Ambient fine particulate matter exposure and myocardial ischemia in the Environmental Epidemiology of Arrhythmogenesis in the Women's Health Initiative (EEAWHI) study

Background: Ambient particulate matter (PM) air pollution is associated with coronary heart disease, but the pathways underlying the association remain to be elucidated. Methods: We studied the association between PM and ischemia among 57,908 Women's Health Initiative clinical trial participants from 1999-2003. We used the Minnesota Code criteria to identify ST-segment and T-wave abnormalities, and estimated T amplitude (microvolt) from resting, standard 12-lead electrocardiogram (ECG). We used U.S. Environmental Protection Agency's monitor data to estimate concentrations of PM < 2.5 μm (PM_2.5) at geocoded participant addresses over 6 days before the ECGs (lag0 through lag5). We excluded 2,379 women with ECG QRS duration ≥ 120 msec. Results: Overall, 6% of the remaining 55,529 women (52-90 years of age; 83% non-Hispanic white) had ST abnormalities and 16% had T abnormalities. Lead-specific T amplitude was normally distributed (range of means from -14 to 349 μV). PM_2.5 (mean ± SD) averaged over lag_0-2 was 14 ± 7 μg/m³. In logistic and linear regression models adjusted for demographic, clinical, temporal, and climatic factors, a 10-μg/m³ increase in lag_0-2 PM_2.5 was associated with a 4% [95% confidence interval (CI), -3%, to 10%] increase in the odds of ST abnormality and a 5% (95% CI, 0% to 9%) increase in the odds of T abnormality. We observed corresponding decreases in T amplitude in all exam sites and leads except lead V1, reaching a minimum of -2 μV (95% CI, -5 to 0 μV) in lead V3. Conclusions: Short-term PM_2.5 exposure is associated with ECG evidence of myocardial ischemia among postmenopausal women. The principal manifestations include subclinical but potentially arrhythmogenic ST-T abnormalities and decreases in T amplitude.