Visceral Adipose Tissue, Aortic Distensibility and Atherosclerotic Cardiovascular Risk Across Body Mass Index Categories.

Background: While obesity is a well-established risk factor for cardiovascular disease, the relationship between visceral obesity, as assessed by imaging modalities of visceral adipose tissue (VAT), and the risk of atherosclerotic cardiovascular disease (ASCVD) has been insufficiently explored in large-scale studies, particularly across different body mass index (BMI) categories.

Aim: We aimed at investigating the association between VAT and aortic distensibility as well as risk of ASCVD and comparing the magnitude of VAT-aortic distensibility and VAT-ASCVD association across BMI groups.

Methods: Leveraging data from the UK Biobank, we examined the association between body weight-normalized VAT (VAT-index, VATi), assessed via abdominal MRI (VATi-MRI) or dual-energy X-ray absorptiometry (DXA; VATi-DXA), and aortic distensibility (a direct local measure of aortic stiffness) as well as the risk of atherosclerotic cardiovascular disease (ASCVD) over a median follow-up period of 4.7 years.

Results: The abdominal MRI sub-cohort of the UK Biobank included 36829 individuals, among which 28888 individuals were additionally evaluated using DXA. VATi was associated with decrease in ascending aortic distensibility (VATi-MRI adjusted β = -0.05 (95% CI -0.07 to -0.04, p<0.001); VATi-DXA adjusted b = -0.04 (95% CI -0.06 to -0.03, p<0.001) and increased risk of ASCVD (VATi-MRI: HR 1.16 (95% CI 1.09-1.23, p<0.001); VATi-DXA: 1.21 (95% CI 1.13-1.3), p<0.001), adjusted for age, sex, socioeconomic status, lifestyle factors, and cardiometabolic comorbidities. Across BMI categories, these associations were more pronounced in non-obese individuals. The cumulative incidence of ASCVD was higher in individuals with high VATi compared to those with low VATi, consistently observed across BMI categories. With a total of 1,462 ASCVD events, incidence rates were higher in individuals with high VATi compared to low VATi across all BMI categories: 5.5% vs. 2.2% in the normal BMI group, 5.7% vs. 2.5% in the overweight group, and 5.9% vs. 2.1% in the obese group (p log-rank <0.001). Overall, in the multivariable-adjusted Cox proportional hazard model, VATi was associated with 16% increased ASCVD risk (HR 1.16 [95% CI 1.09-1.23], p<0.001), but this association was attenuated when adjusted for the clinical marker of central obesity, the waist-to-hip ratio (WHR). In contrast, the association remained significant in the normal BMI group even after adjusting for WHR (HR for VATi-MRI 1.22 (95 % CI 1.06-1.42, p<0.01; VATi-DXA 1.35 (95% CI 1.11-1.65, p<0.01).

Conclusions: Visceral obesity, measured by advanced imaging modalities, is linked to greater aortic stiffness and elevated risk of ASCVD, independent of BMI, in individuals without known ASCVD. Notably, these associations were observed mostly in non-obese subjects, with the strongest associations found in the normal BMI group. These findings highlight the additional predictive value of visceral obesity over general measures like BMI or WHR, particularly among non-obese individuals.