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Platelet Function Assessment for Atherothrombotic Patients

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00513149
Recruitment Status : Unknown
Verified January 2011 by National Taiwan University Hospital.
Recruitment status was:  Recruiting
First Posted : August 8, 2007
Last Update Posted : January 24, 2011
Information provided by:
National Taiwan University Hospital

Brief Summary:
Background-Despite the pivotal pathogenic role of platelets in atherothrombosis has been widely recognized, there is a striking lack of consensus regarding how to measure platelet function and how to monitor the effects of various antiplatelet drugs. In view of the fact that recurrent ischemic events occurred in 8.5% to 8.8% of patients treated with dual antiplatelet drugs and there is significant inter-individual variability in platelet reactivity, we believe that the importance of platelet function assessment and its clinical implication should not be overlooked.

Condition or disease Intervention/treatment Phase
Coronary Artery Disease Drug: Clopidogrel Phase 4

Detailed Description:

Methods and Expected Results-In this prospective follow-up study, we will assess the predictive power of different assays of platelet function (PFA-100, plasma levels of von Willebrand factor, P-selectin, soluble CD40 ligand, and myeloid-related protein-8/14, and ADP-induced P-selectin [CD62P] expression on platelets by flow cytometry) before and after high-dose (600 mg) clopidogrel loading, at 3-month follow-up, and at study end on the occurrence of major cardiovascular events (MACE)(death, myocardial infarction, stroke, and coronary revascularization). We will also evaluate the correlations between different assays of platelet function. Based on our previous pilot study which demonstrated that a significant association between collagen-ADP closure time measured by PFA-100 and the occurrence of major cardiovascular events in 130 patients undergoing coronary angioplasty followed up for 6 months, we plan to include 150-200 patients into the present study. The total inclusion period is estimated to be 1 year. Therefore, a total of 2 to 2.5 years will be needed to complete this study. In the first year, we will analyze (1) the correlations between various platelet parameters and coronary angiographic findings; (2) the correlations among different platelet function measurements; and (3) the responsiveness of CADP-CT on high-dose clopidogrel loading.

In the second year, we will (1) analyze the predictability of various platelet parameters, at different point of time (baseline, after clopidogrel loading, at study end), on the occurrence of MACE and (2) establish a risk-prediction schema for patients undergoing coronary angioplasty. A pre-defined threshold value for the collagen-epinephrine closure time is set at 190 s, since this value has been recommended by other investigators to differentiate the presence or absence of aspirin resistance. A pre-defined threshold value for the collagen-ADP closure time is set at 90 s, since we found in our pilot study that this value was associated with the best discriminating ability for identifying patients developing MACE. In the third year, genetic background determining the PFA-100 closure time and levels of plasma markers of platelet activation will be explored by analyzing the relationships between various SNP/haplotype patterns and values of different platelet function assessments.

Clinical Significance-The present study will be the first to explore the clinical role of platelet function assessment both at baseline, after high-dose clopidogrel loading, and at study end. It may give us great insights regarding how to treat high-risk patients adequately with antiplatelet agents.

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 150 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: Validation of the Clinical Applicability of Various Platelet Function Assessments in High-Risk Atherothrombotic Patients Undergoing Percutaneous Coronary Angioplasty: Phase 4 Study
Study Start Date : July 2006
Estimated Primary Completion Date : June 2011
Estimated Study Completion Date : July 2011

Resource links provided by the National Library of Medicine

Arm Intervention/treatment
Active Comparator: c6
Clopidogrel 600 mg loading
Drug: Clopidogrel
Clopidogrel 600 mg loading

Primary Outcome Measures :
  1. the occurrence of major cardiovascular events (MACE)(death, myocardial infarction, stroke, and clinically driven target lesion revascularization) [ Time Frame: 1 year ]

Secondary Outcome Measures :
  1. the correlations between various platelet parameters and coronary angiographic findings [ Time Frame: 1 year ]
  2. the correlations among different platelet function measurements [ Time Frame: 1 year ]
  3. the responsiveness of CADP-CT on high-dose clopidogrel loading [ Time Frame: 1 year ]

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 80 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Coronary artery disease

Exclusion Criteria:

  • History of bleeding diathesis
  • History of drug or alcohol abuse or liver disease
  • Abnormal prothrombin time
  • Abnormal platelet count
  • Serum creatinine >1.5 mg/dl.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00513149

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Contact: Tzung-Dau Wang, M.D.,Ph.D. 886-2-23123456 ext 5632

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Division of Cardiology, Department of Internal Medicine and Department of Medical Imaging, National Taiwan University Hospital Recruiting
Taipei, Taiwan, 100
Contact: Tzung-Dau Wang, MD, PhD    886-2-2312-3456 ext 5632   
Principal Investigator: Tzung-Dau Wang, MD, PhD         
Sponsors and Collaborators
National Taiwan University Hospital
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Study Chair: Tzung-Dau Wang, M.D.,Ph.D. National Taiwan University Hospital
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Responsible Party: Tzung-Dau Wang, M.D., Ph.D., NTUH Identifier: NCT00513149    
Other Study ID Numbers: 200612040R
First Posted: August 8, 2007    Key Record Dates
Last Update Posted: January 24, 2011
Last Verified: January 2011
Keywords provided by National Taiwan University Hospital:
coronary artery disease
Additional relevant MeSH terms:
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Coronary Artery Disease
Myocardial Ischemia
Coronary Disease
Heart Diseases
Cardiovascular Diseases
Arterial Occlusive Diseases
Vascular Diseases
Platelet Aggregation Inhibitors
Purinergic P2Y Receptor Antagonists
Purinergic P2 Receptor Antagonists
Purinergic Antagonists
Purinergic Agents
Neurotransmitter Agents
Molecular Mechanisms of Pharmacological Action
Physiological Effects of Drugs