FNDC5 and atrial fibrillation: Multivariate regression analysis showed that atrial fibrillation (odds ratio [OR] = 0.95; p = 0.010), LAVI < 39 mL/m2 (OR = 1.23; p = 0.001), irisin levels ≥ 10.8 ng/mL (OR = 1.73; p = 0.001), and NT-proBNP < 1540 pmol/mL (OR = 1.47; p = 0.001) independently predicted HFimpEF.