Three-year results suggest procedure may be a reasonable alternative to NOACs

NEW ORLEANS (March 28, 2026) — For patients with non-valvular atrial fibrillation (AFib) who had no contraindications to taking oral anticoagulants, the use of a device to close off the left atrial appendage in the heart—a small pouch where blood can pool and form dangerous clots—was comparable to standard medication therapy in reducing the combined rate of all-cause stroke, cardiovascular death and systemic embolism at three years. Moreover, closure of this appendage was found superior to long-term oral anticoagulation for pre-specified major and non-major non-procedural bleeding in these patients, according to research presented at the American College of Cardiology’s Annual Scientific Session (ACC.26).

AFib is the most common abnormal heart rhythm, affecting about 1 in 22 Americans. AFib also increases a person’s risk of stroke or systemic embolism, both life-threatening conditions caused by blood clots that can travel from the heart and block an artery. People with AFib are nearly five times more likely to suffer a severe, disabling stroke than those without the condition. In people with non-valvular AFib, over 90% of these stroke-causing blood clots originate in the left atrial appendage. The left atrial appendage closure device used in this trial is currently indicated and FDA approved for use in patients with atrial fibrillation who cannot tolerate or take long-term anticoagulants due to previous bleeding episodes or a high risk of bleeding, especially if they are prone to falls.

Unknown until this trial, according to researchers, is whether left atrial appendage closure is at least as effective and safe as blood thinners in this group of patients.

“Although non-vitamin K antagonist oral anticoagulants, also called NOACs, are currently the preferred treatment approach for reducing stroke risk in these patients, their effectiveness may be limited by risks associated with bleeding and medication non-adherence,” said Saibal Kar, MD, program director, cardiovascular disease fellowship at Los Robles Regional Medical Center in California, National Physician Director, Interventional Cardiology at HCA Healthcare USA and co-principal investigator of the study. “Our data suggest that the left atrial appendage closure device used in this trial is a potential and reasonable alternative to medication—even among patients who are suitable for long-term blood thinners—and may be discussed as part of a shared decision-making process.”

CHAMPION-AF is the first prospective, multinational, randomized trial to test whether left atrial appendage closure is noninferior to NOACs in patients who are able to take long-term blood thinners irrespective of whether they have undergone prior AFib ablation. The study included 3,000 patients (average age 72 years, 32% women, 85% White) with non-valvular AFib who had a moderately elevated risk of stroke (average CHA2DS2-VASc score of 3.5) and low bleeding risk (mean HAS-BLED score of 1.3) at 141 sites across Australia, Belgium, Canada, Denmark, France, Germany, Israel, Italy, Japan, Netherlands, Poland, Saudi Arabia, Spain, Switzerland, United Kingdom and the United States. A total of 1,501 patients were randomized to receive a NOAC at the discretion of the treating physician and 1,499 were randomized to undergo left atrial appendage closure with the WATCHMAN FLX device, which was inserted via a thin tube (catheter) through a blood vessel in the groin.

After three years of follow-up, 5.7% of patients in the left atrial appendage closure group and 4.8% of those in the medical therapy group experienced the trial’s primary efficacy endpoint—a composite rate of ischemic stroke, hemorrhagic stroke, cardiovascular death and systemic embolism—which met noninferiority, Kar said. When researchers looked at each of the components of this co-primary endpoint individually, they found no difference in deaths, systemic embolism or hemorrhagic strokes, but saw slightly more ischemic strokes among those undergoing the procedure.

“There was a slightly higher number of ischemic strokes among people in the left atrial appendage closure group—3.2% versus 2% among those in the medical therapy group, but event rates were low in both groups—and this is something we will look at again at five years,” Kar said.

Results for the primary safety endpoint—the combined occurrence of major and non-major, but clinically relevant, non-procedural bleeding at three years—showed that those in the medical therapy group had almost twice the rate of bleeding events. Bleeding occurred in 10.9% of those in the left atrial appendage closure group and 19% of those in the medical therapy group.

“This is an important finding because we studied people who we thought were good candidates for blood thinners—they are not contraindicated for long-term anticoagulation and they have low bleeding risk—and in spite of that, they had increased bleeding over time,” Kar said.

The study also had two prespecified secondary endpoints, and met both, according to Kar. The first secondary endpoint—the combined rate of major bleeding (procedural and non-procedural) at three years —met noninferiority for left atrial appendage closure (5.9% in the left atrial appendage closure group and 6.4% in the medical therapy group).

The secondary net clinical benefit endpoint was a composite of cardiovascular death, stroke, systemic embolism and non-procedural bleeding. Data demonstrated the left atrial appendage closure device was superior to medical therapy (15.1% vs. 21.8%, respectively).

The team also conducted a secondary analysis that looked at major and clinically relevant non-major procedural and non-procedural bleeding and found that at three years, the left atrial appendage closure group had fewer events compared to the medical therapy group (12.8% vs. 19%, respectively).

Because the trial only used a single device, the WATCHMAN FLX, and a specific post-implant treatment regimen, the results may not be generalizable to all left atrial appendage closure devices. The results may also not apply to patients with advanced heart failure with very low ejection fractions as those patients were excluded from the study.

Kar and team will follow patients for five years to determine whether left atrial appendage closure is non-inferior to blood thinners for ischemic stroke and systemic embolism over the longer term.

The study was funded by Boston Scientific, manufacturer of the WATCHMAN device.

This study was simultaneously published online in the New England Journal of Medicine at the time of presentation.

Kar will present the study, “Outcomes In Patients With Atrial Fibrillation Randomized To Receive Left Atrial Appendage Closure Or Oral Anticoagulation: Primary Results Of The CHAMPION-AF Clinical Trial,” on Saturday, March 28, at 9:30 a.m. CT / 14:30 UTC in the Main Tent, Great Hall.

ACC.26 will take place March 28-30, 2026, in New Orleans, bringing together cardiologists and cardiovascular specialists from around the world to share the newest discoveries in treatment and prevention. Follow @ACCinTouch, @ACCMediaCenter and #ACC26 for the latest news from the meeting.

The American College of Cardiology (ACC) is the global leader in transforming cardiovascular care and improving heart health for all. As the preeminent source of professional medical education for the entire cardiovascular care team since 1949, ACC credentials cardiovascular professionals in over 140 countries who meet stringent qualifications and leads in the formation of health policy, standards and guidelines. Through its world-renowned family of JACC Journals, NCDR registries, ACC Accreditation Services, global network of Member Sections, CardioSmart.org patient resources and more, the College is committed to ensuring a world where science, knowledge and innovation optimize patient care and outcomes. Learn more at ACC.org.

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