Lower soluble Klotho and higher fibroblast growth factor 23 serum levels are associated with episodes of atrial fibrillation.

•FGF23 and soluble Klotho play a role in the pathogenesis of atrial fibrillation.•Gradient in the concentrations of peripheral and atrial serum sKlotho and FGF23.•Serum sKlotho gradient correlated with the AF burden in the Holter monitoring.•iFGF23 gradient >28.7 pg/ml was a predictor for atrial fibrillation recurrence.•Lower sKlotho and higher iFGF23 serum levels are associated with episodes of AF.