Air Pollution and Coronary Artery Calcification
What is the association between long-term exposure to ambient air population and progression of coronary artery calcium (CAC) and common carotid artery intima-media thickness (IMT)?
MESA Air (Multi-Ethnic Study of Atherosclerosis and Air Pollution) was a 10-year prospective cohort study. The authors repeatedly measured CAC by computed tomography in 6,795 participants ages 45-84 years. Common carotid artery IMT was measured by ultrasound in all participants at baseline and in 2010-2012 for 3,459 participants. Air pollution concentrations included particulate matter (PM) less than 2.5 microns in diameter (PM2.5/m3), nitrogen oxides, and black carbon. The primary aim of this study was to examine associations between progression of CAC and mean carotid artery IMT and long-term exposure to ambient air pollutant concentrations between examinations and within six metropolitan areas.
For each 5 microgram PM2.5/m3 increase, coronary calcium progressed by 4.1 Agatston units per year (95% confidence interval, 4-6.8) and for each 40 ppb nitrogen oxide, coronary calcium progressed by 4.8 Agatston units per year (0.9-8.7). Pollutant exposures were not associated with carotid artery IMT.
Ambient concentrations of PM and nitrogen oxide were associated with CAC progression. Air pollution was not associated with carotid IMT.
This is an important study that supports the association between air pollution and progression of subclinical atherosclerosis. The association between PM and CAC progression was stronger in those who were hypertensive and >65 years. As the authors opine, “This study supports the case for global efforts of pollution reduction in prevention of cardiovascular diseases.”
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