Transcranial Doppler (TCD) Assessment During Early Anti-thrombotic Therapy After Bioprosthetic Aortic Valve Replacement (Tissue-Valve)

This study has been completed.
Sponsor:
Collaborator:
Edwards Lifesciences
Information provided by (Responsible Party):
Marc Ruel MD MPH FRCSC, University of Ottawa Heart Institute
ClinicalTrials.gov Identifier:
NCT00465218
First received: April 20, 2007
Last updated: June 20, 2012
Last verified: June 2012
  Purpose

The purpose of this study is to determine if there is any difference in the counts of cerebral emboli and platelet function between two prophylactic treatments of thrombosis currently used at University of Ottawa Heart Institute for the first three months after surgery in low-risk patients undergoing aortic valve replacement with a bioprosthetic valve: 1) daily use of high-dose aspirin [325 mgs], and 2) the combination of oral Warfarin [target INR 2.0 to 3.0] and low-dose aspirin [81 mg].


Condition Intervention Phase
Aortic Valve Disease
Procedure: Prophylaxis of Thrombosis after aortic valve replacement
Phase 1

Study Type: Observational
Study Design: Observational Model: Case Control
Time Perspective: Prospective
Official Title: "Transcranial Doppler Assessment of Cerebral Embolization During Early Anti-thrombotic Therapy After Bioprosthetic Aortic Valve Replacement: Comparison of High-dose Aspirin Versus Warfarin Plus Low-dose Aspirin"

Resource links provided by NLM:


Further study details as provided by University of Ottawa Heart Institute:

Primary Outcome Measures:
  • Differences in the rate of doppler-detected cerebral micro emboli between the two prophylactic treatments of thrombosis [ Time Frame: 1 month after surgery ] [ Designated as safety issue: No ]

Secondary Outcome Measures:
  • Differences in the degree of inhibition of platelet aggregation between the two prophylactic treatments of thrombosis [ Time Frame: 1 month after surgery ] [ Designated as safety issue: No ]

Enrollment: 56
Study Start Date: March 2007
Study Completion Date: March 2011
Primary Completion Date: December 2007 (Final data collection date for primary outcome measure)
Groups/Cohorts Assigned Interventions
1
High dose aspirin (325 mg)
Procedure: Prophylaxis of Thrombosis after aortic valve replacement
Two standard prophylactic treatments of thrombosis within the first 3 months postsurgery currently used in our institution: a) daily dose of aspirin (325 mgs; b) daily dose of aspirin (81 mg) plus Warfarin for target INR 2.0-2.5
2
Low dose aspirin (81 mgs) plus warfarin
Procedure: Prophylaxis of Thrombosis after aortic valve replacement
Two standard prophylactic treatments of thrombosis within the first 3 months postsurgery currently used in our institution: a) daily dose of aspirin (325 mgs; b) daily dose of aspirin (81 mg) plus Warfarin for target INR 2.0-2.5

Detailed Description:

Background:

There are several medications used to prevent blood clotting in patients undergoing surgical replacement of their aortic valves with tissue valves. One of these medications is called warfarin (Coumadin ®) which prevents blood clotting by making the blood "thinner." Another medication is aspirin which prevents the aggregation (clustering) of cells in the blood called platelets. Some clinicians consider that using only aspirin should be enough to protect the patients against the presence of clots in the blood, but others consider that aspirin should be combined with warfarin for better protection. Moreover, physicians express concern over the use of oral anticoagulation due to the possibility of an increased risk of bleeding. The effects of these medications for preventing blood clots traveling to the brain after the surgery are currently unknown. Transcranial doppler ultrasound will be used in these patients to evaluate non-invasively the quantity of fragments of clots circulating in the arteries of the brain. In addition, platelet function will be measured to determine how effective these treatments are for preventing the aggregation of the blood cells called platelets, which may be involved in clot formation.

Objective:

Our purpose is to determine if there is any difference in the counts of cerebral emboli and platelet function between two prophylactic treatments of thrombosis currently used in our institution for the first three months after surgery in these patients: 1) daily use of high-dose aspirin [325 mgs], and 2) the combination of oral Warfarin [target INR 2.0 to 3.0] and low-dose aspirin [81 mg].

Methods:

Patients with low risk profile undergoing primary aortic valve replacement with a bioprosthetic (tissue) valve will be eligible for the study. Patients will receive one of the two prophylactic treatments of thrombosis (1 or 2) depending on the surgeon's preference. Platelet function will be measured before surgery and transcranial doppler within the first 24 hours immediately after the surgery. At the end of one month following surgery, all patients will undergo transcranial doppler and platelet function assessment. The study will be powered on demonstrating the hypothesis of substantial equivalence between the two treatments as regarding the primary outcome (cerebral emboli).

Outcome measures:

  1. Primary outcome:

    Bilateral counts of cerebral emboli in the middle cerebral arteries with transcranial doppler ultrasound at one month after surgery

  2. Secondary outcomes:

Platelet function, incidence of major adverse neurologic and bleeding events at one month following surgery

  Eligibility

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 aortic valve stenosis and/or insuficiency undergoing aortic valve replacement with a bioprosthetic valve (tissue valve).

Criteria

Inclusion Criteria:

  • Patients undergoing primary aortic valve replacement with bioprosthetic (tissue) valve.

Exclusion Criteria:

  • Emergency surgery or redo operations.
  • Patients with history of transient ischemic attacks, stroke, or history of carotid stenosis greater than 50% as detected by carotid duplex doppler or angiography.
  • Patients with COPD who are CO2 retainers.
  • Patients with LV function less than 50%, or enlarged left ventricle greater than 50 mm as detected by echocardiography or previous history of thromboembolism.
  • Patients with history of atrial fibrillation or heart rhythm disturbances.
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00465218

Locations
Canada, Ontario
University of Ottawa Heart Institute
Ottawa, Ontario, Canada, K1Y 4W7
Sponsors and Collaborators
University of Ottawa Heart Institute
Edwards Lifesciences
Investigators
Principal Investigator: Marc Ruel, MD, MPH University of Ottawa Heart Institute
Study Director: Thierry Mesana, MD, PhD University of Ottawa Heart Institute
  More Information

Publications:

Responsible Party: Marc Ruel MD MPH FRCSC, Dr., University of Ottawa Heart Institute
ClinicalTrials.gov Identifier: NCT00465218     History of Changes
Other Study ID Numbers: 2006785-01H
Study First Received: April 20, 2007
Last Updated: June 20, 2012
Health Authority: Canada: Ethics Review Committee

Keywords provided by University of Ottawa Heart Institute:
Bioprosthesis
Thrombosis
Cerebral emboli
Transcranial Doppler
Platelet function tests

Additional relevant MeSH terms:
Heart Defects, Congenital
Heart Valve Diseases
Cardiovascular Abnormalities
Cardiovascular Diseases
Heart Diseases
Congenital Abnormalities
Aspirin
Anti-Inflammatory Agents, Non-Steroidal
Analgesics, Non-Narcotic
Analgesics
Sensory System Agents
Peripheral Nervous System Agents
Physiological Effects of Drugs
Pharmacologic Actions
Anti-Inflammatory Agents
Therapeutic Uses
Antirheumatic Agents
Fibrinolytic Agents
Fibrin Modulating Agents
Molecular Mechanisms of Pharmacological Action
Cardiovascular Agents
Hematologic Agents
Platelet Aggregation Inhibitors
Cyclooxygenase Inhibitors
Enzyme Inhibitors
Antipyretics
Central Nervous System Agents

ClinicalTrials.gov processed this record on September 18, 2014