TIME CHANGES OF CREATINE-KINASE AND CREATINE KINASE-MB ISOENZYME VERSUS DISCRIMINATION VALUES IN THE DIAGNOSIS OF ACUTE MYOCARDIAL-INFARCTION - WHAT IS THE OPTIMAL METHOD FOR DISPLAYING THE DATA

We wanted to determine the optimal method for displaying data for the clinical evaluation of patients with possible acute myocardial infarction. Our primary question was, are the time changes;(slopes) of the enzyme tests better predictors of disease than the discrimination values, i. e., the cut-off points? We studied 152 patients with and 114 without a diagnosis of acute myocardial infarction in their medical records. For patients with acute myocardial infarction, we found the most discriminating tests, in decreasing order of the area of the ROC curves, to be the creatine kinase-MB slope at 0 to 12 hours, the creatine kinase-MB slope at 12 to 24 hours, the creatine kinase-MB values between 12 and 24 hours, and the creatine kinase-MB values between 0 and 12 hours. Decreasing values of creatine kinase-MB in the first tests after admission were only slightly less discriminating than increasing ones. At 12 to 24 hours after admission, the total creatine kinase as a value or slope, or the ''relative index'' (a ratio of the creatine kinase-MB in mu g/l [times 100] to the total creatine kinase) as a value or slope were inferior to creatine kinase-MB presentations. From the data for 44 patients with acute myocardial infarction and a known time of onset of symptoms, we were able to estimate an approximate onset time in patients where this was not available. We recommend that changes in the creatine kinase-MB concentration with time and the values themselves should be displayed in all patients with suspected acute myocardial infarction, and that at least three specimens should be collected in the 24-h period after admission. Analog representation of the data along with calculated slopes facilitate the identification of patients with possible acute myocardial infarction. The creatine-kinase-MB test has clear limitations: several conditions have values or slopes that suggested infarction but are really something else.