• Level A recommendations. Do not utilize cardiac serum marker tests to exclude non-AMI acute coronary syndromes (i.e., unstable angina).
• Level B recommendations. Utilize any of the following cardiac serum marker tests to exclude non–ST-segment elevation AMI as denied by the World Health Organization (WHO) or modified WHO criteria.*
  1. A single negative CK-MB mass, Troponin I, or Troponin T measured 8 to 12† hours after symptom onset.‡
  2. A negative myoglobin in conjunction with a negative CK-MB mass, or negative Troponin§ when measured at baseline and 90 minutes in patients presenting less than 8 hours after symptom onset.‡
  3. A negative 2-hour delta CK-MB mass** in conjunction with a negative 2-hour delta Troponin§,** in patients presenting less than 8 hours after symptom onset.‡
• Level C recommendations. None specified.

* There is insufficient evidence at this time to make any recommendations in regard to utilization of cardiac serum markers to exclude non–ST-segment elevation AMI using current Joint European Society of Cardiology(ESC)/ACC criteria for AMI.

† The exact timing of serum marker measurement as it relates to time of symptom onset should take into account the sensitivity, precision, and institutional norms of the assay being utilized, as well as the release kinetics of the marker being measured.

‡ If time of symptom onset is unknown, unreliable, or more consistent with preinfarctional angina, then time of symptom onset should be referenced to the time of ED presentation.

§ Only Troponin I has been investigated in the serial 90 minute multimarker protocol and the 2-hour delta protocol.

** The appropriate delta values for exclusion of AMI should take into account the sensitivity and precision of the assay used and confirmed by in-house studies. It is also important that delta serum marker levels are measured on the same instrument due to subtle variations in calibration among individual instruments of the same model.