VICTOR VAN HEE
Traffic-Related Air Pollution and Left Ventricular Mass and Function:
The Multi-Ethnic Study of Atherosclerosis
Occupational and Environmental Medicine, MPH
Preceptor: Joel Kaufman, MD, MPH
Introduction: Long-term exposure to particulate matter air pollution has been associated with cardiovascular morbidity and mortality in several large epidemiologic studies, but the mechanisms remain unclear. One means by which particulate matter may exert its negative cardiovascular effects is through changes in cardiac structure and function. Increases in left ventricular mass index (LVMI) and decreases in ejection fraction (EF) represent deleterious changes in cardiac structure and function that are associated with congestive heart failure (CHF). We hypothesized that proximity to major roadways, a marker of particulate matter exposure, would be associated with increases in LVMI and decreases in EF.
Methods: The residential addresses of 4,478 participants without cardiovascular disease (CVD) in the Multi-Ethnic Study of Atherosclerosis were geocoded. Exposure to traffic-generated pollutants was estimated by measuring the distance from each participant's home to the nearest major roadway, as defined by census feature class codes (CFCC) A1*-A3*. LVMI and EF were measured by cardiac MRI, a highly sensitive technique. We performed multiple linear regression to determine the adjusted cross-sectional relationship between several measures of proximity to major roadways (50, 100, and 150 meter thresholds) and measures of cardiac structure and function (LVMI and EF), adjusted for gender, age, race, blood pressure, fasting glucose, education, income, smoking, second-hand smoke exposure, weekly alcohol intake, LDL cholesterol, anti-hypertensive, lipid-lowering, and diabetes therapy, and metropolitan area. In an exploratory analysis, we examined for the presence of effect modification by demographic covariates, risk factors, and disease status.
Results: Among MESA participants with at least 5 years residence at their home address and compared to participants living >150 meters from a major roadway, living within 50 meters of a major roadway was associated with a 3.37 gram (95% CI: 0.33, 6.41) increase in LVMI. Living between 50 and 150 meters was associated with no significant difference in LVMI compared to participants living >150 meters from a major roadway. Although there was no statistically significant evidence of effect modification, larger adjusted point estimates of the 50 meter association were observed for Hispanics, African Americans, current smokers, persons with diabetes, and males. EF was not associated with proximity to major roadways.
Conclusions: Close proximity to major roadways is associated with increased LVMI, in a manner consistent with an effect of traffic-related air pollution. This association may be stronger in certain sensitive subpopulations. EF may be a less sensitive indicator than LVMI, especially in this cohort of participants without CVD.
