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Platelet Function Assessment for Atherothrombotic Patients

The recruitment status of this study is unknown. The completion date has passed and the status has not been verified in more than two years.
Verified January 2011 by National Taiwan University Hospital.
Recruitment status was:  Recruiting
Information provided by:
National Taiwan University Hospital Identifier:
First received: August 6, 2007
Last updated: January 20, 2011
Last verified: January 2011
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 Intervention Phase
Coronary Artery Disease Drug: Clopidogrel Phase 4

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: 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

Resource links provided by NLM:

Further study details as provided by National Taiwan University Hospital:

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

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

Estimated Enrollment: 150
Study Start Date: July 2006
Estimated Study Completion Date: July 2011
Estimated Primary Completion Date: June 2011 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: c6
Clopidogrel 600 mg loading
Drug: Clopidogrel
Clopidogrel 600 mg loading

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.


Ages Eligible for Study:   18 Years to 80 Years   (Adult, Senior)
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.
  Contacts and Locations
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Please refer to this study by its identifier: NCT00513149

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

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
Study Chair: Tzung-Dau Wang, M.D.,Ph.D. National Taiwan University Hospital
  More Information

Responsible Party: Tzung-Dau Wang, M.D., Ph.D., NTUH Identifier: NCT00513149     History of Changes
Other Study ID Numbers: 200612040R
Study First Received: August 6, 2007
Last Updated: January 20, 2011

Keywords provided by National Taiwan University Hospital:
coronary artery disease

Additional relevant MeSH terms:
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
Fibrinolytic Agents
Fibrin Modulating Agents
Cytochrome P-450 CYP2C19 Inhibitors
Cytochrome P-450 Enzyme Inhibitors
Enzyme Inhibitors processed this record on August 16, 2017