[Is creatine kinase isoenzyme CK-MB a diagnostic tool for perioperative myocardial infarctions? (author's transl)].

There is still controversy of the validity of elevated CK-MB serum activity in the diagnosis of perioperative myocardial infarction after open heart surgery. CK-MB activity was investigated using myocardial and skeletal muscle biopsies and in sera postoperatively in 192 patients. In biopsies CK-MB fraction of total myocardial CPK was 37%, the total-CPK activity of human skeletal muscles still shows a 5% fraction of CK-MB. There has to be more than 8% CK-MB fraction of total CPK-serum-activity to take this as evidence of myocardial damage. 3 h postoperatively enzymatic-immunologic CK-MB test is no longer interfered by enzymes derived from hemolyzed erythrocytes. In patients without signs of myocardial lesions postoperatively mean CK-MB-activity is 11 to 27 U/1 depending on the operative procedure performed. Activity levels exceeding 50 U/1 are almost evident of myocardial infarction. Elevated CK-MB-serum activity is a sensitive parameter for myocardial lesions overestimating an event of infarction. It is a helpful tool diagnosing perioperative myocardial infarction.