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Cardiac troponin I predicts significant myocardial injury after bypass surgery

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Cardiac troponin-I is superior to electrocardiogram and creatinine kinase MB for predicting myocardial injury after coronary artery bypass graft (CABG) surgery, results of a new study indicate.

Dr. Jochen D. Muehlschlegel, of Brigham and Women’s Hospital, Harvard Medical School, Boston and colleagues investigated the diagnostic power of perioperative ECGs and the two cardiac biomarkers in predicting clinically relevant myocardial injury using benchmarks of mortality and increased hospital stay in 545 primary CABG patients.

“The key observations are that a diagnosis of perioperative myocardial injury or infarction by ECG after CABG does not predict extended hospital length of stay or postoperative mortality, our surrogate end-points for myocardial injury,” Dr. Muehlschlegel noted in an email to Reuters Health.

However, cardiac troponin-I levels on postoperative day 1 independently predicted 5-year mortality, with a hazard ratio of 1.42 for each 10 µg/L increase (p = 0.009), adjusted for baseline demographic and perioperative risk factors, the researchers report in the July issue of the European Heart Journal.

Cardiac troponin-I is a “more robust” predictor of mortality than creatinine kinase MB fraction, Dr. Muehlschlegel noted. “Moreover, the well-validated and commonly used logistic Euroscore is improved by the addition of cardiac troponin-I to predict mortality.”

However, measuring cardiac troponin-I after post-CABG day 1 provides “no incremental benefit when predicting 5-year mortality or hospital length of stay,” the researcher noted.

Dr. Muehlschlegel and colleagues confirmed the predictive value of cardiac troponin-I for 5-year mortality in a separate validation cohort of 1031 CABG patients.

“Together, these findings identify postoperative day 1 troponin as an important independent predictor of the clinical consequences of perioperative myocardial injury in patients undergoing CABG surgery,” Dr. Muehlschlegel concluded.

Euro Heart J 2009;30:1574-1583.