Introduction: MI is defined by the presence of myocardial necrosis, which is caused by acute and persistent ischemia and hypoxia of the coronary artery. In recent years, its incidence rate has been on the rise in China.

Methods: GSE34198, GSE97320 and GSE141512 datasets were download for DEG analysis. KEGG pathway analysis, GO analysis, GSEA and PPI network construction were performed. Later, target genes of candidate miRNAs were predicted. Next, echocardiography was conducted to detect the effects of miR-29 on left ventricular structure and cardiac function in vivo, and H&E staining was adopted to study the effects of miR-29 on angiogenesis and fibrosis in vivo. Furthermore, Western blotting was employed to investigate the effects of miR-29 inhibition on the expressions of proteins related to the PI3K\mTOR\ HIF-1α\VEGF pathway.

Results: There were 162 DEGs involved in MI. GO analysis revealed that inflammatory responses, negative regulation of apoptosis and innate immune response were the main enriched biological processes. KEGG analysis manifested that DEGs were mainly enriched in the PI3K/Akt signaling pathway, and GSEA demonstrated that they were mainly enriched in the PI3K/Akt/mTOR, HIF and VEGF pathways. Moreover, target gene prediction showed that miR-29 was lowly expressed in MI. According to Masson's trichrome staining, miR-29 inhibition promoted angiogenesis, reduced fibrosis, and increased the protein expressions of p-PI3K, p-mTOR, HIF-1α, and VEGF.

Conclusions: MiR-29 may play an important role in the growth and development of MI. After inhibition of miR-29, the PI3K/mTOR/HIF-1α/VEGF pathway is activated to alleviate MI.