IN ELECTIVE CORONARY-ARTERY BYPASS-GRAFTING, PREOPERATIVE TROPONIN-T LEVEL PREDICTS THE RISK OF MYOCARDIAL-INFARCTION

Objective: Several combinations of risk factors for death or cardiac e vents after coronary artery bypass grafting have been described. We st udied the prognostic value of the preoperative serum levels of cardiac troponin T. Methods: We studied 468 patients who underwent elective c oronary artery bypass grafting, Preoperative and postoperative levels of cardiac troponin T and creatine kinase MB, electrocardiograms, clin ical data, and events were recorded prospectively. No acute ischemic c hanges were present on the electrocardiogram before the operations, an d preoperative creatine kinase MB serum levels were within normal limi ts in all patients. Results: Ninety-seven (97/468, 21%) patients had s erum levels of troponin T greater than 0.02 mu g/L within 24 hours bef ore coronary artery bypass grafting. Hospital mortality was similar in this group and in the patients with preoperative levels less than 0.0 2 mu g/L (1% in each group). Nine patients (9/97, 9%) with elevated le vels of troponin T before the operation had a perioperative myocardial infarction compared with 12 patients (12/371, 3%) among the group wit h lower troponin T levels (p = 0.015, RR = 2.9). Congestive heart fail ure occurred in 10 (10/97, 10%) and 8 (8/371,2%) patients, respectivel y (p = 0.0009, RR = 4.8), Intensive care unit (p = 0.002) and postoper ative hospital length of stay (p = 0.09) were all longer in patients w ith the elevated preoperative troponin T level. In a logistic regressi on analysis, troponin T level before the operation was the variable mo st strongly correlated with postoperative myocardial infarction (p = 0 .003), Conclusion: Preoperative troponin T stratification before coron ary artery bypass grafting identifies a subgroup of patients with incr eased risk of postoperative cardiac complications.