Abstract P138: The Association of Long-Term Air Pollution Exposure With Left Atrial Structure and Function in the Multi-Ethnic Study of Atherosclerosis

Abstract

Air pollution exposure is an important risk factor for cardiovascular morbidity and mortality. Acute exposure is associated with episodes of atrial fibrillation (AF), and long-term exposure may influence ventricular mass and volume. However, little is understood about the relationship between long-term pollution exposure and atrial structure and function, which may influence risk of AF and heart failure. We sought to determine the association of long-term exposure to oxides of nitrogen (NO X ), particulate matter smaller than 2.5 micrometers (PM 2.5 ), and ozone (O 3 ) with left atrial structure (LA) and function, as measured by LA volume, emptying fraction, and peak longitudinal strain. In the Multi-Ethnic Study of Atherosclerosis (MESA), a longitudinal study of 6,814 participants in six United States communities, we used estimated 5-year average exposure to PM 2.5 , NO X , and O 3 prior to outcome measurement from validated hierarchical spatio-temporal models developed from extensive monitoring of MESA participants. Left atrial measures were calculated from cardiac magnetic resonance imaging occurring between 2010 and 2012. Linear regression was used, adjusting for MESA study site and potential confounding characteristics. In 2,250 MESA participants, 5-year average exposure to PM 2.5 , NO X , and O 3 varied greatly by study site and was not associated with LA volume, emptying fraction, or peak longitudinal strain. Results were particularly sensitive to adjustment for study site, suggesting that there was substantial unmeasured confounding by US city/region. Using recently developed study-specific exposure estimation and highly accurate imaging, we did not find evidence to suggest an association between long-term exposure to several common pollutants and measures of left atrial structure and function. Additional analyses in areas of higher pollution may be useful in determining whether associations are consistent across exposure levels.