Abstract:Objective To study the serum level of microRNAs-21 (miR-21) in the patients with acute coronary syndrome (ACS) to explore the diagnostic value of miR-21 in ACS and the relationship between miR-21 and plaque stability. Methods Forty-five patients with ACS treated from January 2016 to January 2018 were selected as the research object(ACS group), and 45 patients with coronary artery stenosis less than 30% were selected as the control group.After collecting the general data of patients, the serum level of miR-21 was detected by RT-PCR, and the plaque stability was measured by optical coherence tomography (OCT).The area under the curve (AUC) of receiver operating characteristic (ROC) analysis was calculated to determine the value of miR-21 on plaque stability, and the correlation between miR-21 and vulnerable plaque was analyzed. Results The serum miR-21 level in ACS group was significantly higher than that in control group (9.87±0.648 vs 2.37±0.795, P<0.01).AUC value of miR-21 was 0.9814 in diagnosis of ACS; serum miR-21 level was positively correlated with the number of vulnerable plaques, the largest area of lipid core and the number of macrophages (P<0.01). Conclusion Serum miR-21 significantly increases in ACS patients, which has a positive linear correlation with plaque stability and may be used as a diagnotic index and prognostic indicator for ACS.