Association of Fine Particulate Matter and Risk of Stroke in Patients With Atrial Fibrillation.

This cohort study assesses the association between annual, residential-level exposure to fine particulate matter and ischemic stroke in individuals with atrial fibrillation. Question What is the association between fine particulate matter measuring 2.5 mu m or less (PM2.5) air pollution and ischemic stroke in individuals with prevalent atrial fibrillation (AF)? Findings This cohort study including 31414 individuals with AF found an association between PM(2.5)and prospective ischemic stroke risk in longitudinal, residential-level assessments in a large health care system situated in a region with high industrial activity. In multivariable-adjusted analyses that included relevant covariates and neighborhood-level income and educational level, individuals in the highest quartile of PM(2.5)exposure had a 1.2-fold higher risk of stroke compared with the lowest quartile. Meaning The association between residential-level pollution and stroke risk in the presence of AF appears to be an additional public health toll of pollution and suggests that stroke risk assessment in individuals with AF take into account the contributions of environmental exposures. Importance Air pollution is associated with cardiovascular outcomes. Specifically, fine particulate matter measuring 2.5 mu m or less (PM2.5) is associated with thrombosis, stroke, and myocardial infarction. Few studies have examined particulate matter and stroke risk in individuals with atrial fibrillation (AF). Objective To assess the association of residential-level pollution exposure in 1 year and ischemic stroke in individuals with AF. Design, Setting, and Participants This cohort study included 31414 individuals with AF from a large regional health care system in an area with historically high industrial pollution. All participants had valid residential addresses for geocoding and ascertainment of neighborhood-level income and educational level. Participants were studied from January 1, 2007, through September 30, 2015, with prospective follow-up through December 1, 2017. Data analysis was performed from March 14, 2018, to October 9, 2019. Exposures Exposure to PM(2.5)ascertained using geocoding of addresses and fine-scale air pollution exposure surfaces derived from a spatial saturation monitoring campaign and land-use regression modeling. Exposure to PM(2.5)was estimated annually across the study period at the residence level. Main Outcomes and Measures Multivariable-adjusted stroke risk by quartile of residence-level and annual PM(2.5)exposure. Results The cohort included 31414 individuals (15 813 [50.3%] female; mean [SD] age, 74.4 [13.5] years), with a median follow-up of 3.5 years (interquartile range, 1.6-5.8 years). The mean (SD) annual PM(2.5)exposure was 10.6 (0.7) mu g/m(3). A 1-SD increase in PM(2.5)was associated with a greater risk of stroke after both adjustment for demographic and clinical variables (hazard ratio [HR], 1.08; 95% CI, 1.03-1.14) and multivariable adjustment that included neighborhood-level income and educational level (HR, 1.07; 95% CI, 1.00-1.14). The highest quartile of PM(2.5)exposure had an increased risk of stroke relative to the first quartile (HR, 1.36; 95% CI, 1.18-1.58). After adjustment for clinical covariates, income, and educational level, risk of stroke remained greater for the highest quartile of exposure relative to the first quartile (HR, 1.21; 95% CI, 1.01-1.45). Conclusions and Relevance This large cohort study of individuals with AF identified associations between PM(2.5)and risk of ischemic stroke. The results suggest an association between fine particulate air pollution and cardiovascular disease and outcomes.