Cardiac troponin I in perioperative myocardial infarction after coronary artery bypass surgery

BACKGROUND AND AIMS: Myocardial infarction after coronary artery bypass grafting is a serious complication and one of the most common causes of perioperative morbidity and mortality. The present study was designed to determine the relevance of serum cardiac troponin I as a specific diagnostic marker for perioperative myocardial infarction. METHODS: A cohort of 64 patients undergoing coronary artery bypass grafting was enrolled for prospective study. Postoperative blood samples were extracted and analyzed for total creatine kinase (CK), CKMB and cardiac troponin I activity. Perioperative infarction was defined as the development of new Q waves in the postoperative electrocardiogram together with congruent regional wall motion abnormalities in the echocardiogram and CK values greater than 400 IU/l with MB fraction greater than 40 IU/l. RESULTS: Perioperative infarction occurred in 12 patients. Higher cardiac troponin I values were observed in patients experiencing perioperative myocardial infarction than in those without infarction (p < 0.001). Cardiac troponin I values higher than 12 ng/ml 10 h after release of the aortic clamp best detected the presence of perioperative myocardial infarction, with an area under the characteristic receiver operating curve of 0.91 (95% CI, 0.82-0.97), a sensitivity of 90.9%, and a specificity of 88.5%.The mean stay in the intensive care unit was significantly longer for patients who suffered perioperative myocardial infarction (6.5 8.6 days) than for patients without perioperative infarction (4.7 7.5 days) (p < 0.005). CONCLUSIONS: Cardiac troponin I elevation appears to be an early, specific marker for the diagnosis of perioperative myocardial infarction after coronary artery bypass grafting.