PM_2.5 concentration in the ambient air is a risk factor for the development of high-risk coronary plaques

Aims: We aimed to investigate whether long-term exposure to particulate matter with an aerodynamic diameter <2.5 μm (PM_2.5) 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 PM_2.5 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 PM_2.5 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 PM_2.5 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 PM_2.5 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 PM_2.5 in the ambient air is significantly associated with the development of high-risk coronary plaques.