FNDC5 and atrial fibrillation: Multivariable analysis showed that an age ≥ 64 years; the presence of atrial fibrillation, diabetes mellitus, CKD stages 1–3 and dilated cardiomyopathy; an LAVI ≥ 39 mL/m2; and serum levels of hs-CRP ≥ 6.10 mg/L, irisin ≤ 7.2 ng/mL and visfatin ≤ 1.1 ng/mL were predictors of poor clinical outcome in HFpEF.