Abstract 059: Long-term Exposure to Oxides of Nitrogen and Left Ventricular Mass in the Multi-Ethnic Study of Atherosclerosis and Air Pollution
Objective: To determine whether long-term exposure to oxides of nitrogen (NOx) is associated with left ventricular mass index (LVMI) in adults without known cardiovascular disease (CVD).
Background: An association between very close (<50 meter) residential proximity to major roadways and LVMI, an important predictor of heart failure, has been previously described. To date, the relationship between LVMI and NOx, a specific, gaseous traffic related pollutant and more reliable surrogate for traffic-related pollution, has not been examined.
Methods: This study included 4125 participants free of clinical cardiovascular disease in the Multi-Ethnic Study of Atherosclerosis (MESA) who underwent cardiac MRI, cardiac computed tomography (CT), and an extensive air pollution exposure assessment campaign to determine long-term individual residential exposure to NOx. This study used year 2000 average exposure to estimate long term exposure to NOx. LVMI was calculated by indexing cardiac MRI measures of left ventricular mass to body surface area measured at the exam. Agatston score was calculated based on cardiac CT. Multiple linear regression was used to examine the association between long-term exposure to NOx and LVMI, adjusted for multiple potential confounders including study site. To examine whether such relationships may be mediated by atherosclerosis or blood pressure, additional adjustment for Agatston score and blood pressure was performed.
Results: An interquartile range (44 ppb) increase in estimated residential NOx was associated with significantly higher LVMI (1.6 g/m2, 95% CI: 0.1 to 3.1, p=0.03). Such estimates were comparable to prior associations observed for the relationship between close residential proximity to major roadways and LVMI (comparing individuals living 150m away). Additional adjustment for Agatston score and blood pressure had no effect on estimates of association. Stratified analyses suggested interactions with age, with younger individuals demonstrating larger associations than older individuals (p for interaction = 0.05). No significant evidence of effect modification by race, gender, other cardiovascular risk factors, or study site was observed.
Conclusions: This study further supports the observation that long-term exposure to traffic-related air pollution is associated with higher left ventricular mass, and suggests that such associations may be independent of effects on blood pressure or atherosclerotic disease.
- © 2012 by American Heart Association, Inc.