AIMS We aimed to investigate whether long-term exposure to particulate matter with an aerodynamic diameter <2.5 μm (PM2.5) in the ambient air is related to the development or growth of coronary plaques.

METHODS AND RESULTS This study involved 364 residents of Seoul, Korea, who underwent serial coronary computed tomographic angiography (CCTA) at an interval of ≥2 years. Each participant's average concentration of residential PM2.5 between the two CCTAs was calculated. Primary endpoint was the development of high-risk plaque (HRP), defined as a plaque with low attenuation, spotty calcium, and positive remodelling. Secondary endpoints were the volume increase of total plaque and its component volume. Among those without HRP at baseline (n = 341), 20 patients developed HRP at follow-up CCTA, the residential PM2.5 concentration of which was significantly higher than those without HRP at follow-up (25.8 ± 2.0 vs. 25.0 ± 1.7 μg/m3 for patients with newly developed HRP vs. patients without HRP at follow-up; P = 0.047). An increase in PM2.5 concentration was associated with increased incidence of HRP at follow-up [adjusted hazard ratio (aHR) 1.62, 95% confidence interval (CI) 1.22-2.15, P < 0.001]. In a secondary analysis, the PM2.5 concentration was associated with an increased risk of the formation of either fibrofatty or necrotic core component in newly developed plaques (aHR 1.41, 95% CI 1.23-1.61, P < 0.001), and with a higher risk of total plaque volume progression in the pre-existing plaques (aHR 1.14, 95% CI 1.05-1.23, P = 0.002).

CONCLUSION Exposure to higher concentration of PM2.5 in the ambient air is significantly associated with the development of high-risk coronary plaques.