To calculate the cutoff value of cardiac troponin I for predicting major adverse cardiac events (MACEs) after coronary artery bypass grafting (CABG) and identify the risk factors for MACEs after CABG.

Two hundred patients who underwent CABG at Peking University People's Hospital from August 2020 to August 2021 were enrolled, and their clinical characteristics were collected. The patients were divided into a MACE group and a non-MACE group according to the occurrence of MACEs or not over a 12-day postoperative period. Clinical, laboratory, and outcome data were collected.

The 200 patients were classified into the MACE (n=15) and non-MACE (n=185) groups. Based on receiver operating characteristic curve analysis, the optimal joint hs-TnI, CK-MB, and MYO cut-off levels at 4~6 h after surgery for predicting postoperative MACEs were 4131.4 pg/ml, 24.9 ng/ml, and 316.5 ng/ml, respectively. The area under the curve of the thee indexes combined for predicting postoperative MACEs was 0.741 (95% confidence interval: 0.617~0.865, P=0.002), with a sensitivity of 53.3% and specificity of 85.9%. When the hs-TnI, CK-MB, and MYO levels exceeded the joint cut-off levels, the incidence of postoperative MACEs was significantly increased (Log rank P＜0.05). Cox regression analysis showed that hs-TnI level and CK-MB level were the main risk factors for MACEs after CABG (P＜0.05).

An hs-TnI level of 4131.4 pg/ml, CK-MB level of 24.9 ng/ml, and MYO level of 316.5 ng/ml are the cutoff values for predicting MACEs after coronary artery bypass grafting. Hs-TnI level and CK-MB level are the main risk factors for MACEs after CABG.