Correlation Between Plasma MicroRNA Levels And Acute Myocardial Infarction

Objective To evaluate the value of changes in plasma miR-92a and miR-126 levels in acute myocardial infarction.A preliminary study of the standardized procedures for detecting microRNAs（miRNAs）in plasma provides a reliable reference for clinical practice.Methods Forty patients with AMI（Acute myocardial infarction）who were admitted to the General Hospital of Northern Theater Command from October 2017 to April 2018were selected as myocardial infarction（AMI）group,and 41 healthy subjects were selected as control group.The relative expression levels of miR-92a and miR-126 in plasma of patients with AMI and healthy subjects were monitored by qPCR（Real-time fluorescence quantitative polymerase chain reaction）.Binary logistic regression was used to establish risk scores based on age,miR-126 and miR-92a values,to construct an acute myocardial infarction risk assessment model,and to assess the risk of AMI in each patient.ROC curve（The receiver operating characteristic curve）and bootstrap resamping were used to evaluate the predictive efficacy of the model on the risk of AMI,and to determine its diagnostic and predictive value for AMI.Eight patients with AMI who were treated in the General Hospital of Northern Theater Command in September 2017,and 23 patients with healthy subjects were selected for miRNA standardization.The effects of dietary status,anticoagulant selection,plasma storage conditions,and hemolysis on plasma miRNA quantification and AMI risk scores were analyzed.The effects of extraction,reverse transcription and qPCR on plasma miRNA quantification were analyzed during the experiment,and the results were verified by 16 clinical specimens.Results The levels of miR-92a and miR-126 in the patients with AMI were significantly lower than those in the control group,and the difference was statistically significant（p<0.05）.The risk score formula is RS=∑_iw_ix_i+2.573.In the myocardial infarction risk assessment model,age was a risk factor for AMI（OR=1.068,95%CI,1.018-1.158）,miR-92a and miR-126 were protective factors for AMI(OR_92a=0.363,95%CI 0.171-0.770;OR₁₂₆=0.446,95%CI 0.245-0.811),That is,the older the study,the lower the level of miR-126 and miR-92a in plasma,the higher the risk score,the higher the risk of AMI.The AUC（area under the curve）of the AMI risk assessment model was 0.938（95%CI 0.862-0.980）,the sensitivity was 0.95（95%CI 0.831-0.994）;the specificity was 0.893（95%CI 0.679-0.928）.Bootstrap resamping test,P<0.05.In the miRNA detection standardization research,the pre-analytical influencing factors were mainly derived from dietary status,anticoagulant selection and storage conditions.Hemolysis was positively correlated with miRNA levels,but there was no significant change in risk score after internal reference calibration.The risk score immediately increased after eating and began to decline after reaching the peak at 2 h.When using lithium heparin anticoagulant,the miRNA quantification and risk scores decreased,while EDTA-K2 and sodium citrate anticoagulation had little effect on miRNA detection results.After storage of plasma at 4℃for 1 week,both miRNA quantification and risk scores were lower than those at-80℃.During the experimental analysis,the centrifugal column method was superior to Trizol LS when extracting miRNA from plasma,and the recovery rate was the highest when the plasma volume was 200ul and 300ul.The difference in detection of miRNAs mainly came from the miRNA extraction step,and mainly the organic extraction step,while the reverse transcription and PCR had little effect on the miRNA quantification.The selected 8healthy subjects and 8 patients with myocardial infarction further verified the above results and found the difference reduced by internal reference calibration,but increased by external reference calibration.The 37 plasma risk scores were normally distributed with an average of-3.75 and a standard deviation of 3.138.Conclusion The expression of plasma miR-92a and miR-126 is decreased in patients with AMI,which may be related to myocardial injury and atherosclerosis.The AMI risk assessment model can predict AMI more accurately.miR-92a and miR-126 can provide a reference for the clinical diagnosis and prediction of AMI.When detecting miRNAs,strict adherencing to standard operating procedures for sampling,detection,and analysis can find and reduce non-specific fluctuations in the detection process.A preliminary exploration of miRNA detection standardization can provide a reference for clinical blood testing of miRNAs.