Objective  To explore the clinical value of the plasma microRNA-21(miRNA-21) level in prediction of myocardial ischemia degree and evaluation of prognosis in patients with acute myocardial infarction (AMI).

  Methods  A total of 150 patients with acute ST-segment elevation myocardial infarction were selected as study objects, and were divided into mild group (58 cases, SYNTAX scores≤22), moderate group (48 cases, SYNTAX scores ranging from 23 to 32) and severe group (44 cases, SYNTAX scores ≥33) according to the myocardial ischemia degree. The plasma levels of miRNA-21, biochemistry indexes and Gensini scores were compared among three groups before and after treatment. The correlations between plasma miRNA-21 level and the Gensini scores, SYNTAX scores were analyzed by Pearson linear correlation analysis. After follow-up for one year, the patients with AMI were divided into non-MACE group (108 cases) and MACE group (42 cases) based on the major adverse cardiovascular events (MACE) of follow-up results. The above indexes were compared between two groups. Multiple Logistic regression analysis was used to evaluate the correlations between the above indicators and prognosis. The diagnostic performance of plasma miRNA-21 level in AMI patients was analyzed by receiver operating characteristic (ROC) curve.

  Results  The plasma levels of miRNA-21, Gensini and SYNTAX scores in the moderate group were lower than the severe group, but higher than the mild group (P < 0.05). The levelsof low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), 2 h postprandial blood glucose (2 hPBG), fasting blood glucose (FBG), homocysteine (Hcy) levels showed significant differences among three groups (P < 0.05), but the levels of prothrombin time (PT) and international standardized ratio (INR) showed no significant differences among three groups (P>0.05). Plasma miRNA-21 level was positively correlated with Gensini score and SYNTAX score (r=0.823, 0.784, P=0.029, 0.033). The plasma level of miRNA-21 in the MACE group was higher than in the non-MACE group (P < 0.001). The index of miRNA-21, Gensini and SYNTAX scores were the risk factors of prognosis after one-year follow-up in patients with AMI (OR=3.656, P=0.013; OR=2.887, P=0.036; OR=2.913, P=0.029). When the cut-off value of plasma miRNA-21 was 3.25, the area under the curve was 0.824, the sensitivity was 83.9%, and the specificity was 87.6% (P=0.023).

  Conclusion  The plasma levels of miRNA-21 can evaluate the myocardial ischemia degree of patients with AMI, and has good predictive value on the short-term prognosis.