TGFB1 and atrial fibrillation: There is substantial evidence that angiotensin‐II (Ang‐II) can up‐regulate TGF‐β1 and collagen expression in vitro and in vivo, and Ang‐II plays an important role in atrial fibrosis and AF through its regulation of TGF‐β1.7, 8, 9, 10, 11