Relationship between epicardial fat volume and carotid intima media thickness in patients with chest pain and unobstructed coronary arteries

Abstract

Introduction: Epicardial fat (EF) is associated with the development of atherosclerosis through release of inflammatory cytokines which has a local effect on coronary arteries and a systemic effect on large vessels such as the carotid arteries. The first structural change detected in atherosclerosis is an increase in intima media thickness which is also associated with an underlying inflammatory state. Whether EF is associated with carotid intima media thickness (CIMT), a marker of subclinical atherosclerosis predictive of future cardiovascular events, in patients without coronary disease is unknown. Purpose: We investigated whether epicardial fat volume (EFV) is associated with CIMT in patients presenting with chest pain without coronary disease on CTCA. Methods: Patients attending cardiology outpatient clinics with stable chest pain suggestive of myocardial ischemia and referred for diagnostic CTCA were recruited in this study. Patients were excluded if they had ≥ 50% luminal stenosis, known ischemic or valvular heart disease, left ventricular hypertrophy or an ejection fraction <55%. We subdivided the population into those without coronary disease (CAD-; luminal stenosis 0%) and those with coronary disease (CAD+; luminal stenosis 1-49%). EFV (cm3) was measured using 64-channel CT scanner with every fourth serial slice of the parietal pericardium from the bifurcation of the pulmonary artery to diaphragm with an attenuation range of (-45,-190) Hounsfield Units. CIMT (mm) was measured using Bmode ultrasound. Data were summarised using mean (SD), median (IQR) or proportion depending on data type and distribution. Inferential analysis was undertaken using multivariable regression on CIMT as the outcome variable. Subsequent subgroup analysis on CIMT using the presence or absence of coronary disease was also undertaken. Results: We recruited 134 patients of whom 59 (44%) were CAD-and 75 (56%) were CAD+. The mean age of the total population was 59 years (9.8), 49% were male. Mean EFV was 137.0 cm3 (55.4). Mean CIMT was 640 mm (130). In the total population, multivariable regression modelling using CIMT as the output variable identified age (b = +4.41, P < 0.001) as a significant predictor while the presence of coronary disease (b = +0.39, P = 0.051) almost reached significance. However, EFV was not a predictor (b = +0.34, P = 0.12) of CIMT. In the subgroup analysis, univariate regression of CIMT and EFV identified a significant positive association (b = +0.78, P = 0.04) in patients with CAD+ but not in patients with CAD-(b = +0.28, P = 0.32). Conclusion: In patients without coronary disease on CTCA, EFV is not associated with subclinical atherosclerosis as measured by CIMT. However, we found an association between EFV and CIMT in patients with coronary disease. It is likely both CIMT and EFV are associated with coronary disease but the lack of association between EFV and CIMT suggests different mechanisms in the development of vascular atherosclerosis.L620122468 <br />