Usefulness of cardiac troponin I in patients undergoing open heart surgery

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.

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.

Peak troponin I values detect myocardial infarction the day after heart surgery and predicts patient outcome.