Association between long-term exposure to air pollution and cardio-metabolic phenotypes – A MRI-data based analysis

Abstract

Background and Aim: Long-term exposure to ambient air pollution is supposed to affect both the cardiovascular system and adipose tissue (AT) metabolism. However, its role in the early subclinical stages of development before manifestation of cardiometabolic disease is unclear. Thus, we aimed to investigate the impact of long-term exposure to air pollution on cardiometabolic phenotypes derived from magnetic resonance imaging (MRI). Methods: Phenotypes of left (LV) and right cardiac ventricle, whole body AT, and organ AT were obtained by whole-body MRI in 400 participants of the population-based KORA cohort. Land-use regression models were used to estimate residential long-term exposures to several air pollutants, including particulate matter (PM) with different diameters and nitrogen oxides (e.g. NO₂). Associations between exposures and MRI phenotypes were modeled using confounder-adjusted linear regression. Additionally, we performed several stratified analyses, e.g. for diabetes status, hypertension, or age group. Results: Participants’ mean age was 56±9 years, 42% were female. Increasing levels of several air pollutants were associated with decreased LV wall thickness; a 6.0μg/m³ IQR (interquartile range) increase in NO₂ was significantly associated with a -1.89% decrease (95% confidence interval [95%-CI]: -3.70;-0.09) in mean global LV wall thickness. We also found significant associations between various air pollutants and increased cardiac AT. A 2.1μg/m³ IQR increase in PM₁₀ was associated with an 8.83% [95%-CI: 1.19;16.49] increase in mean total epi- and pericardial AT. Similar effects were seen for mean diastolic (8.53% [95%-CI: 0.84;16.23]) and systolic (8.57% [95% CI: 0.10;16.17]) pericardial AT, respectively. We saw a similar trend for liver and renal AT. Associations with whole-body AT were only detected in participants with diabetes in the stratified analysis. Conclusions: Our results indicate that long-term exposure to air pollution is associated with subclinical cardiometabolic disease states, particularly in metabolically vulnerable subgroups. Keywords: cardiometabolic phenotypes, ambient air pollution, magnetic resonance imaging.