In the AF group, YKL-40 mRNA expression differed significantly among the types of adipose tissue (χ2 = 52.531, P < 0.001); it was significantly more highly expressed in EAT than in SAT or PAT (EAT vs SAT: 3.25 (2.09) vs 1.30 (1.70), P < 0.001; EAT vs PAT: 3.25 (2.09) vs 1.45 (0.80), P < 0.001). The gene discussed is CHI3L1; the disease is atrial fibrillation.