In a multivariable model, the single best predictor of outcome was body surface area212 Epicardial adipose tissue is a visceral fat depot of variable volume around the heart that is biochemically active in terms of free fatty acid release and the produc- tion of adipokines.213 In the general population, epicar- dial adipose tissue is known to be associated with meta- bolic syndrome and coronary artery disease risk.210,214 However, preliminary studies have demonstrated low epicardial adipose tissue in patients with HF compared with healthy subjects.215 Furthermore, a recent study found low epicardial adipose tissue in HF to be associ- ated with increased HF mortality, possibly representing a novel component of the obesity paradox in HF.212,216 Taken as a whole, these data suggest that higher body mass, whether fat or lean mass, is associated with im- proved outcomes in the syndrome of HF. The underlying explanatory reasons for this counterintuitive relationship between obesity and improved HF outcomes are not fully understood, although several plausible hypotheses have been put forth.213,214,217,218 Importantly, HF is known to be a catabolic state,215,219 and thus, obesity and increased fat or lean mass likely represent a beneficial greater met- abolic reserve in HF. It is also well recognized that cardiac cachexia or unintentional weight loss is associated with advanced HF state and increased mortality.217,220 In trials that included underweight patients, when patients with obesity were compared with nonobese patients, the det- rimental role of underweight status or cachexia may have confounded the analysis of nonobesity toward an adverse outcome. This is supported by the U-shaped association of BMI and mortality in patients with HF, with increased mortality being observed in patients with a BMI <18.5 . 