How to correct high Maximum Amplitude (MA) on Thromboelastography (TEG)?

Correcting High Maximum Amplitude (MA) on Thromboelastography (TEG)

To correct high Maximum Amplitude (MA) on TEG, administer antiplatelet agents such as aspirin or P2Y12 inhibitors, as high MA indicates hypercoagulability which increases thrombotic risk. 1

Understanding High MA on TEG

• Maximum Amplitude (MA) represents the maximum strength of the clot and primarily reflects platelet function and fibrinogen concentration 1
• Normal MA values typically range from 50-70 mm, with values >70 mm indicating hypercoagulability 1
• Increased MA suggests enhanced platelet function, elevated fibrinogen levels, or other factors contributing to hypercoagulability 1
• High MA is associated with increased risk of thromboembolic events, as demonstrated in multiple clinical settings 2, 3

Diagnostic Approach

• Confirm hypercoagulability by evaluating other TEG parameters (shortened R time, increased alpha angle) that may accompany high MA 1
• Consider concurrent laboratory tests (platelet count, fibrinogen level) to better characterize the hypercoagulable state 1
• Rule out technical factors that might falsely elevate MA readings, such as sample handling errors or device calibration issues 1

Treatment Algorithm for High MA

1. First-line therapy: Antiplatelet agents

   • Administer aspirin (81-325 mg daily) as initial therapy 2
   • For higher risk patients or inadequate response to aspirin, consider adding P2Y12 inhibitors (clopidogrel, ticagrelor) 2

2. For severe hypercoagulability or high thrombotic risk:

   • Consider therapeutic anticoagulation with low molecular weight heparin (LMWH) or unfractionated heparin (UFH) 4
   • For pregnant patients with hypercoagulability, LMWH is preferred over UFH due to better safety profile 4

3. For specific clinical scenarios:

   • In cardiac surgery patients with high MA, dual antiplatelet therapy may be considered, though evidence for improved graft patency is limited 2
   • In trauma patients with hypercoagulability, early antiplatelet therapy should be considered to prevent thromboembolic complications 3

Monitoring Response

• Repeat TEG 12-24 hours after intervention to assess response 1
• Target MA normalization (typically <70 mm) 1
• Monitor for signs of bleeding after intervention, especially with combination antiplatelet therapy 2

Special Considerations

• Pregnancy naturally induces a hypercoagulable state with increased MA values, which may not require correction unless extremely elevated 4
• In liver disease, viscoelastic tests like TEG provide more valuable information than standard coagulation tests, but interpretation requires careful consideration of the clinical context 4
• Standard TEG has limited sensitivity to antiplatelet agents, so platelet mapping assays may be needed to accurately assess the effect of antiplatelet therapy 5

Pitfalls to Avoid

• Anemia can paradoxically show hypercoagulable TEG results due to decreased blood viscosity, potentially exaggerating the MA value 4
• TEG shows high coefficients of variance (7.1-39.9% for TEG parameters), so results should be interpreted with caution and in clinical context 4
• Results vary between devices and are not interchangeable between TEG and ROTEM systems 4
• Do not rely solely on MA without considering other TEG parameters and the overall clinical picture 1
• Remember that TEG is performed at 37°C and cannot assess effects of hypothermia on coagulation 4