Computed tomography (CT) assessed adipose depot quantity and attenuation, a marker of fat quality, is linked to cardiovascular disease (CVD) risk. Prior work has demonstrated a strong association between intra-abdominal visceral fat (VAT) and CVD, but whether sub-compartments of VAT are deferentially associated with CVD is unknown. We examined how omental and mesenteric VAT quantity and quality relate with cardiometabolic health compared to total VAT using CT.
In 50 obese subjects (BMI 45±1 kg/m2, 76% female) we measured anthropometrics, metabolic markers, flow-mediated dilation (FMD) by vascular ultrasound of the brachial artery, and assessed volume (cm3) and attenuation (Hounsfield units, HU) of total, mesenteric and omental VAT depots by CT. Spearman correlation coefficients assessed correlations between fat depots and CVD risk factors.
Omental VAT volume was less than mesenteric VAT (p<0.05). Omental VAT had the most negative attenuation (-92±11 HU) compared to mesenteric and total VAT (-85±9 and -85±8 HU, p<0.001) suggesting a more proatherogenic phenotype. Mesenteric and total VAT volume correlated positively with waist circumference, glucose, insulin, HOMA, and triglycerides (TG, p<0.05 all), while omental VAT volume correlated positively with glucose, insulin and HOMA (p<0.05 all). Total VAT volume correlated negatively with FMD (p<0.05) indicating poor macrovascular function in subjects with high amounts of total VAT. No association between FMD and sub-compartments of VAT volume was observed. Attenuation values for all three visceral fat depots correlated positively with weight and hip circumference, but only total VAT correlated positively with BMI (p<0.001, all). Mesenteric and total VAT HU correlated negatively with TG (p<0.05).
Our data indicates that there is heterogeneity among sub-compartments of intra-abdominal visceral fat. These findings provide new insight to how abdominal fat distribution is related to systemic cardiometabolic health in obesity.