Editorial Comment: Is increased epicardial fat thickness a marker of the presence of severe coronary artery disease?

Fat is mainly deposited in subcutaneous tissue, but it also accumulates in the abdominal or thoracal region (1). Other major sites of fat accumulation are visceral and cardiac areas; Cardiac fat deposition is now recognized as a new cardiometabolic risk marker, as it is associated with increased insulin resistance, cardiovascular risk factors, as their measurement is practical (2). Fat accumulation in the heart appears in three different types: intracellular, epicardial and pericardial. Intracellular fat is the microscopic lipid accumulation within the cytoplasm of cardiac muscle and can be the result of myocardial ischemia, cell damage or cell death. Epicardial fat is located between the outer wall of the myocardium and the visceral layer of pericardium (3). Pericardial fat exists anterior to the epicardial fat layer and therefore located between visceral and parietal pericardium. Due to the close anatomic relation between myocardium and the epicardial fat, the two tissues share the same microcirculation (4). In previous studies have been reported that epicardial fat is metabolically active and is the source for several adipokines. Potential interactions through paracrine or vasocrine mechanisms between epicardial fat and myocardium are strongly suggested (4).