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Cardiac Markers and Chest Pain Diagnosis
The First Minutes in the ED
The initial evaluation of patients who present with chest pain usually involves four steps:
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Medical history, including relevant risk factors for coronary artery disease |
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Physical examination |
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12-lead electrocardiogram (ECG) |
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Blood tests, including cardiac markers |
Current American College of Cardiology/American Heart Association Guidelines1 and the National Academy of Clinical Biochemistry Standards2 recommend an ED protocol that yields an examination and ECG within 10 minutes and cardiac markers within 30 minutes. For more information, click to view the Practice Guidelines page.
The Important Role of Cardiac Markers
Cardiac markers can help detect injury to the myocardium. Markers are enzymes or proteins that are released into the blood in response to ischemia. According to ACC/AHA Guidelines,1 the ideal cardiac marker is present in high concentration in the myocardium, appears soon after onset of ischemia and should be absent from nonmyocardial tissue and blood.
The National Academy of Clinical Biochemistry (NACB)2 has noted that:
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The laboratory should perform STAT cardiac marker testing on a continuous random-access basis, with a target turnaround time (TAT) of one hour or less. The TAT is defined as the time from blood collection to the reporting of results. |
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Institutions that cannot consistently deliver cardiac marker TATs of approximately one hour should implement Point-of-Care (POC) testing devices. The cutoff concentrations of these devices should be set at the 99% upper reference limits3 so that the devices can detect the first presence of true myocardial injury. |
Important cardiac markers include:
Myoglobin
CK-MB
Cardiac Troponin I
High Sensitivity C- Reactive Protein
NT-proBNP
References |
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