Association between echocardiographic epicardial fat thickness and circulating endothelial progenitor cell level in patients with stable angina pectoris

Background: Epicardial adipose tissue is associated with coronary artery disease (CAD). Circulating endothelial progenitor cell (EPC) level represents a marker of endothelial dysfunction and vascular health. However, the relationship between epicardial fat and circulating EPC remains unknown. This study aimed to investigate association between echocardiographic epicardial fat thickness (EFT) and circulating EPC level. Hypothesis: Epicardial fat causes inflammation and contributes to progression of CAD. Methods: We enrolled 213 consecutive patients with stable angina, and EFT was determined by echocardiography. Quantification of EPC markers (defined as CD34(+), CD34(+)KDR(+), CD34(+)KDR(+)CD133(+) cells) in peripheral blood samples was used to measure circulating EPCs. All patients were divided into 3 tertiles according to EFT levels: group 1, low tertile of EFT; group 2, middle tertile of EFT; and group 3, high tertile of EFT. Results: Among the 3 groups, CAD disease severity determined by SXscore was negatively correlated with EFT, but the difference did not reach statistical significance (P = 0.066). Additionally, patients in the high and middle tertiles of EFT had higher circulating EPC levels than did those in the low tertile of EFT (P = 0.001 and P < 0.001, respectively). In multivariate analysis, EPC level was significantly associated with echocardiographic EFT (standardized beta = -0.233, P = 0.001), independent of multiple covariates. Conclusions: Epicardial adipose tissue is associated with circulating EPC levels. There was a trend between epicardial fat and severity of CAD, though analysis did not reach statistical significance, and this may be attributed to the interaction between several risk factors of CAD.