Thromboelastography With Platelet Mapping to Guide Antiplatelet Therapy After Lower Extremity Revascularization
brief summary
The goal of this clinical trial is to learn if a blood clotting test called thromboelastography with platelet mapping (TEG-PM) can guide blood-thinning medication decisions in adults 18 years and older with peripheral artery disease (PAD) who have undergone leg artery open or endovascular surgery. The main questions it aims to answer are: * Can TEG-PM results improve blood-thinning medication levels in participants at high risk for blood clots after surgery? * Can adjusting blood-thinning medications based on TEG-PM results lower the rate of blood clots forming in their revascularized leg after surgery? Participants will: * Have blood samples taken before surgery and at 1 week, 1 month, 2 months, 3 months, 6 months, and up to 9 months after surgery * Have blood-thinning medications (aspirin, clopidogrel, and/or ticagrelor) adjusted based on TEG-PM results during the first 3 months after surgery * Have one additional blood test to check if clopidogrel is working properly * Have their medical records reviewed for 6 months after their last visit to check on their health outcomes
detailed description
Background and Scientific Rationale:
Peripheral artery disease (PAD) frequently requires lower extremity revascularization via bypass surgery or endovascular stenting. Despite standard antiplatelet therapy, thrombosis occurs in up to 17% of patients within 6 months of revascularization. Current thromboprophylaxis strategies apply a uniform approach that fails to account for substantial interpatient variability in platelet response, including the fact that 60-65% of patients exhibit partial or complete resistance to aspirin or clopidogrel.
Thromboelastography with platelet mapping (TEG-PM) is a viscoelastic point-of-care test that provides a comprehensive assessment of the coagulation cascade, including clot initiation, kinetics, strength, fibrinolysis, and platelet function. TEG-PM measures adenosine diphosphate (ADP)-mediated platelet inhibition, reflecting P2Y12 pathway activity and clopidogrel effect, and arachidonic acid (AA)-mediated platelet inhibition, reflecting cyclooxygenase pathway activity and aspirin effect.
Prior prospective observational work by this group in 82 patients demonstrated that TEG-PM can identify individualized mechanisms of hypercoagulability prior to thrombotic events, providing a clinically actionable window for intervention. Patients who experienced thrombotic events showed significantly lower platelet inhibition and higher platelet aggregation than those who did not thrombose. Preliminary analysis identified platelet aggregation greater than 70.8% and platelet inhibition below 27.5% as associated with thrombosis with 85% sensitivity. The optimal cutoff for ADP maximum amplitude (MA) indicating higher thrombosis risk was greater than 42mm with 82% sensitivity.
TEG-Guided Antiplatelet Protocol:
This study implements a step-up approach to antiplatelet therapy guided by serial TEG-PM results using the following prespecified thresholds:
* Platelet inhibition not greater than 30% AND platelet aggregation not less than 70% = high risk → therapy escalation * ADP MA not less than 42mm = high risk → therapy escalation * Values within therapeutic range → continue current regimen
Escalation follows this stepwise sequence:
1. Aspirin monotherapy (81 mg daily) 2. Dual antiplatelet therapy (DAPT) with aspirin and clopidogrel (75 mg daily) 3. DAPT with aspirin and ticagrelor (90 mg twice daily) replacing clopidogrel 4. Triple antiplatelet therapy (aspirin, clopidogrel, and ticagrelor) if platelet activity goals still not met
official title
The Use of Thromboelastography With Platelet Mapping to Guide Thromboprophylaxis Following Lower Extremity Revascularization for Peripheral Artery Disease