COMPARATIVE SENSITIVITIES AND SPECIFICITIES OF THE MASS MEASUREMENTS OF CK-MB2, CK-MB, AND MYOGLOBIN FOR DIAGNOSING ACUTE MYOCARDIAL-INFARCTION

We evaluated the clinical utility of the mass measurement of the tissu e isoform of creatine kinase MB isoenzyme (CK-MB2) in the diagnosis of an acute myocardial infarction (AMI) by determining its sensitivity, specificity, and predictive value relative to those of CK-MB mass and myoglobin, Samples were obtained at 0, 4, 8, and 16 h postpresentation from 100 patients (41% with AMI). The order of sensitivity for the sa mple proportions taken at 0-2 h from the onset of symptoms was myoglob in > CK-MB2 > CK-MB, At all other time points, the sensitivity of CK-M B2 either equaled or surpassed that-of both CK-MB and myoglobin, altho ugh the 95% confidence intervals for the population proportions each o f these markers overlapped, Of the 41 AMI patients, 31 (76%) exhibited concurrent abnormal increases of CK-MB and %CK-MB2; the other 10 (24% ; 8 non-Q wave, 2 Q wave) exhibited abnormal values for %CK-MB2 before their CK-MB exceeded the upper limit of normal, The specificity of my oglobin was statistically fewer than that for either CK-MB2 or CK-MB a t all time points.