FGF19 and atrial fibrillation: During this period, a total of 11 non‐AF controls and 15 AF patients were evaluated for faecal BAs and plasma FGF19 levels, and a correlation analysis showed that plasma FGF19 levels were negative with faecal UDCA correlated (r = −0.174, p = 0.385) and positively correlated with faecal LCA (r = 0.120, p = 0.280).