Background: High-risk plaques (HRP) detected on coronary computed tomography angiography (CTA) confer an increased risk of acute coronary syndrome (ACS). Pericoronary adipose tissue attenuation (PCAT) is a novel biomarker of coronary inflammation. This study aimed to evaluate the association of PCAT with HRP and subsequent ACS development in patients with stable coronary artery disease (CAD). Methods: Patients with stable CAD who underwent coronary CTA from 2011 to 2016 and had available outcome data were included. We studied 41 patients with HRP propensity matched to 41 controls without HRP (60 ± 10 years, 67% males). PCAT was assessed using semi-automated software on a per-patient basis in the proximal right coronary artery (PCAT_RCA) and a per-lesion basis (PCAT_Lesion) around HRP in cases and the highest-grade stenosis lesions in controls. Results: PCAT_RCA and PCAT_Lesion were higher in HRP patients than controls (PCAT_RCA: −80.7 ± 6.50 HU vs. −84.2 ± 8.09 HU, p = 0.03; PCAT_Lesion: −79.6 ± 7.86 HU vs. −84.2 ± 10.3 HU, p = 0.04), and were also higher in men (PCAT_RCA: −80.5 ± 7.03 HU vs. −86.1 ± 7.08 HU, p < 0.001; PCAT_Lesion: −79.6 ± 9.06 HU vs. −85.2 ± 7.96 HU, p = 0.02). Median time to ACS was 1.9 years, within a median follow-up of 5.3 years. PCAT_RCA alone was higher in HRP patients who subsequently presented with ACS (−76.8 ± 5.69 HU vs. −82.0 ± 6.32 HU, p = 0.03). In time-dependent analysis, ACS was associated with HRP and PCAT_RCA. Conclusions: PCAT attenuation is increased in stable CAD patients with HRP and is associated with subsequent ACS development. Further investigation is required to determine the clinical implications of these findings.

A large body of evidence arising from recent randomized clinical trials demonstrate the association of vascular inflammatory mediators with coronary artery disease (CAD). Vascular inflammation localized in the coronary arteries leads to an increased risk of CAD-related events, and produces unique biological alterations to local cardiac adipose tissue depots. Coronary computed tomography angiography (CTA) provides a means of mapping inflammatory changes to both epicardial adipose tissue (EAT) and pericoronary adipose tissue (PCAT) as independent markers of coronary risk. Radiodensity or attenuation of PCAT on coronary CTA, notably, provides indirect quantification of coronary inflammation and is emerging as a promising non-invasive imaging implement. An increasing number of observational studies have shown robust associations between PCAT attenuation and major coronary events, including acute coronary syndrome, and ‘vulnerable’ atherosclerotic plaque phenotypes that are associated with an increased risk of the said events. This review outlines the biological characteristics of both EAT and PCAT and provides an overview of the current literature on PCAT attenuation as a surrogate marker of coronary inflammation.