Platelet Reactivity After CABG

This study has been completed.
Information provided by (Responsible Party):
David J. Schneider, MD, University of Vermont Identifier:
First received: February 13, 2013
Last updated: September 20, 2015
Last verified: September 2015

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.

Acute Coronary Syndrome

Study Type: Observational
Study Design: Observational Model: Cohort
Time Perspective: Prospective
Official Title: Platelet Activation, Reactivity, and Inflammation After Coronary Bypass Surgery In Patients Treated With Ticagrelor or Clopidogrel

Resource links provided by NLM:

Further study details as provided by University of Vermont:

Primary Outcome Measures:
  • reactivity of juvenile platelets [ Time Frame: 16-24 hours after CABG ] [ Designated as safety issue: No ]
    We will use flow cytometry to identify juvenile platelets and assess their likelihood to activate in response to a submaximal concentration of agonist.

Secondary Outcome Measures:
  • platelet-leukocyte aggregates [ Time Frame: 16-24 hours after CABG ] [ Designated as safety issue: No ]
    We will identify the prevalence of platelet-leukocyte aggregates - a marker of platelet activation in vivo

  • platelet microparticles [ Time Frame: 16-24 hours after CABG ] [ Designated as safety issue: No ]
    We will quantify the prevalence of platelet microparticles, reflecting platelet activation in vivo

  • cytokine/chemokine array [ Time Frame: 16-24 hours after CABG ] [ Designated as safety issue: No ]
    We will quantify the concentration of common cytokines and chemokines.

Biospecimen Retention:   Samples Without DNA

Platelets and leukocytes will be evaluated acutely. Plasma will be stored for cytokine and chemokine analysis.

Enrollment: 18
Study Start Date: May 2013
Study Completion Date: September 2015
Primary Completion Date: September 2015 (Final data collection date for primary outcome measure)
previous treatment with clopidogrel
previous treatment with ticagrelor


Ages Eligible for Study:   18 Years and older
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No
Sampling Method:   Non-Probability Sample
Study Population

Patients with acute coronary syndrome who based on clinical indications require urgent CABG. CABG is scheduled for clinical indications within 48 hours. Previous treatment with clopidogrel or ticagrelor.


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
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Please refer to this study by its identifier: NCT01793597

United States, Vermont
University of Vermont Medical Center
Burlington, Vermont, United States, 05401
Sponsors and Collaborators
University of Vermont
  More Information

No publications provided

Responsible Party: David J. Schneider, MD, Professor Of Medicine, Director of Cardiology, University of Vermont Identifier: NCT01793597     History of Changes
Other Study ID Numbers: ISSBRIL0095
Study First Received: February 13, 2013
Last Updated: September 20, 2015
Health Authority: United States: Institutional Review Board

Keywords provided by University of Vermont:
Coronary artery bypass surgery
platelet function
receptor binding
platelet reactivity
reversible binding

Additional relevant MeSH terms:
Myocardial Ischemia
Acute Coronary Syndrome
Angina Pectoris
Cardiovascular Diseases
Chest Pain
Heart Diseases
Signs and Symptoms
Vascular Diseases
Hematologic Agents
Molecular Mechanisms of Pharmacological Action
Neurotransmitter Agents
Pharmacologic Actions
Physiological Effects of Drugs
Platelet Aggregation Inhibitors
Purinergic Agents
Purinergic Antagonists
Purinergic P2 Receptor Antagonists
Purinergic P2Y Receptor Antagonists
Therapeutic Uses processed this record on October 02, 2015