for people ages 18 years and up (full criteria)
at Irvine, California and other locations
study started
estimated completion



Researchers are looking for a better way to treat people with atrial fibrillation and prevent stroke or systemic embolism (blood clots travelling through the blood stream to plug another vessel).

Atrial fibrillation is a condition of having irregular and often rapid heartbeat. It can lead to the formation of blood clots in the heart which can travel through the blood stream to plug another vessel, and like this lead to serious and life-threatening conditions, such as a stroke. A stroke occurs because the brain tissue beyond the blockage no longer receives nutrients and oxygen so that brain cells die. As strokes arising from atrial fibrillation can involve extensive areas of the brain, it is important to prevent them.

Blood clots are formed in a process known as coagulation. Medications are already available to prevent the formation of blood clots. When taken by mouth (orally), they are known as oral anticoagulants (OACs) including apixaban. OACs decrease the risk of the above-mentioned serious and life-threatening conditions. The main side effect of OACs is an increase of the risk of bleeding.

The study treatment asundexian is a new type of anticoagulant currently under development to provide further treatment options. The way it works, it aims to further improve the standard of care with regard to the risk of bleeding.

The main purpose of this study is to collect more data about how well asundexian works to prevent stroke and systemic embolism and how safe it is compared to apixaban in people with atrial fibrillation and at high risk for stroke.

To see how well the study treatment asundexian works researchers compare:

  • how long asundexian works well and
  • how long apixaban works well after the start of the treatment. Working well means that the treatments can prevent the following from happening:
  • stroke and/or
  • systemic embolism. The study will keep collecting data until a certain number of strokes or embolisms happen in the study.

To see how safe asundexian is, the researchers will compare how often major bleedings occur after taking the study treatments asundexian and apixaban, respectively. Major bleedings are bleedings that have a serious or even life-threatening impact on a person's health.

The study participants will be randomly (by chance) assigned to 1 of 2 treatment groups, A and B. Dependent on the treatment group, the participants will either take the study treatment asundexian by mouth once a day or apixaban by mouth twice a day for approximately 9 - 33 months.

Each participant will be in the study for approximately 9 - 34 months. There will be visits to the study site every 3 to 6 months and up to 7 phone calls. Those participants who do not want or are unable to have visits to the study site may join the study remotely in selected countries. All visits for these participants will be done using electronic devices.

During the study, the study team will:

  • take blood samples
  • do physical examinations
  • examine heart health using an electrocardiogram (ECG)
  • check vital signs such as blood pressure and heart rate
  • do pregnancy tests
  • ask the participants questions about their quality of life
  • ask the participants questions about how they are feeling and what adverse events they are having.

An adverse event is any medical problem that a participant has during a study. Doctors keep track of all adverse events that happen in studies, even if they do not think the adverse events might be related to the study treatments.

Official Title

A Multicenter, International, Randomized, Active Comparator-controlled, Double-blind, Double-dummy, Parallel-group, 2-arm, Phase 3 Study to Compare the Efficacy and Safety of the Oral FXIa Inhibitor Asundexian (BAY 2433334) With Apixaban for the Prevention of Stroke or Systemic Embolism in Male and Female Participants Aged 18 Years and Older With Atrial Fibrillation at Risk for Stroke


Prevention of Stroke or Systemic Embolism, Atrial Fibrillation, Stroke, Embolism, Apixaban, Asundexian (BAY2433334), Asundexian


You can join if…

Open to people ages 18 years and up

  • 18 years of age or older (at legal age of consent according to local legislation) at the time of signing the informed consent
  • Atrial fibrillation documented by ECG evidence with an indication for indefinite treatment with an oral anticoagulant
  • CHA2DS2-VASc score ≥ 3 if male or ≥ 4 if female, OR CHA2DS2-VASc score of 2 if male or 3 if female and enrichment criteria.

You CAN'T join if...

  • Mechanical heart valve prosthesis
  • Moderate-to-severe mitral stenosis at the time of inclusion into the study
  • Atrial fibrillation only due to reversible cause
  • Requirement for chronic anticoagulation for a different indication than AF


  • University of California, Irvine not yet accepting patients
    Irvine California 92697 United States
  • Radin Cardiovascular Medical Group, Inc. not yet accepting patients
    Newport Beach California 92685 United States
  • VA Long Beach Healthcare System not yet accepting patients
    Long Beach California 90822 United States
  • VA Greater Los Angeles Healthcare System accepting new patients
    Los Angeles California 90073 United States
  • Harbor - UCLA Medical Center not yet accepting patients
    Torrance California 90502-2004 United States
  • Lundquist Institute Harbor-UCLA | Cardiac CT | Div of Cardio not yet accepting patients
    Torrance California 90502-2004 United States
  • Valley Clinical Trials, Inc. - Covina accepting new patients
    Covina California 91723 United States


accepting new patients at some sites,
but this study is not currently recruiting here
Start Date
Completion Date
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Phase 3 research study
Study Type
Expecting 18000 study participants
Last Updated