Epicardial adipose tissue (EAT) is increased in subjects with atrial fibrillation (AF). Likewise, EAT is associated with left atrial (LA) size, as itself is a strong predictor of AF. We aimed to determine the association of EAT and LA size as computed tomography (CT)-derived measures with prevalent and incident AF and investigated whether both measures independently predict AF. Participants from the Heinz Nixdorf Recall study without known cardiovascular disease were included. At baseline, EAT, defined as fat volume inside the pericardial sac, and LA size, defined as an axial area at the level of the mitral valve, were quantified from non-contrast enhanced cardiac CT. AF was determined from electrocardiogram at baseline and also at 5-year follow-up examination. Overall, 3467 participants (age: 58.9 ± 7.6 years, 47% male) were included. Ninety-six subjects had AF (46 prevalent and 50 incident). A 1-standard deviation (SD) change of EAT was associated with nearly two-fold increased prevalence of AF in univariate analysis, which persisted after adjustment for AF risk factors [odds ratio (OR) (95% confidence interval, 95% CI): 1.38 (1.11–1.72), P = 0.003]. Ancillary adjusting for LA reduced the effect [1.26 (0.996–1.60), P = 0.054]. For incident AF, no relevant effect was observed for EAT when adjusting for risk factors [1.19 (0.88–1.61), P = 0.26]. In contrast, a 1-SD chance of LA was strongly associated with AF independently of EAT and risk factors [2.70 (2.22–2.20), P < 0.0001]. LA but not EAT as non-contrast CT-derived measures improved the prediction of AF over risk factors (receiver operating characteristics: 0.810–0.845, P = 0.025). LA size from non-contrast CT is strongly associated with prevalent and incident AF and ultimately diminishes the link of EAT with AF.

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. 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). 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.