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

June 20, 2012 updated by: Marc Ruel MD MPH FRCSC, Ottawa Heart Institute Research Corporation

"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"

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].

Study Overview

Status

Completed

Conditions

Intervention / Treatment

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

Study Type

Observational

Enrollment (Actual)

56

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Canada
    • Ontario
      • Ottawa, Ontario, Canada, K1Y 4W7
        • University of Ottawa Heart Institute

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

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).

Description

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.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
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

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Differences in the rate of doppler-detected cerebral micro emboli between the two prophylactic treatments of thrombosis
Time Frame: 1 month after surgery
1 month after surgery

Secondary Outcome Measures

Outcome Measure
Time Frame
Differences in the degree of inhibition of platelet aggregation between the two prophylactic treatments of thrombosis
Time Frame: 1 month after surgery
1 month after surgery

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Ottawa Heart Institute Research Corporation

Collaborators

Edwards Lifesciences

Investigators

  • Study Director: Thierry Mesana, MD, PhD, Ottawa Heart Institute Research Corporation

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

March 1, 2007

Primary Completion (Actual)

December 1, 2007

Study Completion (Actual)

March 1, 2011

Study Registration Dates

First Submitted

April 20, 2007

First Submitted That Met QC Criteria

April 20, 2007

First Posted (Estimate)

April 24, 2007

Study Record Updates

Last Update Posted (Estimate)

June 21, 2012

Last Update Submitted That Met QC Criteria

June 20, 2012

Last Verified

June 1, 2012

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2006785-01H

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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