Impact of waist circumference and abdominal fat distribution on coronary artery disease severity stratified by computed tomography-derived SYNTAX score
Authors: Oyama Y , Otagiri K , Miyagi T , Sakai T , Kitabayashi H 
Published: October 2024

Abstract

Background
Waist circumference (WC) is the most convenient anthropometric measure of obesity. Recently, abdominal fat distribution (AFD) has been identified as a more important risk factor for coronary artery disease (CAD) than the absolute amount of adipose tissue. However, studies examining the impact of body composition indicators (BCIs) on CAD severity are lacking. The computed tomography (CT)-derived SYNTAX score (CT-SXscore) is a feasible method for grading CAD severity based on coronary CT angiography (CTA) findings.

Purpose
This study was aimed to evaluate the association between BCI and CAD severity using the CT-SXscore.

Methods
We enrolled consecutive patients with suspected CAD who underwent CTA using a 320-row multidetector CT scanner between October 2014 and March 2020. Plain abdominal CT was also performed at the umbilical level to measure the visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) areas. The total adipose tissue (TAT) area was calculated as the sum of VAT and SAT. To assess the AFD, the VAT/SAT (V/S) ratios were also calculated as the VAT area divided by the SAT area in each case. WC was measured by tracing the body contour at the umbilical level in CT images. The severity of coronary artery stenosis was assessed using CTA. Significant stenosis was defined as a stenosis diameter of ≥50%. The CT-SXscore was calculated in patients with more than one significant stenoses. Each stenotic lesion was evaluated to calculate the CT-SXscore in the same manner as the invasive coronary angiography assessment. We assessed the effects of BCI [i.e., WC, body mass index (BMI), each adipose tissue area, and V/S ratios] on the CT-SXscores.

Results
308 eligible patients (mean age, 70.9 ± 10.6 years; 69.5% males) were evaluated. The median values of WC, BMI, TAT, SAT, VAT, and V/S ratio were 84.8 cm, 23.6 kg/m2, 198.2 cm2, 111.8 cm2, 81.0 cm2, and 0.67, respectively. Although WC showed a significant correlation with BMI, TAT, SAT, and VAT area, no correlation was observed between WC and V/S ratio (Figure1). The CT-SXscore showed no association with WC, BMI, and TAT area; however, it exhibited a weak negative correlation with the SAT area and a weak positive correlation with the VAT area. Additionally, a strong correlation was observed between the CT-SXscore and V/S ratio. In the multivariate regression analysis, WC, BMI, TAT, SAT, and VAT were no longer associated with the CT-SXscore after adjusting for traditional coronary risk factors, whereas the V/S ratio remained as the only independent predictor of CAD severity based on the CT-SXscore (Figure2).

Conclusions
WC was strongly correlated with other BCIs, except for the V/S ratio; however, it could not be identified as a predictive factor of CAD severity. Among the BCIs, only the V/S ratio was an independent predictor of CAD severity, indicating that the AFD revealed by the V/S ratio may be a more important risk factor for progression of CAD than other BCIs.Figure1Figure2