Air pollution exposure and coronary artery calcification. The Mexican GEA study.

Abstract

Background: Coronary artery calcium (CAC) is a very strong risk marker of future ischemic vascular events and a better predictor of CVD than intima media thickness, C-reactive protein or the Framingham Risk Score. WHO has identified air pollution as the world's largest single environmental-health risk, and 80% of deaths related to outdoor air pollution result from ischemic heart disease and stroke, however studies about the association of CAC and air pollution are scarce, especially in Mexico City. Therefore, we evaluated whether environment PM2.5 is associated with CAC in an adult population from Mexico City Metropolitan Area.Methods: In 1690 participants (24 to 81 yo) from the Mexican GEA cohort of Mexico City Metropolitan Area, PM2.5 exposure were calculated (from 1-5y before the visit day) using inverse distance weighted of data from air quality monitors. CAC was measured by computed tomography in all participants of the GEA study. Three different groups were analyzed: 975 participants with CAC=0, 377 with subclinical atherosclerosis (median 26.4 Agatston units, IQR 88.5) and 338 participants with coronary artery disease (median 84.7, IQR 425.4). The association of CAC and PM2.5 exposure was evaluated by Tobit regression model adjusted for confounding factors (BMI, sex, age, education, smoking, diabetes, CHDL, CLDL, SBP and group).Results: A 10ug/m3 increase of PM2.5 exposure at year 4 (Β=0.27, 95% CI 0.08, 0.46) was positively associated with increased CAC. Sensitivity analysis, excluding participants with coronary artery disease, confirms that a 10ug/m3 increase of PM2.5 exposure at year 4 (Β=0.26, 95% CI 0.01, 0.50) was positively associated with increased CAC.Conclusion: Our preliminary results indicate that an increased in PM2.5 levels are associated with CAC in adults from Mexico City, suggesting an urgent need to modify the air-quality guidelines and regulatory limits to reduce the impact on cardiovascular risk in adults from Mexico City.