YKL-40 is highly expressed in the epicardial adipose tissue of patients with atrial fibrillation and associated with atrial fibrosis

Background YKL-40 (CHI3L1) is a novel biomarker for inflammation, tissue remodeling, and fibrosis, as well as cardiovascular diseases. We investigated the association between YKL-40 expression in epicardial adipose tissue (EAT) and atrial fibrosis in patients with atrial fibrillation (AF). Methods Blood samples, subcutaneous adipose tissue (SAT), paracardial adipose tissue (PAT), EAT, and adjacent atrial myocardium were acquired from patients receiving coronary artery bypass grafts. The patients were divided into the AF group (n = 28) and the sinus rhythm (SR) group (n = 36). Results We did not detect a significant difference in the serum YKL-40 levels in the SR and AF groups (P = 0.145). Quantitative real-time PCR showed that YKL-40 (CHI3L1) mRNA levels in the EAT were significantly higher than in the SAT or PAT of AF patients, or the EAT of SR patients (All P