Abstract P229: Small Visceral Adipose Volumes and Quality Associated with Aortic and Coronary Artery Calcification in Women with SLE

Abstract

Introduction: Women with systemic lupus erythematosus (SLE) have an increased risk of cardiovascular disease (CVD) not explained by CVD or SLE risk factors. Small visceral fat volumes of the heart and aorta quantified by computed tomography (CT) have been associated with subclinical CVD. Additionally, fat quality, assessed by CT attenuation (Hounsfield Units, HU), may confer CVD risk. Hypothesis: Low density (more negative HU) fat is associated with aorta and coronary artery calcification (AC/CAC) in women with SLE independent of fat volume and BMI or waist-to-hip ratio (whratio). Methods: CT scans from clinically CVD-free SLE women (n=143) were used to quantify AC/CAC (Agatston score) and aortic perivascular and total heart fat tissue (aPVAT, TAT) volumes. Fat quality was assessed using average HU (aorta:avgHUa; heart:avgHUh). Logistic regression models (any AC/CAC) were used and final models were adjusted for BMI or whratio. Results: In this study, AC/CAC was detected in 118/143 women (AC score (median (IQR)): 70(10-381) CAC score 1.4(0-30)). SLE women with any AC/CAC were more likely to be hypertensive and postmenopausal with a greater BMI (all p<0.05). Those with any AC had elevated circulating levels of CRP, fibrinogen and total cholesterol, while those with any CAC also had higher triglyceride, homocysteine, C3 and C4 (all p<0.05). SLE with any AC/CAC had greater volumes (cm 3 ) of TAT (111 (84-137)) and aPVAT (34 (27-45)) when compared to those with no AC/CAC (TAT 71 (52-102); aPVAT 27 (23-30), both<0.01). SLE women with any AC/CAC had a more positive avgHUa (mean(std): -83.4(1.9)) when compared to those with no AC/CAC (-84.5(1.6)), p<0.03). In logistic regression analysis, TAT (OR[95%]: 2.8[1.4-5.6]), aPVAT (4.9[1.7-14]) and avgHUa (1.9[1.1-3.1]) were associated with any AC/CAC (all p<0.03). After adjusting for BMI or whratio, TAT remained associated with any AC (2.1[1.0-4.2] and 2.8[1.4-5.5], p<0.05) and any CAC (1.7[1.0-2.7] and 2.4[1.5-3.7], all p<0.05). Both aPVAT and avgHUa were attenuated when adjusting for BMI with any AC; however, avgHUa remained significant with any CAC (1.9[1.2-3.0), p<0.01). The association with any AC and CAC remained significant when adjusting for whratio for both aPVAT (5.4[1.8-16], 1.9[1.2-3.1], both p<0.01) and avgHUa (1.7[1.0-2.9], 1.9[1.2-3.1]) both p<0.04).When evaluating fat volume and quality with any CAC, avgHUa (2.1[1.3-3.5],p<0.01) attenuated aPVAT(1.3[0.86-1.8],p=0.2). Conclusions: Fat volumes surrounding the heart and aorta are greater and, contrary to our hypothesis, the avgHU was more positive in clinically CVD-free SLE women with calcification. This higher density may reflect unhealthy fibrotic fat. AC generally precedes CAC development and the independent association of both aPVAT and avgHUa suggest that the relationship between fat volume and quality may be an indicator of more advanced vascular calcification and CVD risk.