Atrial fibrillation (AF) is a common heart condition that affects about one in three people at some point in their lives.
It increases the risk of stroke because blood clots can form in the heart and travel to the brain, causing severe damage.
To lower this risk, patients with AF are often prescribed anticoagulants, or blood thinners.
However, many patients avoid these medications or stop taking them due to concerns about bleeding complications, which remain a major challenge in treating AF.
Researchers from Mass General Brigham recently studied a new class of anticoagulants called Factor XI inhibitors. Their trial, known as AZALEA-TIMI 71, focused on a drug called abelacimab.
The findings, published in the New England Journal of Medicine, revealed that abelacimab significantly reduces bleeding compared to rivaroxaban, a commonly prescribed anticoagulant. These results could offer a safer alternative for AF patients who need stroke prevention but are worried about the risks of bleeding.
The AZALEA-TIMI 71 study is the largest and longest trial to date comparing a Factor XI inhibitor with standard anticoagulants. It involved 1,287 participants from 95 locations worldwide.
The participants were randomly assigned to receive either monthly injections of abelacimab (at doses of 150 mg or 90 mg) or daily doses of rivaroxaban (20 mg or 15 mg, depending on patient needs).
The results were impressive. The 150 mg dose of abelacimab reduced bleeding that required hospitalization or medical care by 62%, while the 90 mg dose reduced it by 69%, compared to rivaroxaban. Gastrointestinal bleeding, the most common type of bleeding with current anticoagulants, was nearly eliminated in patients taking abelacimab.
Importantly, stroke rates were low across all groups, with no significant differences between abelacimab and rivaroxaban. This suggests that abelacimab offers similar stroke protection but with far fewer bleeding risks.
The trial was stopped early after a recommendation from the Data Monitoring Committee, which found overwhelming evidence of reduced bleeding with abelacimab.
Dr. Christian Ruff, the principal investigator of the study, emphasized the importance of these findings, stating, “Factor XI inhibitors live up to their promise of superior safety. Bleeding is one of the greatest challenges in managing cardiovascular disease, and this represents a tremendous step forward.”
While AZALEA-TIMI 71 was not designed to assess how well abelacimab prevents strokes, its safety profile opens the door for further studies. A Phase III trial, called LILAC-TIMI 76, is already underway.
This trial will compare the 150 mg dose of abelacimab to a placebo in patients with AF who are considered too high-risk for current anticoagulants. The goal is to determine if abelacimab can effectively prevent strokes and other complications in these patients.
The results of the AZALEA-TIMI 71 study highlight the potential of Factor XI inhibitors like abelacimab to revolutionize stroke prevention in AF patients.
By significantly reducing bleeding risks, these drugs could make anticoagulant therapy safer and more acceptable for a wider range of patients. This is particularly important for those who avoid or discontinue treatment due to fear of complications.
In conclusion, abelacimab represents a promising advance in the treatment of atrial fibrillation. While more research is needed to confirm its effectiveness in preventing strokes, its safety profile is a major breakthrough.
As we await the results of ongoing Phase III trials, the cardiovascular field is optimistic about the potential of Factor XI inhibitors to improve care for millions of patients worldwide.
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The research findings can be found in New England Journal of Medicine.
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