Aspirin and Clopidogrel Reactivity in Patients With Critical Limb Ischemia (CLI)

Study Overview
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Brief Summary
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Critical Limb Ischemia (CLI) is defined as limb pain that occurs at rest, or impending limb loss that is caused by severe compromise of blood flow to the affected extremity. CLI is a major cause of death and disability (secondary to myocardial infarction, stroke and amputation). The mortality in patients with CLI approaches 25% and 50% at one and five years respectively. High on-treatment platelet reactivity (HPR) in patients treated with aspirin and clopidogrel (previously referred to as resistance) is associated with an increased risk of recurrent cardiovascular events after percutaneous coronary interventions and acute coronary syndromes. The prevalence and significance of High on-treatment Platelet Reactivity (HPR) in patients with critical limb ischemia treated with aspirin and/or clopidogrel is not known. The investigators project aims to investigate the prevalence of HPR (to aspirin and clopidogrel) in one hundred patients with diagnosis of critical limb ischemia encountered at University of Southern California (USC) affiliated hospitals (Los Angeles County Hospital and Keck Hospital of University of Southern California).

Detailed Description
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This prospective clinical study will investigate the prevalence of high on- treatment platelet reactivity (HPR) in one hundred patients with critical limb ischemia (CLI), at the Keck Hospital of USC and Los Angeles County Medical Center (LAC+USC). Platelet inhibition to aspirin will be evaluated with the VerifyNow® aspirin (ASA) test. Clopidogrel platelet inhibition will be evaluated with two different tests: the vasodilator-stimulated phosphoprotein (VASP) and the VerifyNow® purigenic receptor P2Y12 (VN-P2Y12) assays. All platelet function analyses will be performed once after a minimum of one week of uninterrupted dual antiplatelet therapy with aspirin and clopidogrel. High on-treatment Platelet Reactivity on aspirin treatment (HPRA) group will be defined as aspirin reaction units (ARU) ≥550 by the VerifyNow® ASA assay. High on-treatment Platelet Reactivity on clopidogrel (HPRC) group will be defined as P2Y12 reaction units (PRU) ≥208 by the VerifyNow® assay and Vasodilator-stimulated phosphoprotein-platelet reactivity index (VASP-PRI) ≥50% by the vasodilator-stimulated phosphoprotein (VASP) assay. All other patients will be assigned to the adequate platelet reactivity on therapy (APR) group. Prevalence of high on-treatment platelet reactivity will then be calculated for aspirin and/or clopidogrel

Official Title
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Prevalence of High On-Treatment (Aspirin and Clopidogrel) Platelet Reactivity in Patients With Critical Limb Ischemia

Conditions
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Critical Limb Ischemia

Intervention / Treatment
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* Other: Blood draw only


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: EXPERIMENTAL GROUP: Patients with a diagnosis of critical limb ischemia (CLI) and uninterrupted treatment with aspirin and/or clopidogrel for at least one week before testing. CONTROL GROUP: 10 normal volunteers without any known co-morbidities Exclusion Criteria: Chronic use of nonsteroidal anti-inflammatory drugs, thrombocytopenia (platelet count <100 × 103/μl), use of an oral anticoagulant (warfarin), glycoprotein (GP) IIb/IIIa inhibitors, or fibrinolytic drugs within 30 days before testing. Any documented history of hypercoaguable states or history of medication non-compliance.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Single cohort<br>Single cohort will receive Blood draw only. | Other: Blood draw only<br>* Blood draw only<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Asses the Prevalence of High On-treatment Platelet Reactivity in Critical Limb Ischemia Patients Treated With Aspirin and Clopidogrel. | Platelet inhibition to aspirin will be evaluated with the VerifyNow® aspirin (ASA) test. Clopidogrel platelet inhibition will be evaluated with two different tests: the vasodilator-stimulated phosphoprotein (VASP) and the VerifyNow® purinergic receptor P2Y12 (VN-P2Y12) assays. | Single measurment after a minimum of one week of uninterrupted dual antiplatelet therapy with aspirin and clopidogrel | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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ASA-PLAVIX Reactivity in CLI