ABSTRACT: BACKGROUND: To compare postoperative cardiac troponin I (cTnI) release and the thresholds of cTnI that predict adverse outcome after elective coronary artery bypass graft (CABG), valve, and combined cardiac surgery. METHODS: Six hundred and seventy five adult patients undergoing conventional cardiac surgery with cardiopulmonary bypass were retrospectively analyzed. Patients in the CABG (n=225) and valve surgery groups (n=225) were selected after matching (age, sex) with those in the combined surgery group (n=225). cTnI was measured preoperatively and 24 h after the end of surgery. The main endpoint was a severe postoperative cardiac event (sustained ventricular arrhythmias requiring treatment, need for inotropic support or intra-aortic balloon pump for at least 24 h, postoperative myocardial infarction) and/or death. Data are medians and odds ratio [95% confidence interval]. RESULTS: Postoperative cTnI levels were significantly different among the three groups (Combined 11.0 [9.5-13.1] vs. CABG 5.2 [4.7-5.7] and Valve 7.8 [7.6-8.0] ng.mL-1, respectively, P<0.05). The thresholds of cTnI predicting severe cardiac event and/or death were also significantly different among the three groups (Combined 11.8 [11.5-14.8] vs. CABG 7.8 [6.7-8.8] and Valve 9.3 [8.0-14.0] ng.mL-1 respectively, P<0.05 level). An elevated cTnI above the threshold in each group was significantly associated with severe cardiac event and/or death (odds ratio, 4.33 [2.82-6.64]). CONCLUSIONS: The magnitude of postoperative cTnI release is related to the type of cardiac surgical procedure. Different thresholds of cTnI must be considered according to the procedure type to predict early an adverse postoperative outcome