What is the treatment for elevated ADP (Adenosine Diphosphate) inhibition as indicated by Thromboelastography (TEG)?

Treatment for Elevated ADP Inhibition on Thromboelastography (TEG)

For patients with elevated adenosine diphosphate (ADP) inhibition on thromboelastography, platelet transfusion is the recommended treatment to reverse platelet dysfunction and improve outcomes. 1

Understanding ADP Inhibition on TEG

Thromboelastography (TEG) with platelet mapping provides valuable information about platelet function, including the contribution of ADP receptors to clot formation. ADP receptor inhibition can occur due to:

• Pre-injury use of P2Y12 inhibitors (clopidogrel, prasugrel, ticagrelor)
• Traumatic brain injury (TBI) severity (higher severity correlates with greater inhibition) 2
• Certain medications like milrinone 3
• Natural variability (healthy individuals can show up to 58% ADP receptor inhibition) 4

Treatment Algorithm

1. Assess the Degree of ADP Inhibition

• Mild inhibition (<40%): May not require intervention unless active bleeding
• Moderate inhibition (40-60%): Consider intervention based on clinical context
• Severe inhibition (>60%): Strongly consider intervention, especially with active bleeding or before surgery 2

2. Determine the Cause

• Medication-induced:

  • P2Y12 inhibitors (clopidogrel, prasugrel, ticagrelor)
  • Phosphodiesterase inhibitors (milrinone)

• Trauma-induced:

  • TBI severity correlates with degree of platelet dysfunction 2, 5

3. Implement Treatment

Primary Treatment:

• Platelet transfusion: The cornerstone of treatment for elevated ADP inhibition 1, 5
  • Standard dose: 1 apheresis unit or 4-6 units of pooled platelets
  • May require repeat TEG to assess response

For Patients on P2Y12 Inhibitors:

• Timing considerations:
  • For clopidogrel: Discontinue 5-7 days before elective surgery 1
  • For prasugrel: Discontinue 7 days before elective surgery 1
  • For ticagrelor: Discontinue 3-5 days before elective surgery 1

For Emergency Surgery:

• Platelet transfusion is recommended when surgery cannot be delayed 1
• Consider haemadsorption filters if urgent cardiopulmonary bypass is needed in patients with P2Y12 inhibitors 1

Special Considerations

Traumatic Brain Injury

• Patients with TBI and ADP inhibition >60% have significantly higher mortality (32% vs 8%) 2
• Platelet transfusion may reduce ADP inhibition by approximately 15% in TBI patients 5
• Consider earlier intervention in TBI patients with elevated ADP inhibition

Cardiac Surgery

• For patients requiring emergency cardiac surgery while on P2Y12 inhibitors, consider:
  • Platelet transfusion
  • Haemadsorption filters during cardiopulmonary bypass 1

Monitoring Response

• Repeat TEG platelet mapping after intervention to assess effectiveness
• Target ADP inhibition <40% for optimal hemostasis

Pitfalls and Caveats

1. Variable response to platelet transfusion: Not all patients show significant improvement in ADP inhibition after transfusion 5

2. High baseline variability: Even healthy individuals can have ADP receptor inhibition up to 58%, making interpretation challenging 4

3. Timing matters: Platelet transfusion too early before surgery may be ineffective due to the short lifespan of transfused platelets

4. TEG variability: There is significant inter-center and inter-operator variability in TEG results, requiring standardized protocols 1, 6

5. Limited evidence: While TEG is widely used, some studies show conflicting results regarding clinical outcomes 6

By following this algorithm and understanding the limitations of both TEG interpretation and treatment options, clinicians can effectively manage patients with elevated ADP inhibition detected on thromboelastography.