OBJECTIVE Perioperative myocardial infarction (PMI) is one of the most common causes of prolonged intensive care unit (ICU) and hospital stay after coronary artery bypass grafting (CABG) and is associated with poor prognosis and increases postoperative mortality due to the lack of accurate diagnostic methods. This study examines the association between electrocardiography (ECG) ischemic changes and cardiac troponin I concentration. METHODS In this cross-sectional study, the ECG of 100 patients was recorded before and 24 h after the surgery. The cardiac troponin I concentration was measured 24 h after the termination of the surgery. RESULTS The average concentration of troponin I was 6.79 μg/L in the no-ECG-changes group, 11.69 μg/L in the ST depression group, 11.26 μg/L in the ST elevation group, and 27.54 μg/L in the new Q wave group. The mean troponin concentration was significantly higher in the ECG-changes group compared to no-ECG-changes group. Comparing the ECG-changes together showed significant differences between the new Q wave and the other changes. ST elevation and ST depression were not statistically significant. CONCLUSIONS The three ECG-changes groups had a higher risk of PMI after their CABG. The risk of PMI was at its highest value in the new Q wave group and at its lowest in the no-ECG-changes group.