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Study Comparing Apixaban and Warfarin for Patients with Heart Clots After a Heart Attack

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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 studying the treatment of patients who have a condition called left ventricular thrombosis, which can occur after a heart attack, also known as an acute myocardial infarction (AMI). The study is comparing two medications: apixaban and warfarin. Both of these medications are used to prevent blood clots, but they work in different ways. The purpose of the study is to see which medication is more effective in helping to dissolve blood clots in the heart after a heart attack.

Participants in the study will be randomly assigned to receive either apixaban or warfarin. The study will last for about three months, during which time the participants will take their assigned medication. The progress of the blood clot resolution will be monitored using a test called a transthoracic echocardiogram (TTE), which is a type of ultrasound that looks at the heart. If the TTE does not provide clear results, other imaging tests like magnetic resonance imaging (MRI) or computed tomography (CT) may be used.

Throughout the study, researchers will also keep track of any bleeding events, as both medications can increase the risk of bleeding. They will look at different types of bleeding, such as bleeding in the brain or gastrointestinal bleeding, and will also monitor for any major heart-related events. The study aims to provide valuable information on the best treatment option for patients with blood clots in the heart following a heart attack.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Upon joining the study, participants must be at least 18 years old and have a confirmed left ventricular thrombus, which is a blood clot in the heart, after a heart attack. This confirmation is done using heart imaging tests like an echocardiogram, MRI, or CT scan.

    Participants must provide written consent to participate, agreeing to follow the study's requirements and restrictions.

  2. Step 2

    Medication administration

    Participants will be randomly assigned to receive either apixaban or warfarin. Apixaban is given as a 2.5 mg or 5 mg film-coated tablet taken orally. Warfarin is given as a 2.5 mg tablet taken orally.

    The purpose of these medications is to help resolve the blood clot in the heart.

  3. Step 3

    Treatment duration

    The treatment with the assigned medication will continue for a period of 3 months.

    During this time, participants will be monitored for any side effects or complications.

  4. Step 4

    Evaluation of thrombus resolution

    After 3 months, the resolution of the blood clot will be evaluated using a transthoracic echocardiogram, which is a type of heart ultrasound. If the results are unclear, further imaging with MRI or CT may be used.

  5. Step 5

    Monitoring for secondary outcomes

    Throughout the study, participants will be monitored for any bleeding events, which are classified by severity, and for any major cardiovascular events such as another heart attack or stroke.

    The study will also assess the overall clinical benefit, which includes both the resolution of the blood clot and any bleeding events.

  6. Step 6

    Follow-up

    Participants will be followed up for a total of 12 months to check for any recurrence of the blood clot in the heart.

    The study is expected to conclude by the end of 2028.

Who can join the trial?

5 criteria

  • Participants must be **18 years or older** at the time of signing the informed consent.
  • Must have a **left ventricular thrombus**, which is a blood clot in the heart's left ventricle, confirmed by a **transthoracic echocardiogram (TTE)**, or if the results are unclear, confirmed by **cardiac magnetic resonance imaging (MRI)** or **computed tomography (CT)** within 1 to 28 days after an **acute myocardial infarction (AMI)**, which is a heart attack.
  • The participant must have given their **written consent** to join the trial, agreeing to follow the rules and restrictions in the informed consent form and study protocol.
  • For female participants:
    • Women who can have children must provide a **negative pregnancy test** at the start, not be breastfeeding, and agree to use **highly effective birth control** during the treatment and for up to 3 months after the last dose of the study drug.
    • Women who cannot have children must be **1 year post-menopausal**, meaning they have not had a menstrual period for one year.

Who cannot join the trial?

2 criteria

  • Patients with a history of **left ventricular thrombosis** cannot participate. This is a condition where a blood clot forms in the left lower chamber of the heart.
  • Patients who have had an **acute myocardial infarction (AMI)** are excluded. This is commonly known as a heart attack, which happens when blood flow to the heart is blocked.
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Investigated drugs

  • Apixaban

    is a medication used to prevent blood clots. In this clinical trial, it is being tested to see how well it helps dissolve blood clots in the heart after a heart attack. It works by blocking certain proteins in the blood that are involved in clotting.

  • Warfarin

    is another medication used to prevent blood clots. It is being compared to apixaban in this study to see which one is more effective at resolving blood clots in the heart after a heart attack. Warfarin works by reducing the formation of blood clots by interfering with the action of vitamin K, which is necessary for blood clotting.

What is already known about the treatment

  • Apixaban

    Apixaban is administered orally in tablet form. It is currently well-established in medical practice and literature as an anticoagulant. The main therapeutic indications for apixaban include the prevention and treatment of blood clots, particularly in conditions like left ventricular thrombosis and after acute myocardial infarction. At the molecular level, apixaban works by inhibiting Factor Xa, an enzyme crucial for blood clot formation. It is classified pharmacologically as a direct oral anticoagulant (DOAC).

  • Warfarin

    Warfarin is taken orally in tablet form. It has been a long-standing medication in medical literature and practice for its anticoagulant properties. Warfarin is primarily used to prevent and treat blood clots in conditions such as left ventricular thrombosis and following an acute myocardial infarction. Its mechanism of action involves inhibiting vitamin K epoxide reductase, which is essential for the synthesis of clotting factors. Warfarin is classified as a vitamin K antagonist.

Investigated diseases

  • Left Ventricular Thrombosis

    This condition involves the formation of a blood clot within the left ventricle of the heart. It often occurs after a heart attack, where the heart muscle is damaged, leading to changes in blood flow. The clot can restrict blood flow and may lead to further complications if it dislodges and travels to other parts of the body. Over time, the clot may either dissolve on its own or persist, potentially causing additional heart issues. Monitoring and management are crucial to prevent complications associated with this condition.

  • Acute Myocardial Infarction (AMI)

    Commonly known as a heart attack, this condition occurs when blood flow to a part of the heart is blocked for a long enough time that part of the heart muscle is damaged or dies. The blockage is usually caused by a buildup of fat, cholesterol, and other substances, which form a plaque in the coronary arteries. During an AMI, the affected heart muscle loses its ability to function properly, leading to symptoms such as chest pain, shortness of breath, and fatigue. The progression of AMI can lead to complications like heart failure or arrhythmias if not addressed promptly. Recovery involves the heart muscle healing, which can take weeks to months, depending on the severity of the attack.

Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-514416-28-00Estimated enrolment287 patientsSponsorKarolinska Institutet

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