Serum enzymes with special reference to CK-MB following coronary bypass surgery.

In a consecutive series of 25 coronary bypass operations, the postoperative serum activity levels of total creatine kinase (CK) and its more heart-specific isoenzyme CK-MB were examined and related to the levels of aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT) and thermostable lactate dehydrogenase (LD-T), to electrocardiographic (ECG) findings and to surgical characteristics. Detectable CK-MB activity was found in all patients, usually appearing while the operation was still in progress. Peak CK-MB occurred earlier than peak total CK. There was no ECG evidence of myocardial infarction in any patient. The degree of postoperative CK-MB elevation, however, correlated to the duration of extracorporeal circulation (ECC) and aortic cross-clamping (AC). After 120 min of ECC and 70 min of AC, release of CK-MB, as well as of the other enzymes studied, increased considerably. There was a significant correlation between high CK-MB activity and high early postoperative activities of total CK, ASAT and LD-T. When CK-MB determinations are not available, ASAT is preferable to total CK or LD-T in the early evaluation of operative myocardial injury. From the fourth postoperative day, only LD-T is informative in this respect; a second rise of ASAT and ALAT is probably of hepatic origin.