title: The relationship of ectopic lipid accumulation to cardiac and vascular function in obesity and metabolic syndrome.
abstract: Storage of lipid in ectopic depots outside of abdominal visceral and subcutaneous stores, including within the pericardium and liver, has been associated with obesity, insulin resistance, and cardiovascular risk. We sought to determine whether anatomically distinct ectopic depots were physiologically correlated and site-specific effects upon cardiovascular function could be identified. Obese subjects (n = 28) with metabolic syndrome but without known atherosclerotic disease and healthy controls (n = 18) underwent magnetic resonance imaging (MRI) and proton MR spectroscopy (MRS) to quantify pericardial and periaortic lipid volumes, cardiac function, aortic compliance, and intrahepatic lipid content. Fasting plasma lipoproteins, glucose, insulin, and free-fatty acids were measured. Pericardial and intrahepatic (P < 0.01) and periaortic (P < 0.05) lipid volumes were increased in obese subjects vs. controls and were strongly and positively correlated (P <or= 0.01) but independent of BMI (P = NS) among obese subjects. Intrahepatic lipid was associated with insulin resistance (P < 0.01) and triglycerides (P < 0.05), whereas pericardial and periaortic lipid were not (P = NS). Periaortic and pericardial lipid positively correlated to free-fatty acids (P <or= 0.01) and negatively correlated to high-density lipoprotein (HDL) cholesterol (P < 0.05). Pericardial lipid negatively correlated to cardiac output (P = 0.03) and stroke volume (P = 0.01) but not to left ventricular ejection fraction (P = 0.46). None of the ectopic depots correlated to aortic compliance. In conclusion, ectopic storage of lipid in anatomically distinct depots appeared tightly correlated but independent of body size. Site-specific functional abnormalities were observed for pericardial but not periaortic lipid. These findings underscore the utility of MRI to assess individual differences in ectopic lipid that are not predictable from BMI.
authors.affiliation: Department of Medicine, Section of Cardiology, Boston University School of Medicine, Boston, Massachusetts, USA. frruberg@bu.edu
authors.forename: Frederick L
authors.initials: FL
authors.lastname: Ruberg
authors.forename: Zhongjing
authors.initials: Z
authors.lastname: Chen
authors.forename: Ning
authors.initials: N
authors.lastname: Hua
authors.forename: Sherman
authors.initials: S
authors.lastname: Bigornia
authors.forename: Zifang
authors.initials: Z
authors.lastname: Guo
authors.forename: Kevin
authors.initials: K
authors.lastname: Hallock
authors.forename: Hernan
authors.initials: H
authors.lastname: Jara
authors.forename: Michael
authors.initials: M
authors.lastname: LaValley
authors.forename: Alkystis
authors.initials: A
authors.lastname: Phinikaridou
authors.forename: Ye
authors.initials: Y
authors.lastname: Qiao
authors.forename: Jason
authors.initials: J
authors.lastname: Viereck
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Apovian
authors.forename: James A
authors.initials: JA
authors.lastname: Hamilton
mesh_terms: D000273:Adipose Tissue; D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D001808:Blood Vessels / Q000378:metabolism / Q000503:physiopathology*; D002318:Cardiovascular Diseases / Q000000981:diagnostic imaging / Q000209:etiology* / Q000378:metabolism / Q000503:physiopathology; D002320:Cardiovascular Physiological Phenomena; D016022:Case-Control Studies; D002828:Choristoma / Q000150:complications* / Q000000981:diagnostic imaging / Q000378:metabolism; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D050356:Lipid Metabolism / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D024821:Metabolic Syndrome / Q000150:complications / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology*; D008875:Middle Aged; D009765:Obesity / Q000150:complications / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology*; D011859:Radiography; D016277:Ventricular Function, Left / Q000502:physiology; D055815:Young Adult