TGFB1 and atrial fibrillation: TGF-β1/Smad pathway plays an important role in matrix remodeling, capable of activating atrial fibroblasts differentiation and promoting cellular migration, proliferation and ECM synthesis, which are associated with atrial fibrosis and AF (Guo et al. 2018; Li et al. 2017; Tao et al. 2018).