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Study on Lowering INR to Reduce Bleeding in Patients with Mechanical Aortic Valves Using Warfarin, Acenocoumarol, and Phenprocoumon

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on patients who have undergone a mechanical bileaflet aortic valve replacement and are being treated with a Vitamin K Antagonist. The study aims to evaluate the safety and effectiveness of maintaining a lower INR (International Normalized Ratio) range in these patients. The INR is a measure used to determine the clotting tendency of blood, which is important for patients with mechanical heart valves to prevent complications such as blood clots or bleeding.

The trial involves the use of medications such as Warfarin, Acenocoumarol, and Phenprocoumon, which are all types of Vitamin K Antagonists. These medications help to thin the blood and prevent clot formation. Participants in the study will be randomly assigned to receive one of these medications or a placebo. The study will monitor the participants over a period of up to 36 months to observe any occurrences of blood clots, strokes, or bleeding events.

The purpose of the study is to determine if a lower INR range can safely reduce the risk of bleeding while still effectively preventing blood clots in patients with mechanical heart valves. Throughout the study, participants will have regular check-ups to monitor their health and the effects of the medication. The study will also track other health outcomes such as overall survival, any type of stroke, heart attacks, and other related conditions. This research is important to improve the management of patients with mechanical heart valves and to enhance their quality of life.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Enrollment

    Participation begins after providing written informed consent. This consent can be given by the patient or a substitute decision-maker.

    Eligibility requires having a bileaflet mechanical heart valve implant in the aortic position for at least 3 months and being at least 18 years old.

  2. Step 2

    Medication administration

    The trial involves the use of Vitamin K Antagonists such as acenocoumarol, warfarin, and phenprocoumon. These medications are taken orally.

    The specific dosage and frequency will be determined by the study protocol and monitored by the research team.

  3. Step 3

    Monitoring and assessments

    Regular monitoring of INR (International Normalized Ratio) levels is conducted to ensure they remain within a common, lower range. This is to evaluate the safety and efficacy of this range in patients with bileaflet aortic mechanical valves.

    Assessments will include checking for any signs of thrombosis, thromboembolism, and bleeding, which are primary endpoints of the study.

  4. Step 4

    Follow-up and evaluation

    Secondary endpoints such as all-cause mortality, all clinically important bleeding, and various types of strokes and thromboembolic events will be evaluated.

    The study will also track the time patients spend in the therapeutic range and the proportion of patients with extreme INR values.

  5. Step 5

    Completion

    The trial is estimated to conclude by December 31, 2026.

    Upon completion, data will be analyzed to determine the overall safety and effectiveness of maintaining a lower INR range in the specified patient group.

Who can join the trial?

3 criteria

  • Have had a bileaflet mechanical heart valve implant in the aortic position at least 3 months ago. This means you had a specific type of artificial heart valve placed in your heart's main artery at least 3 months ago.
  • Be at least 18 years of age at the time of enrollment. You must be 18 years old or older to join the study.
  • Provide written informed consent. This means you or someone who can make decisions for you must sign a document agreeing to participate in the study after understanding what it involves.

Who cannot join the trial?

4 criteria

  • Patients who are not being treated with a Vitamin K Antagonist. This is a type of medication that helps prevent blood clots.
  • Patients who do not have a mechanical bileaflet aortic valve replacement. This is a type of artificial heart valve used to replace a damaged one.
  • Patients who are not within the specified age range for the study.
  • Patients who belong to a vulnerable population, which means they might need special protection or care.
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Investigated drugs

Warfarin is a medication used to prevent blood clots. In this trial, it is being studied to see if using a lower range of its effect, measured by a blood test called INR, can safely reduce bleeding risks in patients with mechanical heart valves.

What is already known about the treatment

Vitamin K Antagonist – This medication is typically administered orally and is used to manage blood clotting in patients with mechanical bileaflet aortic valve replacements. It is well-established in medical practice and literature as a standard treatment for preventing blood clots in such patients. The main therapeutic indication is to maintain a specific range of blood clotting time, known as INR, to minimize the risk of bleeding while preventing clot formation. At the molecular level, it works by inhibiting the action of vitamin K, which is essential for the synthesis of certain clotting factors in the liver. It is classified pharmacologically as an anticoagulant.

Investigated diseases

  • Thrombosis

    Thrombosis is a condition where blood clots form in blood vessels, potentially obstructing blood flow. It can occur in veins or arteries and may lead to complications such as stroke or heart attack. The clot can remain in place or travel to other parts of the body, causing further blockages. Symptoms depend on the location of the clot and may include pain, swelling, or redness. If untreated, it can lead to tissue damage due to restricted blood flow.

  • Thromboembolism

    Thromboembolism occurs when a blood clot breaks loose and travels through the bloodstream, potentially causing blockages in other vessels. This can lead to serious conditions like pulmonary embolism or stroke. The condition often arises from deep vein thrombosis, where clots form in the deep veins of the legs. Symptoms vary based on the location of the blockage and may include sudden shortness of breath, chest pain, or leg swelling. It is a significant risk in patients with certain heart conditions or after surgery.

  • Ischemic Stroke

    An ischemic stroke happens when a blood clot blocks or narrows an artery leading to the brain, reducing blood flow and oxygen. This can cause brain cells to die, leading to loss of function in the affected area. Symptoms may include sudden numbness, confusion, trouble speaking, or loss of balance. It is the most common type of stroke and requires immediate medical attention to minimize brain damage.

  • Systemic Thromboembolism

    Systemic thromboembolism refers to a condition where a blood clot travels through the bloodstream and lodges in a distant blood vessel, affecting organs such as the brain, kidneys, or limbs. This can lead to organ damage or failure due to restricted blood flow. Symptoms depend on the affected organ and may include pain, dysfunction, or sudden changes in health status. It is often associated with heart conditions that increase clot formation risk.

  • Valve Thrombosis

    Valve thrombosis is the formation of a blood clot on a heart valve, which can impair its function. This condition is more common in patients with mechanical heart valves. Symptoms may include shortness of breath, fatigue, or heart palpitations. It can lead to serious complications if the clot obstructs blood flow or causes valve malfunction. Regular monitoring is essential for individuals with mechanical valves to prevent this condition.

  • Major Bleeding

    Major bleeding is a severe loss of blood that can occur internally or externally, often as a complication of anticoagulant therapy. It can lead to significant health issues, including shock or organ failure, if not managed promptly. Symptoms may include visible bleeding, dizziness, or a drop in blood pressure. It requires immediate medical attention to control the bleeding and stabilize the patient.

Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-508532-56-00Protocol code2019.06.26Estimated enrolment2 625 patientsSponsorHamilton Health Sciences Corporation

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