Platelet Reactivity After CABG

Study Overview
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Brief Summary
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Patients who have a heart attack are regularly treated with either clopidogrel or ticagrelor. In a large clinical trial, treatment with ticagrelor before coronary bypass surgery (CABG) was associated with a lower risk of death than treatment with clopidogrel. The reason for this difference cannot be explained on the basis of the study. One possible explanation is that the reversible binding of ticagrelor is advantageous because when new platelets are released, they are inhibited by the drug. Because clopidogrel binds irreversibly it cannot redistribute. The investigators will recruit patients who are scheduled for surgery after an acute coronary syndrome who have been treated with either ticagrelor or clopidogrel. After the patient provides informed consent, the investigators will review their medical record,record information and on the day after surgery the investigators will take one sample of blood. That blood will be analyzed for evidence of platelet activation (platelet microparticles, and platelet-leukocyte aggregates), the reactivity of young platelets, and the concentration of inflammatory cytokines. The investigators hypothesize that the evidence of platelet activation (platelet microparticles and platelet-leukocyte aggregates) and the reactivity of young platelets will be less in patients who have been treated previously with ticagrelor.

Official Title
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Platelet Activation, Reactivity, and Inflammation After Coronary Bypass Surgery In Patients Treated With Ticagrelor or Clopidogrel

Conditions
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Acute Coronary Syndrome

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Acute coronary syndrome, CABG, within 48 hours of last dose of clopidogrel or ticagrelor, treatment with aspirin Exclusion Criteria: Treatment with an antiplatelet agent other than aspirin, clopidogrel, or ticagrelor, Acute or chronic hematologic disorder including a preoperative Hgb less than 10 g/dl or platelet count less than 100,000/mm3, Moderate or severe renal insufficiency (glomerular filtration rate less than 60 ml/min), Active infection, Active malignancy, Unable/unwilling to provide informed consent

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| clopidogrel<br>previous treatment with clopidogrel | |
| ticagrelor<br>previous treatment with ticagrelor | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| reactivity of juvenile platelets | We will use flow cytometry to identify juvenile platelets and assess their likelihood to activate in response to a submaximal concentration of agonist. | 16-24 hours after CABG | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| platelet-leukocyte aggregates | We will identify the prevalence of platelet-leukocyte aggregates - a marker of platelet activation in vivo | 16-24 hours after CABG | 
| platelet microparticles | We will quantify the prevalence of platelet microparticles, reflecting platelet activation in vivo | 16-24 hours after CABG | 
| cytokine/chemokine array | We will quantify the concentration of common cytokines and chemokines. | 16-24 hours after CABG | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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ticagrelor, Coronary artery bypass surgery, platelet function, receptor binding, platelet reactivity, reversible binding