II. Indications
- Myocardial Infarction Evaluation
III. Protocol: Typical
- Troponin I or Troponin T at presentation and 3 hours later
- May extend Troponin Timing to every 4 to 6 hours for 3 samples
- Trend upward above discriminatory Troponin values suggests acute Myocardial Infarction
- Older protocols using CK and CK-MB have largely been replaced by Troponins
IV. Protocol: Troponin and CK-MB with 2 hour intervals (older protocol)
- Initial tests at presentation
- Troponin I or Ultrasensensitive Troponin T
- CK and CK-MB
- Tests at 2-4 hours after initial labs
- Troponin I
- CK and CK-MB
- Interpretation: Case in which acute Myocardial Infarction unlikely
- Initial Ultrasensitive Troponin T negative or
- Second Troponin I negative and CK-MB not increasing
- References
- Weingart in Majoewsky (2012) EM:RAP 12(4): 6-7
V. Protocol: Troponin and CK-MB every 8 hours for 3 samples (older protocol)
- Protocol
- Obtain Troponin at 0 hours, 8 hours and 16 hours
- Primary Cardiac Marker: Specific for cardiac event
- Not useful for monitoring event extension
- Levels stay elevated for 14 days
- Obtain CK-MB at 0 hours, 8 hours, and 16 hours
- Primary purpose: Follow cardiac event extension
- Decreases more rapidly than Troponin after event
- Obtain Troponin at 0 hours, 8 hours and 16 hours
-
Test Sensitivity of combined protocol
- Test Sensitivity: >98% at 8 hours
- Test Specificity: 80 to 95% at 8 hours
- References
VI. Labs: Troponin
- Rises: 3-6 hours (up to 10 hours)
- Peaks: 12-48 hours
- Duration: 4-10 days
- Subunits
VII. Labs: Creatine Phosphokinase (CPK)
VIII. Labs: Myoglobin
- Advantage: First Cardiac Marker to increase
- Disadvantage: Poor Specificity (only helps if negative)
- Rises: 1-2 hours
- Peaks: 4-6 hours
- Duration: 1-2 days
IX. Labs: Glutamic oxaloacetic transaminase (AST, SGOT)
- Peaks: 24-36 hours
- Duration: 5 days
X. Labs: Lactic Dehydrogenase (LDH)
- Peaks: 24-48 hours
- Duration: 14 days
XI. Labs: White Blood Cell Count
- Predicts adverse events in Unstable Angina
- Morbidity and mortality increase with increased WBCs
- References