Background: Significant myocardial injury during cardiac surgery is associated with a 10-fold increase in 2-year complication rates, yet there remains no clinical gold standard for diagnosis. Troponin I has complete cardiospecificity and is clinically used for diagnosis of myocardial infarction in other settings.
Methods and results: One hundred consecutive patients undergoing open heart surgery (71 coronary artery bypass grafts and 29 aortic valve replacements) were enrolled and blood samples were drawn preoperatively, at 5 AM and 5 PM on days 1 and 2 after surgery, and at 5 AM for 3 more days. Twelve-lead electrocardiograms were performed daily and echocardiographic studies were performed on patients with either; electrocardiographic changes signifying likely myocardial damage, intraoperative complications, or elevated creatine kinase subfraction MB or troponin values. Seventeen patients had either new wall motion abnormalities or new Q waves all with peak cardiac troponin I >40 ng/mL. Stratification of patients by peak troponin values <40 and >60 ng/mL was highly predictive (P <.001) of days in intensive care unit, days on ventilator, development of new arrhythmia, and especially cardiac events. These postoperative variables also showed a stronger correlation with peak cardiac troponin I than did peak creatine kinase subfraction MB.
Conclusion: Peak troponin I values detect myocardial infarction the day after heart surgery and predicts patient outcome.