Abstract
BACKGROUND: Increased particulate matter <2.5 μm (PM(2.5)) air pollution is associated with adverse cardiovascular outcomes. However, its impact on patients with prior coronary artery bypass grafting (CABG) is unknown. OBJECTIVES: The purpose of this study was to evaluate the association between major adverse cardiovascular events (MACE) (defined as myocardial infarction, stroke, or cardiovascular death) and air pollution after CABG. METHODS: We linked 26,403 U.S. veterans who underwent CABG (2010-2019) nationally with average annual ambient PM(2.5) estimates using residential address. Over a 5-year median follow-up period, we identified MACE and fit a multivariable Cox proportional hazard model to determine the risk of MACE as per PM(2.5) exposure. We also estimated the absolute potential reduction in PM(2.5) attributable MACE simulating a hypothetical PM(2.5) lowered to the revised World Health Organization standard of 5 μg/m(3). RESULTS: The observed median PM(2.5) exposure was 7.9 μg/m(3) (IQR: 7.0-8.9 μg/m(3); 95% of patients were exposed to PM(2.5) above 5 μg/m(3)). Increased PM(2.5) exposure was associated with a higher 10-year MACE rate (first tertile 38% vs third tertile 45%; P < 0.001). Adjusting for demographic, racial, and clinical characteristics, a 10 μg/m(3) increase in PM(2.5) resulted in 27% relative risk for MACE (HR: 1.27, 95% CI: 1.10-1.46; P < 0.001). Currently, 10% of total MACE is attributable to PM(2.5) exposure. Reducing maximum PM(2.5) to 5 μg/m(3) could result in a 7% absolute reduction in 10-year MACE rates. CONCLUSIONS: In this large nationwide CABG cohort, ambient PM(2.5) air pollution was strongly associated with adverse 10-year cardiovascular outcomes. Reducing levels to World Health Organization-recommended standards would result in a substantial risk reduction at the population level.