factors and splines were used to assess deviations of the exposure-response functions from linearity.Results: Among 78,060 eligible participants, there were 15,288 incident cases of AF. Only associations with PM2.5 were linear. Increasing exposures to PM2.5, PM10, and SO2 were not associated with higher risk of AF. NO2, and living closer to a roadway, however, were associated with higher risks of AF. For example, women with annual average NO2 exposures in the top quartile (17.1-48.4 ppb) had an HR=1.23 (95% CI: 1.17, 1.29) compared to those in the bottom quartile (0.4-8.0 ppb) and women living furthest from the largest roads (>5,070m) had an HR=0.96 (95%CI:0.91, 0.99) compared to those living within 1,007m. Findings were similar in sensitivity analyses additionally adjusted for neighborhood SES. (N=70,962; NO2 top quartile HR=1.24 (95% CI: 1.17, 1.31); >5,070m HR=0.97 (95%CI: 0.92, 1.01)).Conclusions: Among this nationwide study of postmenopausal women, increases in traffic-related air pollution exposures were associated with an increased risk of AF.