Relation of echocardiographic epicardial fat thickness and myocardial fat

Epicardial and myocardial fats increase with degree of visceral adiposity and possibly contribute to obesity-associated cardiac changes. Echocardiographic epicardial fat thickness is a new and independent marker of visceral adiposity. The aim of this study was to test whether echocardiographic epicardial fat is related to myocardial fat. Twenty consecutive Caucasian men (body mass index 30.5 +/- 2 kg/m(2), 42 +/- 7 years of age) underwent transthoracic echocardiography for epicardial fat thickness, morphologic and diastolic parameter measurements, hydrogen-1 magnetic resonance spectroscopy for myocardial fat quantification, and magnetic resonance imaging for epicardial fat volume estimation. Hydrogen-1 magnetic resonance spectroscopic myocardial fat content, magnetic resonance imaging of epicardial fat volume, and echocardiographic epicardial fat thickness range varied from 0.5% to 31%, 4.5 to 43 ml, and 3 to 15 mm, respectively. Myocardial fat content showed a statistically significant correlation with echocardiographic epicardial fat thickness (r = 0.79, p <0.01), waist circumference (r = 0.64, p <0.01), low-density lipoprotein cholesterol (r = 0.54, p <0.01), plasma adiponectin levels (r = -0.49, p <0.01), and isovolumic relaxation time (r = 0.59, p <0.01). However, multivariate linear regression analysis showed epicardial fat thickness as the most significant independent correlate of myocardial fat (p <0.001). Although this study is purely correlative and no causative conclusions can be drawn, it can be postulated that increased echocardiographic epicardial fat accumulation could reflect myocardial fat in subjects with a wide range of adiposity.