Clot Chronicles: The AZALEA Trial from AHA 2023

Welcome to Clot Chronicles, a series highlighting contributions from our Executive and Medical Advisory Boards to keep you up to date on the latest thrombosis research. Along with concise, clinically focused summaries, you’ll also have access to videos featuring our board members and their work.

In this breaking news video, NATF Advisory Board Member, Behnood Bikdeli, MD, MS, and NATF President, Christian Ruff, MD, MPH, discuss the AZALEA trial, which was presented as late-breaking science at the American Heart Association Scientific Sessions this past weekend.


Although anticoagulants such as vitamin K antagonists, low-molecular-weight heparin, and DOACs are effective in many scenarios, bleeding risk has been prohibitive. It has been hypothesized that inhibiting factor XI may “uncouple” thrombosis from hemostasis.

Top 3 Takeaways

  1. In a phase IIb randomized clinical trial of patients with atrial fibrillation (AZALEA TIMI-71), both tested doses of abelacimab were associated with substantial (~70%) reduction in major or clinically relevant nonmajor bleeding.
  2. Results were consistent for major bleeding. GI bleeding was almost completely eliminated!
  3. Although not powered for ischemic outcomes, no major differences were observed in such events between groups.

Implications for Clinical Practice

Abelacimab is not yet approved by the FDA or EMA for clinical use. Additional trials are ongoing with abelacimab and other inhibitors of factor XI/ XIa. However, this trial sets up a very exciting landscape for the future care of patients in need of antithrombotic therapy, such as those with atrial fibrillation.


We encourage you to watch this short video to gain a deeper understanding of the study’s significance and potential implications for patient care.

See what Dr. Ruff, the study author, has to say about the AZALEA trial below!

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