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 tissue 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 sample proportions taken at 0-2 h from the onset of symptoms was myoglobin > CK-MB2 > CK-MB. At all other time points, the sensitivity of CK-MB2 either equaled or surpassed that of both CK-MB and myoglobin, although the 95% confidence intervals for the population proportions each of 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 myoglobin was statistically lower than that for either CK-MB2 or CK-MB at all time points.
Laurino
J P
JP
Department of Pathology and Laboratory Medicine, Memorial Hospital of Rhode Island, Pawtucket 02860, USA. JPLaurino@aol.com
Bender
E W
EW
Kessimian
N
N
Chang
J
J
Pelletier
T
T
Usategui
M
M
D000328:Adult; D000368:Aged; D003402:Creatine Kinase / Q000097:blood*; D004795:Enzyme Stability; D005260:Female; D015200:Fluoroimmunoassay; D006801:Humans; D007527:Isoenzymes; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000175:diagnosis*; D009211:Myoglobin / Q000032:analysis*; D012680:Sensitivity and Specificity
D007527:Isoenzymes; D009211:Myoglobin; D003402:Creatine Kinase