Increased volume of epicardial fat is an independent risk factor for accelerated progression of sub-clinical coronary atherosclerosis.

Background: Epicardial adipose tissue (EAT), a metabolically active visceral fat depot surrounding the heart, has been implicated in the pathogenesis of coronary artery disease (CAD) through possible paracrine interaction with the coronary arteries. We examined the association of EAT with metabolic syndrome and the prevalence and progression of coronary artery calcium (CAC) burden.

Methods: CAC scan was performed in 333 asymptomatic diabetic patients without prior history of CAD (median age 54 years, 62% males), followed by a repeat scan after 2.7±0.3 years. CAC progression was defined as >2.5mm(3) increase in square root transformed volumetric CAC scores. EAT and intra-thoracic fat volumes were quantified using a dedicated software (QFAT), and were examined in relation to the metabolic syndrome, baseline CAC scores and CAC progression.

Results: Both epicardial and intra-thoracic fat were associated with metabolic syndrome after adjustment for conventional cardiovascular risk factors, but the association was attenuated after additional adjustment for body mass index. EAT, but not intra-thoracic fat, showed significant association with baseline CAC scores (odds ratio [OR] 1.13, 95% confidence interval [CI] 1.04-1.22, p=0.04) and CAC progression (OR 1.12, 95% CI 1.05-1.19, p<0.001) after adjustment for conventional measures of obesity and risk factors.

Conclusion: EAT volume measured on non-contrast CT is an independent marker for the presence and severity of coronary calcium burden and also identifies individuals at increased risk of CAC progression. EAT quantification may thus add to the prognostic value of CAC imaging.