Cardiac computed tomography-derived epicardial fat volume and attenuation independently distinguish patients with and without myocardial infarction

BACKGROUND AND OBJECTIVE Epicardial adipose tissue (EAT) volume is associated with coronary plaque burden and adverse events. We aimed to determine, whether CT-derived EAT attenuation in addition to EAT volume distinguishes patients with and without myocardial infarction. METHODS AND RESULTS In 94 patients with confirmed or suspected coronary artery disease (aged 66.9±14.7years, 61%male) undergoing cardiac CT imaging as part of clinical workup, EAT volume was retrospectively quantified from non-contrast cardiac CT by delineation of the pericardium in axial images. Mean attenuation of all pixels from EAT volume was calculated. Patients with type-I myocardial infarction (n = 28) had higher EAT volume (132.9 ± 111.9ml vs. 109.7 ± 94.6ml, p = 0.07) and CT-attenuation (-86.8 ± 5.8HU vs. -89.0 ± 3.7HU, p = 0.03) than patients without type-I myocardial infarction, while EAT volume and attenuation were only modestly inversely correlated (r = -0.24, p = 0.02). EAT volume increased per standard deviation of age (18.2 [6.2-30.2] ml, p = 0.003), BMI (29.3 [18.4-40.2] ml, p<0.0001), and with presence of diabetes (44.5 [16.7-72.3] ml, p = 0.0002), while attenuation was higher in patients with lipid-lowering therapy (2.34 [0.08-4.61] HU, p = 0.04). In a model containing volume and attenuation, both measures of EAT were independently associated with the occurrence of type-I myocardial infarction (OR [95% CI]: 1.79 [1.10-2.94], p = 0.02 for volume, 2.04 [1.18-3.53], p = 0.01 for attenuation). Effect sizes remained stable for EAT attenuation after adjustment for risk factors (1.44 [0.77-2.68], p = 0.26 for volume; 1.93 [1.11-3.39], p = 0.02 for attenuation). CONCLUSION CT-derived EAT attenuation, in addition to volume, distinguishes patients with vs. without myocardial infarction and is increased in patients with lipid-lowering therapy. Our results suggest that assessment of EAT attenuation could render complementary information to EAT volume regarding coronary risk burden.