Cardiac troponins are the preferred marker for evaluating chest pain. CK-MB should be used only when cardiac troponins are not available. The 2007 ESC/ACC/AHA guidelines recommend use of cardiac markers in the following manner:
Necrosis is present if:
- Elevations of cTnI or cTnT over the decision limit on one occasion in the first 24 hours after chest pain.
- Elevations of CK-MB (specified as mass measurement) over decision limit on two successive samples or one sample that is two times the upper limit of normal during the first hours following chest pain. The CK-MB levels should exhibit a rising or falling pattern to be diagnostic. If the CK-MB levels do not fall, it is likely not an AMI.
Healthcare facilities and cardiology staff will develop their own criteria for AMI diagnosis and treatment based on these guidelines.