Diagnostic value of serial measurement of cardiac markers in patients with chest pain:: Limited value of adding myoglobin to troponin I for exclusion of myocardial infarction

Background Despite improved laboratory assays for cardiac markers and a revised standard for definition of myocardial-infarction (AMI), early detection of coronary ischemia in unselected patients with chest pain remains a difficult challenge. Methods Rapid measurements of troponin I (Tnl), creatine kinase MB (CK-MB), and myoglobin were performed in 197 consecutive patients with chest pain and a nondiagnostic electrocardiogram for AML The early diagnostic performances of these markers and different multimarker strategies were evaluated and compared. Diagnosis of AMI was based on European Society of Cardiology/American College of Cardiology criteria. Results At a given specificity of 95%, Tnl yielded the highest sensitivity of all markers at all time points. A Tnl cutoff corresponding to the 10% coefficient of variation (0.1 mug/L) demonstrated a cumulative sensitivity of 93% with a corresponding specificity of 81% at 2 hours. The sensitivity was considerably higher compared to CK-MB and myoglobin, even considering patients with a short delay until admission. Using the 99th percentile of Tnl results as a cutoff (0.07 mug/L) produced a cumulative sensitivity of 98% at 2 hours, but its usefulness was limited due to low specificities. Multimarker strategies including Tnl and/or myoglobin did not provide a superior overall diagnostic performance compared to Tnl using the 0.\1 mug/L cutoff. Conclusion A Tnl cutoff corresponding to the 10% coefficient of variation was most appropriate for early diagnosis of AML A lower Tnl cutoff may be useful for very early exclusion of AML CK-MB and in particular myoglobin did not offer additional diagnostic value.