Diagnostic accuracy of myoglobin concentration for the early diagnosis of acute myocardial infarction.
OBJECTIVE
We evaluated the diagnostic accuracy of myoglobin determination for the early diagnosis of acute myocardial infarction (AMI).


METHODS
Consecutive patients with chest pain were included in the study. Receiver operating characteristic (ROC) analysis was used to assess optimal timing of blood sampling and cutoff values.


RESULTS
A total of 309 patients were included, of whom 162 patients had a diagnosis of AMI. ROC analysis revealed that the diagnostic accuracy of myoglobin concentration as indicated by the area under the ROC curve (AUC) increased significantly from 3 (0.89+/-0.026) and 4 hours (0.93+/-0.019) to 5 hours after onset of symptoms (0. 96+/-0.014; P=.0040 and.035, respectively). At 5 hours (the earliest time point with maximal AUC), sensitivity was 87% and specificity was 97% using a myoglobin cutoff value of 90 microg/L. With a myoglobin cutoff value of 50 microg/L, sensitivity was 95% (95% confidence interval 90% to 98%), but specificity was 86% (95% confidence interval 80% to 93%).


CONCLUSIONS
Myoglobin has maximal diagnostic accuracy for the diagnosis of AMI at 5 hours after the onset of symptoms, using a cutoff value of 50 microg/L. In combination with the measurement of other biochemical markers, myoglobin determination could be particularly useful for triage of patients with AMI at an early stage.
de Winter
R J
RJ
Departments of Cardiology, Clinical Epidemiology and Biostatistics, and Clinical Chemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. r.j.dewinter@amc.uva.nl
Lijmer
J G
JG
Koster
R W
RW
Hoek
F J
FJ
Sanders
G T
GT
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D004796:Clinical Enzyme Tests; D016001:Confidence Intervals; D003402:Creatine Kinase / Q000097:blood; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D007120:Immunochemistry; D007124:Immunoenzyme Techniques; D007527:Isoenzymes; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis*; D009211:Myoglobin / Q000097:blood*; D009391:Nephelometry and Turbidimetry / Q000379:methods; D012372:ROC Curve; D012680:Sensitivity and Specificity; D013997:Time Factors; D020107:Troponin T / Q000097:blood
D007527:Isoenzymes; D009211:Myoglobin; D020107:Troponin T; D003402:Creatine Kinase