Epicardial and Perivascular Adipose Tissues and Their Influence on Cardiovascular Disease: Basic Mechanisms and Clinical Associations

I t is well established that the cardiovascular (CV) risk of obesity is more strongly associated with visceral rather than subcutaneous adiposity. Anthropometric variables that account for visceral adiposity, such as body mass index (BMI) and waist circumference (WC), have limited sensitivity and specificity. Furthermore, there is increasing recognition of “normal weight obese” persons (ie, those with increased visceral adipose but normal WC) who are prone to the same risk of the metabolic syndrome. These patients are detected only through abdominal computed tomography (CT) or magnetic resonance imaging (MRI). Rapid advancements in noninvasive cardiac imaging techniques have fostered interest in the imaging of perivascular and epicardial fat as proxy measures of visceral adiposity and, hence, more sensitive and specific indicators of cardiometabolic risk. The idea that these fat depots may not only be representative of abdominal visceral adipose tissue (VAT) but perhaps independently causal of CV disease (CVD) is an attractive one that is rapidly gaining traction. The potential roles of perivascular and epicardial fat in obesity-associated CVD are best understood in the context of the pathophysiology of obesity-induced insulin resistance.