Given that Fgf21 exert function mainly through fibroblast growth factor 21 receptor-1(FgfR1) and its co-receptor β-Klotho in the heart, we also performed immunofluorescence to assess expression level of FgfR1 and β-Klotho in SR and AF patients. This evidence concerns the gene FGFR1 and atrial fibrillation.