[Diagnostic value of the myocardium-specific isoenzyme creatinephosphokinase (CK-MB)]

In 150 ambulatory and 155 hospitalized patients the normal values for creatine phosphokinase (CK) and the isoenzyme CK-MB were determined using a simple test with inhibiting antibodies. In a series of 100 consecutive patients hospitalized for chest pain, CK-MB was measured over a 72-hour period in 6- to 12-hourly intervals. The results were compared to the clinical findings, ECG, total CK and SGOT. In addition, CK-MB was determined after elective DC countershock and intramuscular injections (12 patients in each group). Normal values for CK-MB were found to be less than or equal to 10 U/1 in all patients, whereas the values for total CK turned out to be male less than 125 U/1, female less than 100 U/1 in ambulatory patients and less than 50 U/1 in hospitalized patients. In 68 of the 100 patients hospitalized for chest pain, acute myocardial infarction was found. The specificity of CK-MB in patients with transmural infarction was calculated as 100%, and the sensitivity as 97%. After DC countershock and intramuscular injections, CK was markedly elevated whereas CK-MB only rose after cardioversion. We conclude that CK-MB may be of considerable value for the differential diagnosis of elevated total CK activities of unknown origin. It is a very specific and a sensitive parameter for the diagnosis and exclusion of acute myocardial infarction.