Epicardial Fat Thickness as a Marker of Coronary Artery Disease Severity and Ischemic Burden: A Prospective Echocardiographic Study

Background/Objectives: Epicardial fat thickness (EFT) is an echocardiographic marker of epicardial adipose tissue that has been linked to coronary atherosclerosis, but its relationship with both coronary artery disease (CAD) severity and myocardial ischemia remains incompletely assessed. This study evaluated the association between EFT, angiographic CAD severity, and stress-induced myocardial ischemia. Methods: In a prospective study, 125 consecutive patients with suspected stable angina underwent transthoracic echocardiography with EFT measurement, dobutamine stress echocardiography, and coronary angiography. EFT was measured at end-systole in the parasternal long-axis view. Significant CAD was defined as ≥50% stenosis in at least one major epicardial coronary artery. Myocardial ischemia was assessed using peak-stress wall motion score index (WMSI). Results: Significant CAD was present in 56% of patients. Mean EFT was significantly higher in patients with significant CAD compared with those without (7.8 ± 2.0 mm vs. 5.5 ± 1.5 mm; p < 0.001). EFT increased progressively with angiographic CAD severity (non-significant CAD: 5.5 ± 1.5 mm; one-vessel disease: 6.5 ± 1.8 mm; two-vessel disease: 7.5 ± 2.0 mm; three-vessel disease: 8.5 ± 1.9 mm; p < 0.001). Patients with EFT > 5 mm had a significantly higher prevalence of significant CAD (68.8% vs. 33.3%; p < 0.001) and were older, with higher body mass index and a greater prevalence of hypertension and obesity. Additionally, peak-stress WMSI was significantly higher in patients with elevated EFT (1.08 ± 0.07 vs. 1.04 ± 0.05; p = 0.005), indicating a greater ischemic burden. Conclusions: EFT is associated with both the anatomical severity of CAD and the extent of stress-induced myocardial ischemia, supporting its potential role in non-invasive risk stratification of patients with suspected CAD.