Objective: The aim of this study was to explore the effects of H2S on myocardial fibrosis induced by hyperthyroxine and expression of STAT signal pathways, miR-21, and miR-29a in the myocardium. Methods: A total of 40 rats were selected and randomly stratified into 4 groups, including the control group (Control), HCM model group (Thy), H2S-intervention model group (Thy+H2S), and H2S-intervention normal group (H2S). Hyperthyroidism rat models were prepared by intraperitoneal injections of L-thyroxine. Rats in the control group received intraperitoneal injections of normal saline. NaHS solution ...