70. Epicardial fat quality effect on subclinical atherosclerosis

Abstract

Epicardial fat quality measured as Hounsfield Unit (HU) by computed tomography has significant impact on atherosclerosis. Excessive epicardial adipose tissue (EAT) is considered a risk factor for coronary artery disease (CAD). There are limited data, however, about the quality of epicardial fat as a CAD risk factor. We investigated the relation between EAT volume and quality and subclinical CAD defined by positive coronary artery calcification (CAC) using computed tomography (CT). We reviewed 609 CT scans to assess the EAT volume, which was measured by manually tracing the parietal pericardial sac on axial images. Fat density was recorded in mean Hounsfield units (HU). Coronary calcium scores were measured using the Agatston method. The patients’ mean age was 50 ± 11 years, and 398 (65.4%) were men. The mean EAT volume was 65 ± 27 cm 3 , and it had a density of 87.0 ± 3.4 HU. Calcium was present in 135 (22%) of the patients: 97 (16% of the total) were men and 38 (6%) were women. There was no difference between the sexes in regard to EAT volume (66 ± 27 vs. 63 ± 26, p = 0.34) or density (87.4 ± 3.2 vs. 87.0 ± 3.6, p = 0.28). Obese patients (body mass index ⩾30 kg/m 2 had significantly higher EAT volumes than nonobese patients (73 ± 30 vs. 61 ± 29, p = 0.011), but no difference was seen in CAC (33 ± 97 vs. 27 ± 103, p = 0.34) or fat density (87.7 ± 4.0 vs. 88.0 ± 2.7, p = 0.48). Univariate regression analyses showed that higher fat attenuation (HU) was associated with a lower coronary atherosclerosis hazard ratio (HR) (0.871, 95% confidence interval [CI] 0.790–0.948, p p = 0.0001). The quality of EAT, measured as HU on CT, is a strong predictor of subclinical CAD as defined by coronary artery calcifications, with a higher HU associated with a lower incidence of atherosclerosis.