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 mu m (PM2.5) 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 mu V). PM2.5 (mean +/- SD) averaged over lag(0-2) was 14 7 mu g/m(3). In logistic and linear regression models adjusted for demographic, clinical, temporal, and climatic factors, a 10-mu g/m(3) increase in lag(0-2) PM2.5 was associated with a 4% [95% confidence interval (CI), -3%, to 10%] increase in the odds of ST abnormality and a 5% (95% Cl, 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 VI, reaching a minimum of -2 mu V (95% CI, -5 to 0 mu V) in lead V3. CONCLUSIONS: Short-term PM2.5 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.