The regulation of profibrotic mediators, important in the process of atrial fibrosis, i.e., TGF-β, CTGF, MAPK signalling pathway, Ang II, IGF-1 [3,115,116], involves various miRNA molecules directly associated with atrial fibrosis in AF, that is: miR-21, miR-26a, miR-29b, miR-30a, miR-133, miR-101, miR-132, miR-208a/b [3,4,113,117] (Figure 3). Here, AGT is linked to atrial fibrillation.