DEMONSTRATION OF ISCHEMIA-REPERFUSION INJURY SEPARATE FROM POSTOPERATIVE INFARCTION IN CORONARY-ARTERY BYPASS GRAFT PATIENTS

Background. In patients undergoing coronary artery bypass grafting the re are two possible causes of myocardial injury: (1) global ischemic m yocardial injury during aortic cross-clamping and subsequent reperfusi on, and (2) postoperative myocardial infarction. We studied the use of cardiac marker proteins to specifically and separately detect such in jury. Methods. Serum levels of enzymes (creatine kinase and creatine k inase-MB) and nonenzymatic proteins (fatty acid-binding protein and my oglobin) were measured in 8 low-risk patients undergoing coronary arte ry bypass grafting with cardiopulmonary bypass, 8 low-risk patients un dergoing coronary artery bypass grafting without cardiopulmonary bypas s, and 39 high-risk patients undergoing coronary artery bypass graftin g with cardiopulmonary bypass, of whom 7 experienced a postoperative m yocardial infarction. Results. At 0.5 hours after reperfusion signific antly increased plasma levels of all markers were noted in patients ha ving the operation with cardiopulmonary bypass, but not in patients ha ving the operation without cardiopulmonary bypass. In patients who had a postoperative myocardial infarction, a second significant increase of each marker was found, but that of fatty acid-binding protein was r ecorded 4 hours earlier than that of creatine kinase, creatine kinase- MB, or myoglobin. Conclusions. Perioperative myocardial injury can be diagnosed from the release of cardiac marker proteins into plasma alre ady at 0.5 hours after the start of reperfusion. For early assessment of postoperative myocardial infarction, fatty acid-binding protein is a more suitable plasma marker than are creatine kinase, creatine kinas e-MB, or myoglobin. (C) 1998 by The Society of Thoracic Surgeons.