Objective:To investigate the value of myocardium scar area in predicting adverse cardiovascular events (MACEs) after coronary artery bypass grafting (CABG) in patients with ischemic cardiomyopathy (ICM).Methods:The first part of this study was a retrospective study. Patients diagnosed with ICM and undergoing CABG surgery at Beijing Anzhen Hospital, Capital Medical University from January 2017 to December 2022 were enrolled as the discovery cohort. All patients underwent cardiac magnetic resonance-late gadolinium enhancement (CMR-LGE) before surgery. According to the occurrence of postoperative MACEs, the patients were divided into MACEs group and MACEs-free group. Preoperative clinical and imaging data, intraoperative and postoperative data were collected and compared between the two groups. The primary endpoint was postoperative MACEs. Univariate and multifactor regression analyses were used to analyze the risk factors for MACEs. Receiver operating characteristic (ROC) curves were constructed to evaluate the predictive efficacy and optimal cut-off value of myocardial scar area for endpoint events. The second part of this study was a prospective study. Patients with ICM who received CABG at Beijing Anzhen Hospital, Capital Medical University from January 2023 to June 2023 were enrolled as a validation cohort, and were divided into MACEs group and MACEs-free group according to whether MACEs occurred after surgery. Preoperative clinical and imaging data, intraoperative and postoperative data were collected and compared between the two groups. Verify the reliability of the cut-off value obtained by ROC curve in the validation cohort.Results:A total of 120 patients with ICM (30 patients in MACEs group and 90 patients in MACEs-free group), aged (61.6±8.7) years, including 93 males, were included in the discovery cohort. A total of 22 ICM patients (5 patients in MACEs group and 17 patients in MACEs-free group), aged (59.5±8.2) years, including 18 males, were included in the validation cohort. Multivariate Cox regression showed that myocardial scar area ( HR=1.258, 95% CI 1.096-1.444, P=0.001) was an independent risk factor for the primary endpoint event. The area under ROC curve of myocardial scar area for predicting postoperative MACEs was 0.90 (95% CI 0.83-0.95), and myocardial scar area≥36.0% was the optimal cut-off value for predicting postoperative MACEs, and its sensitivity, specificity and accuracy were 96.7%, 72.2% and 78.3%, respectively. In the validation cohort, the sensitivity, specificity and accuracy of myocardial scar area in predicting postoperative MACEs in patients with ICM after CABG were 80.0%, 82.4% and 81.8%, respectively. Conclusion:Myocardial scar area is an independent risk factor for MACEs after CABG in patients with ICM, and myocardial scar area≥36.0% is the optimal cut-off value for predicting MACEs after CABG. Myocardial scar area can help to identify patients at high risk of surgery and provide a basis for risk stratification of patients.