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Exposure to Traffic and Left Ventricular Mass and Function

The Multi-Ethnic Study of Atherosclerosis

¹ Department of Environmental and Occupational Health Sciences, ² Department of Medicine, and ³ Department of Biostatistics, University of Washington, Seattle, Washington; ⁴ Departments of Medicine and Epidemiology, Columbia University, New York, New York; ⁵ Departments of Radiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and ⁶ Department of Epidemiology, University of Michigan, Ann Arbor, Michigan

Correspondence and requests for reprints should be addressed to Victor C. Van Hee, M.D., M.P.H., Department of Environmental and Occupational Health Sciences, University of Washington, Box 359739, Seattle, WA 98104. E-mail: vvanhee{at}u.washington.edu

Rationale: Ambient air pollution has been associated with heart failure morbidity and mortality. The mechanisms responsible for these associations are unknown but may include the effects of traffic-related pollutants on vascular or autonomic function.

Objectives: We assessed the cross-sectional relation between long-term air pollution, traffic exposures, and important end-organ measures of alterations in cardiac function—left ventricular mass index (LVMI) and ejection fraction—in the Multi-Ethnic Study of Atherosclerosis, a multicenter study of adults without previous clinical cardiovascular disease.

Methods: A total of 3,827 eligible participants (aged 45–84 yr) underwent cardiac magnetic resonance imaging between 2000 and 2002. We estimated air pollution exposures using residential proximity to major roadways and interpolated concentrations of fine particulate matter (less than 2.5 microns in diameter). We examined adjusted associations between these exposures and left ventricular mass and function.

Measurements and Main Results: Relative to participants living more than 150 m from a major roadway, participants living within 50 m of a major roadway showed an adjusted 1.4 g/m² (95% CI, 0.3–2.5) higher LVMI, a difference in mass corresponding to a 5.6 mm Hg greater systolic blood pressure. Ejection fraction was not associated with proximity to major roadways. Limited variability in estimates of fine particulate matter was observed within cities, and no associations with particulate matter were found for either outcome after adjustment for center.

Conclusions: Living in close proximity to major roadways is associated with higher LVMI, suggesting chronic vascular end-organ damage from a traffic-related environmental exposure. Air pollutants or another component of roadway proximity, such as noise, could be responsible.

Key Words: epidemiology • particulate matter • hypertrophy • heart failure • magnetic resonance imaging

AT A GLANCE COMMENTARY Scientific Knowledge on the Subject Although air pollution has been associated with cardiovascular disease morbidity and mortality, including heart failure hospitalizations, a relationship between air pollution and left ventricular mass or function has not previously been observed. What This Study Adds to the Field Traffic exposure, as measured by very close (less than 50 m) home proximity to major roadways, is associated with higher left ventricular mass in adults, corresponding to the effect of a 6 mm Hg increase in systolic blood pressure. Although air pollutants are the likely cause, other traffic-derived environmental conditions should be considered.