Increased epicardial adipose tissue in patients with slow coronary flow phenomenon

Slow coronary flow (SCF) is an angiographic finding characterised by delayed opacification of epicardial coronary arteries without obstructive coronary disease. Epicardial adipose tissue (EAT), localised beneath the visceral pericardium, is a metabolically active endocrine and paracrine organ with possible interactions within the heart. EAT and low-grade inflammation play major roles in the atherosclerotic vascular processes and may be important in other coronary pathologies such as SCF.

To investigate whether EAT and C-reactive protein (CRP) are increased in patients with isolated SCF compared to normal subjects.

The present study was cross-sectional and observational, consisting of 66 individuals who underwent coronary angiography with a suspicion of coronary artery disease and who had angiographically normal coronary arteries of varying coronary flow rates. The relationship between EAT, CRP and SCF phenomenon was investigated. Thirty-three patients with isolated SCF (mean age: 56 ± 10 years) and 33 age- and gender-matched control participants with normal coronary flow (NCF), but without SCF, (mean age: 55 ± 10 years) were included in the study.

EAT thickness was significantly increased in the SCF group compared to the NCF group (7.1 ± 2.7 vs. 4.7 ± 1.9 mm, p < 0.001). Body mass index (BMI, p < 0.001) and the percentage of isolated SCF (p = 0.002) were significantly higher in patients with increased EAT thickness. CRP was not related to SCF. When we performed multiple logistic regression analysis, only increased EAT thickness was related to the presence of SCF (OR 1.720, 95% CI 1.175-2.516, p = 0.005) independent of BMI and CRP.

This study revealed, for the first time, a significant increase in EAT thickness in patients with SCF compared to NCF. We believe that further studies are needed to clarify the role of adipose tissue in patients with SCF.