Analytical and clinical evaluation of creatine kinase MB mass assay by IMx: comparison with MB isoenzyme activity and serum myoglobin for early diagnosis of myocardial infarction.
We analytically and clinically evaluated Abbott's IMx assay for creatine kinase (CK) isoenzyme MB (CK-MB) in serum. Over a 1-year period, the method was more specific but less precise than catalytic isoenzyme measurements by electrophoresis or immunoinhibition. Sera from different individuals without electrophoretic evidence of CK-MB but containing macro CK type 1 (n = 20), mitochondrial CK (n = 5), or CK-BB (n = 5) were scored as CK-MB negative by the IMx. Likewise, CK-MB-negative by the sera remained so after addition of purified human CK-MM (< or = 7600 U/L) or CK-BB (< or = 8100 U/L). For 39 patients admitted for suspicion of uncomplicated acute myocardial infarction (precordial pain for < or = 4 h), the diagnostic performance of the IMx CK-MB assay on admission and 4 h later was superior to that of total CK activity and compared well with that of CK-MB activity measured by electrophoresis or immunoinhibition. An admission, myoglobin showed a higher diagnostic sensitivity, specificity, and predictive value than did CK-MB and was the most informative test. Diagnostic performance on admission and 4 h later was further improved by considering positivity for myoglobin and for CK-MB by IMx and for the change in each over the first 4 h of hospitalization as criteria. Twelve hours after admission, diagnostic performance was further improved for all CK and CK-MB methods but began to decline for myoglobin.
Van Blerk
M
M
Department of Clinical Chemistry, Academic Hospital and Medical School, Vrije Universiteit Brussel, Belgium.
Maes
V
V
Huyghens
L
L
Derde
M P
MP
Meert
R
R
Gorus
F K
FK
D000328:Adult; D000368:Aged; D003402:Creatine Kinase / Q000097:blood*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques / Q000592:standards* / Q000706:statistics & numerical data; D007527:Isoenzymes; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis / Q000201:enzymology*; D009211:Myoglobin / Q000097:blood*; D011933:Reagent Kits, Diagnostic / Q000592:standards* / Q000706:statistics & numerical data; D012189:Retrospective Studies
D007527:Isoenzymes; D009211:Myoglobin; D011933:Reagent Kits, Diagnostic; D003402:Creatine Kinase