We observed that circNFIB upregulation by AAT1 overexpression alleviated TGF-β1-induced myocardial fibrosis by inhibiting the Wnt/β-catenin and p38 MAPK pathways; the activation of these pathways was significantly inhibited after siRNA-mediated silencing of circNFIB expression. This evidence concerns the gene TGFB1 and Myocardial fibrosis.