European Heart Journal Advance Access originally published online on April 30, 2009
European Heart Journal 2009 30(13):1574-1583; doi:10.1093/eurheartj/ehp134
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Troponin is superior to electrocardiogram and creatinine kinase MB for predicting clinically significant myocardial injury after coronary artery bypass grafting
1 Department of Anaesthesiology, Perioperative and Pain Medicine, CWN L1, Brigham and Women’s Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA
2 Baylor College of Medicine, Division of Cardiovascular Anaesthesia at the Texas Heart Institute, St Luke’s Episcopal Hospital, Houston, TX, USA
3 Division of Cardiac Anaesthesia, Department of Anaesthesia and Critical Care, Massachusetts General Hospital Heart Center, Harvard Medical School, Boston, MA, USA
4 Division of Cardiac Surgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
Received 30 January 2009; accepted 12 March 2009; online publish-ahead-of-print 30 April 2009.
* Corresponding author. Tel: +1 617 525 8156, Fax: +1 617 730 2813, Email: jmuehlschlegel{at}partners.org
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.
Key Words: Cardiopulmonary bypass • Electrocardiography • Surgery • Mortality • Enzymes • Troponin
S.K.S. and S.C.B. contributed equally to the study. CABG Genomics Research Study; http://clinicaltrials.gov/show/NCT00281164