Troponin is superior to electrocardiogram and creatinine kinase MB for predicting clinically significant myocardial injury after coronary artery bypass grafting

• Published in: European heart journal 2009-07, Vol.30 (13), p.1574-1583
• Main Authors: Muehlschlegel, Jochen D., Perry, Tjörvi E., Liu, Kuang-Yu, Nascimben, Luigino, Fox, Amanda A., Collard, Charles D., Avery, Edwin G., Aranki, Sary F., D’Ambra, Michael N., Shernan, Stanton K., Body, Simon C.
• Format: Article
• Language: English
• Subjects: Aged; Biological and medical sciences; Biomarkers - blood; Cardiology. Vascular system; Cardiopulmonary bypass; Clinical Enzyme Tests; Clinical Research; Coronary Artery Bypass - adverse effects; Coronary heart disease; Creatine Kinase, MB Form - blood; Electrocardiography; Electrocardiography - methods; Enzymes; Epidemiologic Methods; Female; Heart; Humans; Length of Stay - statistics & numerical data; Male; Medical sciences; Middle Aged; Mortality; Myocardial Infarction - diagnosis; Myocardial Infarction - etiology; Myocarditis. Cardiomyopathies; Surgery; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Surgery of the heart; Troponin; Troponin I - blood
• ISSN: 0195-668X; 1522-9645
• DOI: 10.1093/eurheartj/ehp134

Aims Cardiac biomarkers are routinely elevated after uncomplicated cardiac surgery to levels considered diagnostic of myocardial infarction in ambulatory populations. We investigated the diagnostic power of electrocardiogram (ECG) and cardiac biomarker criteria to predict clinically relevant myocardial injury using benchmarks of mortality and increased hospital length of stay (HLOS) in patients undergoing coronary artery bypass graft (CABG) surgery. Methods and results Perioperative ECGs, creatinine kinase MB fraction, and cardiac troponin I (cTnI) were assessed in 545 primary CABG patients. None of the ECG criteria for myocardial injury predicted mortality or HLOS. However, post-operative day (POD) 1 cTnI levels independently predicted 5-year mortality (hazard ratio = 1.42; 95% CI 1.14–1.76 for each 10 µg/L increase; P = 0.009), while adjusting for baseline demographic characteristics and perioperative risk factors. Moreover, cTnI was the only biomarker that significantly improved the prediction of 5-year mortality estimated by the logistic Euroscore (P = 0.02). Furthermore, the predictive value of cTnI for 5-year mortality was replicated in a separately collected cohort of 1031 CABG patients using cardiac troponin T. Conclusion Electrocardiogram diagnosis of post-operative myocardial injury after CABG does not independently predict an increased risk of 5-year mortality or HLOS. Conversely, cTnI is independently associated with an increased risk of mortality and prolonged HLOS.