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Failure of new biochemical markers to exclude acute myocardial infarction at admission
A J Bakker1, M J Koelemay, J P Gorgels
1Department of Clinical Chemistry, Klinisch Chemisch Laboratorium, Leeuwarden, The Netherlands.
Insights
Newer cardiac biomarkers like troponin T show high sensitivity for myocardial infarction detection. However, all tested markers, including creatine kinase (CK) and myoglobin, had insufficient negative predictive values for early exclusion of heart attacks.
Area of Science:
- Cardiology
- Biochemistry
- Medical Diagnostics
Background:
- Electrocardiogram (ECG) is often inconclusive for diagnosing myocardial infarction (MI) in a significant patient subset.
- Biochemical markers are crucial for timely clinical decisions upon patient admission for suspected MI.
Purpose of the Study:
- To evaluate the diagnostic utility of novel cardiac markers (creatine kinase MB (CK-MB) mass, troponin T, myoglobin) for excluding MI at admission.
- To compare these newer markers against conventional markers (creatine kinase (CK), CK-MB activity).
Main Methods:
- A study involving 290 consecutive patients with suspected MI.
- Diagnosis of acute MI based on clinical history, ECG, and serial CK and CK-MB activity changes.
- Assessment of sensitivity, specificity, and predictive values of various biomarkers.
Main Results:
- Troponin T demonstrated the highest sensitivity (64%) for detecting acute MI.
- Creatine kinase MB (CK-MB) mass concentration showed the highest negative predictive value in patients admitted within 8-10 hours.
- All evaluated markers exhibited inadequate negative predictive values for excluding MI in patients presenting within 10 hours of symptom onset.
Conclusions:
- Troponin T is a highly sensitive marker for acute MI but also has a high false-positive rate.
- No single marker, including troponin T, allows for reliable exclusion of acute MI upon admission for patients with recent symptom onset (<10 hours).
- Further refinement of diagnostic strategies is needed for early MI detection and exclusion.
Abstract:
In a substantial proportion of patients with suspected myocardial infarction, biochemical markers are needed for clinical decision-making at the time of admission, because electrocardiographic (ECG) recordings are inconclusive. We have assessed the usefulness for exclusion of myocardial infarction at admission of the newer markers creatine kinase MB (CK-MB) mass concentration, troponin T, and myoglobin in comparison with the routinely used markers creatine kinase (CK) and CK-MB activity. 290 consecutive patients were enrolled. Acute myocardial infarction was diagnosed on the basis of clinical history, ECG criteria, and time-dependent changes in CK and CK-MB activity. 153 patients had definite acute myocardial infarction. Troponin T had the highest sensitivity for prediction of acute myocardial infarction; high concentrations (above the upper reference limits) were found in 98 (64%) of the patients with infarctions compared with 92 (60%) for CK-MB mass concentration, 76 (50%) for myoglobin, 61 (40%) for CK activity, and 53 (35%) for CK-MB activity. However, troponin T also had the highest "false-positive" rate; of 137 patients without myocardial infarction, 36 (26%) had high troponin T concentrations. Sensitivity, specificity, and positive and negative predictive values were calculated in relation to time between onset of chest pain and hospital admission. Although CK-MB mass concentration was, by a small margin, the best marker in patients admitted within 8-10 h of onset of chest pain, all the markers had negative predictive values too low to allow exclusion of acute myocardial infarction at admission in patients with symptoms suggestive of myocardial infarction of less than 10 h duration.