Associations of visceral and abdominal subcutaneous adipose tissue with markers of cardiac and metabolic risk in obese adults

Abstract

Objective: Visceral (VAT) and abdominal subcutaneous (SAT) adipose tissues contribute to obesity but may have different metabolic and atherosclerosis risk profiles. We sought to determine the associations of abdominal VAT and SAT mass with markers of cardiac and metabolic risk in a large, multiethnic, population-based cohort of obese adults.

Design and methods: Among obese participants in the Dallas Heart Study, we examined the cross-sectional associations of abdominal VAT and SAT mass, assessed by magnetic resonance imaging (MRI) and indexed to body surface area (BSA), with circulating biomarkers of insulin resistance, dyslipidemia, and inflammation (n = 942); and with aortic plaque and liver fat by MRI and coronary calcium by computed tomography (n = 1200). Associations of VAT/BSA and SAT/BSA were examined after adjustment for age, sex, race, menopause, and body mass index.

Results: In multivariable models, VAT significantly associated with the homeostasis model assessment of insulin resistance (HOMA-IR), lower adiponectin, smaller LDL and HDL particle size, larger VLDL size, and increased LDL and VLDL particle number (p < 0.001 for each). VAT also associated with prevalent diabetes, metabolic syndrome, hepatic steatosis, and aortic plaque (p < 0.001 for each). VAT independently associated with C-reactive protein but not with any other inflammatory biomarkers tested. In contrast, SAT associated with leptin and inflammatory biomarkers, but not with dyslipidemia or atherosclerosis. Associations between SAT and HOMA-IR were significant in univariable analyses but attenuated after multivariable adjustment.

Conclusion: VAT associated with an adverse metabolic, dyslipidemic, and atherogenic obesity phenotype. In contrast, SAT demonstrated a more benign phenotype, characterized by modest associations with inflammatory biomarkers and leptin, but no independent association with dyslipidemia, insulin resistance, or atherosclerosis in obese individuals. These findings suggest that abdominal fat distribution defines distinct obesity sub-phenotypes with heterogeneous metabolic and atherosclerosis risk.

Figure 1. Representative Examples of Abdominal Fat and Aortic Plaque by MRI in Two Subjects with Divergent Cardiovascular and Metabolic Phenotypes

Panel A: Transverse abdominal MRI images of VAT and SAT (upper panel) and aortic plaque (lower panel) in a 21 year old black female with BMI of 36 kg/m² and total body fat of 4.2 kg (41%) demonstrate very low VAT (0.22 kg/m²) and high SAT (4.45 kg/m²), and no aortic plaque (0%). Panel B: In contrast, images of VAT and SAT (upper panel) and aortic plaque (lower panel) in a 59 year old white male with a BMI of 31.4 kg/m² and total body fat of 4.0 kg (34%) demonstrate very high VAT (1.80 kg/m²) and low SAT (1.46 kg/m²), and high aortic plaque (18%). BMI, body mass index; LDL, low-density lipoprotein; MRI, magnetic resonance imaging; SAT, subcutaneous adipose tissue; VAT, visceral adipose tissue

Figure 2. Adjusted Prevalence of Aortic Plaque by Tertile of VAT/BSA or SAT/BSA in Obese Adults

The adjusted prevalence of aortic plaque increases significantly across sex-specific tertiles of VAT, but decreases across tertiles of SAT, in obese adults. Adjusted for age, sex, race, menopausal status (women only), hypertension, diabetes, smoking, hypercholesterolemia, low HDL cholesterol, glucose-lowering medication, lipid-lowering medication, aspirin, VAT/BSA, and SAT/BSA. p-value for trend across tertiles BSA, body surface area; SAT, subcutaneous adipose tissue; Tert, tertile; VAT, visceral adipose tissue