ACTA1 and Myocardial fibrosis: In myocardial fibrosis after ischemia, circHNRNPH1 competitively binds to miR-216-5p, induces the expression of Smad7 to accelerate the degradation of TGF-β1, inhibits the migration of myofibroblasts and the expression of α-SMA and col-I, and alleviates the progression of myocardial fibrosis.