Objective · To investigate the value of serum miR-133a in early diagnosis and the assessment of 30-day incidence of cardiovascular adverse events in patients with acute myocardial infarction (AMI). Methods · Ninety patients with acute chest pain within 6 h were included, and 63 cases of AMI, 13 cases of unsangina pectoris (UAP) and 14 cases of control (chest pain of other causes) were finally diagnosed. The levels of troponin I (cTnI), creatine kinase MB (CK-MB) and myoglobin (Mb) were measuredelectrochemical fluorescence. Quantitative real-time PCR (qPCR) was used to detect the of miR-133a in the serum of patients immediately after admission and 24 h after percutaneous coronary intervention (PCI). The Gensini score of patients who underwent coronary angiography was recorded. The incidence of cardiovascular adverse events was observed within 30 days. Spearman correlation analysis, multivariate Logistic regression analysis and receiver operator characteristic curve (ROC curve) were used to analyze the corresponding data. Results · The of miR-133a in the AMI group was significantly higher than that in the UAP group and the control group (both PPCI 0.716-0.917), and the AUC of 30 days cardiovascular adverse event was 0.700 (95% CI 0.535-0.865). Conclusion · The of miR-133a in patients with AMI is significantly increased, which is expected to be a biomarker for early diagnosis of AMI. The level of miR-133a in serum may be related to the severity of coronary artery disease and short-term prognosis.