CK-MB release following coronary artery bypass grafting in the absence of myocardial infarction.

Elevation of levels of the myocardial-specific isoenzyme of creatine kinase (CK-MB) in the immediate postoperative period in patients undergoing coronary artery bypass grafting is usually associated with myocardial necrosis. However, mean isoenzyme elevations of 18 +/- 2 IU/L (standard error of the mean) were recently observed in 6 patients in the absence of electrocardiographic or scintigraphic (technetium 99m stannous pyrophosphate) evidence of perioperative myocardial infarction. To test the hypothesis that surgical trauma of the atrium and aorta during cannulation for cardiopulmonary bypass might contribute to elevated CK-MB levels, biopsy of the right atrial appendage and aorta of 7 patients was done at operation, the tissue samples were assayed for total creatine kinase (CK) activity using the Rosalki technique, and for CK-MB using column chromatography. The results indicate that the human atrium is a rich source of CK, with the proportion of CK-MB similar to that present in the ventricle (20%). In addition, technical considerations inherent in the performance of coronary bypass surgery may result in release of CK-MB, causing elevated serum enzyme levels in the post-coronary artery bypass patient in the absence of myocardial infarction.