Pathology and Pathophysiology of Coronary Atherosclerotic Plaques

Abstract

The human heart is covered by two different fat depots, the epicardial fat, located between the myocardium and visceral pericardium, and the pericardial fat, situated outside the visceral pericardium and on the external surface of the parietal pericardium. Epicardial and pericardial fat are embryologically, anatomically, functionally and clinically different. Epicardial adipose tissue is a peculiar visceral fat depot. It has anatomical and functional contiguity to the myocardium and coronary arteries and directly reflects the intra-myocardial fat content. Under physiological conditions epicardial adipose tissue displays biochemical, mechanical and thermogenic cardio-protective properties. Under pathological circumstances, epicardial fat could locally affect the heart and the coronary arteries through vasocrine or paracrine secretion of pro-inflammatory cytokines. What could influence this equilibrium between harmful or protective effects is still unclear. Improved local vascularization, weight loss and targeted pharmaceutical interventions might allow the epicardial fat to resume its physiological role. Epicardial fat can be accurately measured with imaging techniques, as well as echocardiography, multidetector computer tomography or cardiac magnetic resonance imaging. Regardless of how it is measured, epicardial fat has been associated with coronary artery diseases, subclinical atherosclerosis, insulin resistance, metabolic syndrome and abnormal heart morphology. Its clinical measurement is a good and reproducible marker of visceral and myocardial adiposity and a potential predictor of cardio- metabolic risk.