Objective To investigate the diagnostic and prognostic value of serum exosomal exocirc_0023461 in coronary artery disease(CAD)related acute myocardial infarction(AMI).Methods From December 2019 to January 2022,383 patients with CAD related AMI(AMI group),200 pa-tients with chronic stable CAD but no AMI(control group),and 200 healthy individuals identified with physical examination(healthy group)were recruited in our hospital.The serum exocirc_0023461 level was determined by real-time quantitative fluorescence polymerase chain reaction.The correlation of serum exosomal circ_0023461 level with clinicopathological features and oxida-tive stress indicators was analyzed.Results The serum level of exocirc_0023461 was significantly higher in the AMI group than the control group and healthy group[3.54(1.39,9.82)vs 0.86(0.62,1.23)and 0.65(0.41,0.79),P＜0.01].ROC curve analysis showed that when the serum level of exocirc_0023461 ≥1.31,its AUC value for the diagnosis of AMI was 0.857(95％CI:0.827-0.887),with a sensitivity and specificity of 78.90％and 83.50％,respectively.Kaplan-Meier survival curve displayed that the survival time was significantly shorter in the high level AMI patients without MACE than those with low level(X2=19.390,Plog rank＜0.01).Multivariate Cox regression analysis revealed that age,peripheral artery disease and serum exocirc_0023461 were independent predictors of MACE occurrence in AMI patients during follow-up(P＜0.05,P＜0.01).Pearson correlation analysis indicated that serum exocirc_0023461 level was negatively correlated with serum GPX and SOD levels(r=-0.395,r=-0.193,P＜0.01),and positively correlated with serum MDA level(r=0.194,P＜0.01).Conclusion Serum exocirc_0023461 may be a potential biomarker for the diagnosis and prognosis of CAD-related AMI,and its mechanism seems to be associated with its regulating oxidative stress and thus affecting myocardial injury.