Correlation of epicardial fat quantification with severity of coronary artery disease: A study in Indian population

Abstract

Objective: We studied the correlation of quantified epicardial fat with severity of coronary artery disease in patients [suspected cases of coronary artery disease (CAD)] referred for computed tomography (CT) coronary angiography and established cutoffs for epicardial fat volume (EFV) for the presence of CAD and obstructive CAD.

Methods: A prospective cum retrospective cross-sectional observational study was carried out on 950 Indian subjects (suspected cases of CAD) who were referred for coronary CT in the year 2013-2016. EFV was quantified using semiautomatic technique on multidetector coronary CT angiography. The presence of atherosclerotic plaques and degree of stenosis was assessed on coronary CT angiography scans. The correlation between quantified EFV and degree of stenosis was assessed. Multivariate analysis was also performed.

Results: A higher quantity of epicardial fat is found in patients with increasing severity of coronary artery stenosis. The EFV cutoff for the presence of CAD and obstructive CAD are 49.75 and 67.69 mL with area under the curve, sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of 0.68, 81%, 45.9%,58.24%, 72.2%, and 62.84% and 0.709, 64.9%, 66.4%, 35.84%, 86.55%, and 66%, respectively. EFV correlates with age, weight, and body mass index (BMI). Multivariate analysis revealed EFV to be an independent risk factor for the presence of CAD.

Conclusions: Higher quantities of EFV are found in patients with greater degree of coronary artery stenosis. EFV correlates with age, weight, and BMI. EFV is an independent risk factor for CAD.

Keywords: Epicardial fat; Epicardial fat quantification; Epicardial fat volume; Regional thoracic fat depots.

Fig. 1

Contrast-enhanced axial coronary CT angiography images depicting the regional thoracic fat depots: epicardial and paracardial fat. (a) Epicardial fat (green trace) is the adipose tissue located between the myocardium and the visceral pericardium. (b) Paracardial fat (pink trace) is the fatty tissue situated in the mediastinum outside the parietal pericardium. Pericardial fat is the sum of epicardial and paracardial fat. CT, computed tomography.

Fig. 2

The methodology of quantification of epicardial fat volume on MDCT using semiautomated technique. Step 1: reconstruction of a batch film using end-systolic phase of CT coronary angiography (slice thickness: 3 mm, reconstruction increment: 1.5 mm). Step 2: manual trace of the pericardial contour in the reconstructed slices. Step 3: application of fat attenuation threshold (−250 to −50 H U.). Step 4: highlighted epicardial fat. Step 5: epicardial fat quantified. CT, computed tomography.