Subcutaneous adipose tissue is associated with decreased cardiovascular events in patients with a lower body mass index suspected of coronary artery disease

Introduction Abdominal fat distribution (AFD), quantified by the ratio of visceral adipose tissue (VAT) to subcutaneous adipose tissue (SAT) areas (V/S ratio), may be associated with an increased risk of cardiovascular disease (CVD). Although VAT has traditionally been considered the primary contributor to CVD risk, the role of SAT remains less well understood. Despite the common use of the body mass index (BMI) as an indicator of obesity, the associations of AFD indices (V/S ratio, SAT, and VAT) and BMI-stratified physique with CVD outcomes have not been fully elucidated. Purpose This study aimed to investigate the effect of AFD and BMI-stratified physique on long-term cardiovascular outcomes. Methods In total, 942 consecutive patients (mean age 66.7 years; 42.5% female) with suspected coronary artery disease who underwent coronary computed tomography (CT) angiography were evaluated. Plain abdominal CT was also performed at the umbilical level to quantify SAT and VAT areas, and the V/S ratio was calculated as an AFD index. Patients were stratified into two groups based on the median BMI (23.6 kg/m²) and further categorized into high and low groups according to the median V/S ratio, SAT, and VAT (0.625, 115.1 cm², and 76.9 cm², respectively). Associations between these AFD indices and 5-year clinical outcomes were assessed within each BMI group. The primary outcome was major adverse cardiac events (MACEs), including all-cause death, any coronary revascularization, acute coronary syndrome, and emergent hospitalization for cardiac causes. Results Kaplan–Meier analysis showed significantly lower MACE-free survival rates among patients with low BMI and a high V/S ratio than those with a low V/S ratio. Lower MACE-free survival rates were also observed in both BMI groups among patients with low SAT, whereas no significant differences were seen between VAT groups (Figure). A high V/S ratio and high SAT were associated with a 57% increase and a 46% decrease in the risk of MACEs, among patients with low BMI (hazard ratio [HR], 1.57; 95% confidence interval [CI], 1.09–2.27; p = 0.015 for high V/S ratio; HR, 0.54; 95% CI, 0.33–0.89; p = 0.015 for high SAT) in multivariable Cox regression analysis adjusted for traditional coronary risk factors (Table). Conclusion In patients with low BMI, a higher V/S ratio was associated with an increased risk of MACEs, whereas greater SAT was linked to a reduced risk. VAT alone showed no significant association with cardiovascular events. Although VAT and SAT contribute to the V/S ratio, SAT appears to have a stronger influence on cardiovascular outcomes. Thus, SAT may exert a protective effect against CVD progression in individuals with low BMI.