Epicardial fat: a non-invasive, non-contrast imaging biomarker for high-risk plaque monitoring in computed tomography

Coronary computed tomography angiography (CCTA) is a viable method for monitoring vulnerable plaque, however, non-contrast calcium scoring (CAS) has a limited utility in this context. The search for novel non-contrast imaging biomarkers able to track high-risk plaque is necessary. To investigate associations between low attenuation plaque (LAP) identified through CCTA and non-contrast CAS, pericardial adipose tissue (PAT), and epicardial adipose tissue (EAT) in patients with non-obstructive coronary atherosclerosis undergoing serial CCTA. We analyzed data from 89 participants (40% women, 60 [7.7] years) of the dietary intervention to stop coronary atherosclerosis in the computed tomography study. CCTA was performed at baseline and repeated at mean follow-up of 66.8 (13.7) weeks. CAS and cardiac fat were measured in non-contrast reconstructions and analyzed in relation to contrast-derived LAP. Mean decrease in LAP burden was 0.23 (1.0) % (P = 0.04), median decrease in PAT volume was 4.2 (-36.9; 8.3) cm³ (P <0.001), median decrease in EAT volume was 2.8 (-12.2; 6.7) cm³ (P = 0.01), and median increase in CAS was 21.2 (1.7; 71.7) Agatston units (P <0.001). Positive correlations were found between changes in LAP burden and both PAT and EAT volumes (r = 0.349, P = 0.001, and r = 0.490, P <0.001, respectively), but not with change in CAS. Multivariable linear regression analysis identified EAT as independent predictor of LAP regression (95% CI, 0.007; 0.032; P = 0.003). Pericardial and epicardial fat volumes and their dynamics are positively associated with LAP burden, while CAS is not. Monitoring EAT volume using non-contrast computed tomography may facilitate the assessment of high-risk plaque progression or regression, overcoming the limitations of CAS.