Serum Myoglobin, Creatine Kinase and Creatine Kinase-MB as Mutually Supportive Indices of Myocardial Infarction and Infarct Size*

Abstract

A comparison was made between the appearance of serum myoglobin and creatine kinase (CK) in 22 patients with acute myocardial infarction who were admitted to a coronary care unit within 4 h of onset of chest pain. The MB isoenzyme of creatine kinase (CK-MB) was measured in 12 patients. The more rapid appearance and disappearance of myoglobin relative to CK and CK-MB was confirmed, as was the correspondence between their respective peak values. A significant correlation was also obtained between the area under the myoglobin time-course and the respective peak levels. While creatine kinase activity declined exponentially from a single peak, myoglobin appeared in multiple episodes inadequately represented by a single peak value and having no clear clinical correlation. The role of myoglobin as a diagnostic aid in myocardial infarction is probably limited to its ability to support CK and CK-MB as indices of infarct size.