Associação entre gordura epicárdica, fatores de risco cardiovascular e marcadores subclínicos de aterosclerose: Estudo longitudinal de Saúde do Adulto

Abstract

Introduction: Epicardial fat is a fat deposit that has been related to coronary artery disease independently of visceral or subcutaneous fat. However, the mechanism responsible for this association has not yet been elucidated. The objective of the present study was to evaluate the association between automatically measured epicardial fat volume with cardiovascular risk factors, and subclinical markers of atherosclerosis - coronary artery calcium score and endothelial function. Methods: The study sample comprised 470 participants from ELSA-MG, who had valid computed tomography scans and endothelial function evaluated by the peripheral arterial tonometry (PAT) method. The ELSA-MG is one of the Investigation Centers of the ELSA-Brasil cohort, wich aims to study the determinants of cardiovascular disease and diabetes in Brazilian adults. In ELSA-MG, participants were submitted to heart and vessel computed tomography from August 2015 to August 2016. The epicardial fat volume was calculated using a fully automatic method previously described by Shazad et al. and calibrated by the researcher of the present study. The coronary artery calcium score was calculated using the Agatston method and trained specialists blinded for clinical information performed the measurements. Endothelial function was assessed through PAT. Two variables from PAT were used in the present study, mean baseline pulse amplitude, which reflects the basal vascular tone and PAT ratio, which reflects the response to reactive hyperaemia dependent on nitric oxide release. The statistical analyses were performed in three steps: 1- evaluation of the univariable and multivariable association between cardiovascular risk factors (explanatory variables) and epicardial fat volume (response variable), through linear regression; 2- evaluation of the univariable and multivariable association between epicardial fat volume (explanatory variable) and coronary artery calcium score (response variable), through logistic regression; and 3- evaluation of the univariable and multivariable association between epicardial fat volume (explanatory variable) and measures of endothelial function (response variables), through linear regression. Results: In this sample, the mean epicardial fat volume was 111 (86 - 144) mL. Coronary artery calcium score of 0 was detected in 55% of participants. In the multivariable analysis between cardiovascular risk factors and higher epicardial fat volume, the following associations were observed: female gender (0.87 - 95% CI 0.81 - 0.93, p <0.001), increased age (1.02 95% CI 1.01 - 1.02, p <0.001), waist circumference (1.02 95% CI 1.01 - 1.02, p <0.001) and triglycerides (1,001 – IC 95% 1.000 – 1,001, p<0,001). Although epicardial fat volume was positively associated with coronary artery calcium score when above the median (q3 β 1.88 - 95% CI 1.11 - 3.23, p 0.02, q4 β 4 - 95% CI 2.35 - 6.95 , p <0.001) and worse endothelial function – baseline pulse amplitude (q2 β 1,39 – 95% CI 1,21 – 1,60, q3 β 1,84 -95% CI 1,60 – 2,12, q4 β 2,02 – 95% CI 1,76 – 2,33); PAT ratio (q2 β 0,84 95% CI 0,77 – 0,87, q3 β 0,79 95% CI 0,73 – 0,86, q4 β 0,71 95% CI 0,66 – 0,77) in univariable analysis, the association only remained statistically significant after adjusting for cardiovascular risk factors with worse endothelial function, but not with coronary artery calcium score. Conclusion: Our results suggest that the increase of epicardial fat volume may be associated with coronary artery disease through a different pathway from coronary artery calcium score, which reflects the amount of calcified plaques in the vessels, possibly through associations with endothelial dysfunction, microvascular disease and predominantly lipid-rich non-calcified plaques.