Aspirin Resistance and Stroke Risk: Platelet Function Analysis in Patients With Ischemic Events

Study Overview
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Brief Summary
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The purpose of this study is to determine if PFA results correlate with ischemic event outcomes as well as bleeding complications. Hypothesis is antiplatelet agents will be more efficacious if they are administered in a dose-adjusted manner using PFA results as a guide.

Detailed Description
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Atherothrombotic disease is a leading killer of adults throughout the world. The current mainstay for the prevention of ischemic vascular events is the use of aspirin Antiplatelet agents are used routinely for the primary and secondary prevention of vascular events in patients with a prior history of stroke, TIA, or at high risk for the development of cerebrovascular disease. Numberous individual studies and meta-analyses have shown that essentially all of the oral antiplatelet agents have limited efficacy, with relative risk reductions in the range of 20-35%. The purpose of this study is to perform serial platelet function assays (PFAs) on patients with cerebrovascular disease who are taking antiplatelet agents and perform a pilot study to determine the feasibility of administering ASA as a dose adjusted medication using PFA. The long term goal of this study is to determine whether antiplatelet therapy will be more efficacious and/or safer if it is administered in a dose-adjusted manner.

Official Title
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Multiphase Study to Determine if Platelet Function Analysis Results Correlate With Ischemic Events and Bleeding Complications

Conditions
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Stroke, Myocardial Infarctions

Intervention / Treatment
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* Drug: Clopidogrel
* Drug: Aspirin 81 mg
* Drug: Aspirin >300 mg


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patient must be taking Aspirin or Plavix Patient must have had a stroke, TIA or cerebrovascular disease Exclusion Criteria: -None

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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Design Details

Primary Purpose: Treatment
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Clopidogrel 75 mg<br>Clopidogrel 75 mg daily | Drug: Clopidogrel<br>* Clopidogrel 75 mg QD<br>* Other names: Plavix;|
| Active Comparator: Aspirin 81 mg<br>open-label Aspirin 81 mg daily | Drug: Aspirin 81 mg<br>* Aspirin 81mg QD<br>* Other names: ASA;|
| Active Comparator: Aspirin > 300mg<br>open-label Aspirin over 300 mg daily | Drug: Aspirin >300 mg<br>* Aspirin >300 mg QD<br>* Other names: ASA;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| PFA1 | Platelet Function Analysis (PFA) lab results: PFA was performed using the PFA 100 device (Dade-Behring), which uses a higher sheer stress flow cytometry paradigm to measure the time in seconds to closing of an aperture. Normal is defined as <172 seconds. | 3-6 months (Collected once between regulalary scheduled follow-up visit between 3-6 months) |