Electrocardiographic ST-segment depression and exposure to traffic-related aerosols in elderly subjects with coronary artery disease.
BACKGROUND
Air pollutants have not been associated with ambulatory electrocardiographic evidence of ST-segment depression ≥ 1 mm (probable cardiac ischemia). We previously found that markers of primary (combustion-related) organic aerosols and gases were positively associated with circulating biomarkers of inflammation and ambulatory blood pressure in the present cohort panel study of elderly subjects with coronary artery disease.


OBJECTIVE
We specifically aimed to evaluate whether exposure markers of primary organic aerosols and ultrafine particles were more strongly associated with ST-segment depression of ≥ 1 mm than were secondary organic aerosols or PM2.5 (particulate matter with aerodynamic diameter ≤ 2.5 µm) mass.


METHODS
We evaluated relations of air pollutants to ambulatory electrocardiographic evidence of cardiac ischemia over 10 days in 38 subjects without ST depression on baseline electrocardiographs. Exposures were measured outdoors in retirement communities in the Los Angeles basin, including daily size-fractionated particle mass and hourly markers of primary and secondary organic aerosols and gases. Generalized estimating equations were used to estimate odds of hourly ST-segment depression (≥ 1 mm) from hourly air pollution exposures and to estimate relative rates of daily counts of ST-segment depression from daily average exposures, controlling for potential confounders.


RESULTS
We found significant positive associations of hourly ST-segment depression with markers of combustion-related aerosols and gases averaged 1-hr through 3-4 days, but not secondary (photochemically aged) organic aerosols or ozone. The odds ratio per interquartile increase in 2-day average primary organic carbon (5.2 µg/m3) was 15.4 (95% confidence interval, 3.5-68.2). Daily counts of ST-segment depression were consistently associated with primary combustion markers and 2-day average quasi-ultrafine particles < 0.25 µm.


CONCLUSIONS
Results suggest that exposure to quasi-ultrafine particles and combustion-related pollutants (predominantly from traffic) increase the risk of myocardial ischemia, coherent with our previous findings for systemic inflammation and blood pressure.
Department of Epidemiology, School of Medicine, University of California-Irvine, Irvine, California 92617-7555, USA. rdelfino@uci.edu
Ralph J
RJ
Delfino
Daniel L
DL
Gillen
Thomas
T
Tjoa
Norbert
N
Staimer
Andrea
A
Polidori
Mohammad
M
Arhami
Constantinos
C
Sioutas
John
J
Longhurst
D000336:Aerosols / Q000633:toxicity*; D000368:Aged; D000393:Air Pollutants / Q000633:toxicity*; D003324:Coronary Artery Disease / Q000139:chemically induced* / Q000175:diagnosis*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male
D000336:Aerosols; D000393:Air Pollutants