New Frontiers in AFib: Heart Device Noninferior to Blood Thinners in Stroke Prevention, Wins on Safety

In a landmark presentation today at the American College of Cardiology’s 2026 Annual Scientific Session (ACC.26), researchers unveiled data that could fundamentally shift how millions of patients manage stroke risk associated with atrial fibrillation (AFib). The CHAMPION-AF trial demonstrated that a specialized medical device used to seal off a small pouch in the heart is just as effective as modern blood-thinning medications for preventing strokes—and significantly safer when it comes to long-term bleeding risks.^1,2

The trial focused on left atrial appendage closure, a procedure that uses a device—specifically the WATCHMAN FLX in this study—to close a small pouch where over 90% of stroke-causing blood clots originate in patients with non-valvular AFib. While blood thinners, or non-vitamin K antagonist oral anticoagulants (NOACs), have long been the gold standard, the new data suggest that a one-time procedure may be a “reasonable alternative” even for patients who can tolerate medication.^1,2

AFib is the most common abnormal heart rhythm, affecting approximately 1 in 22 Americans. The condition increases the risk of stroke fivefold, as blood can pool in the heart and form clots that eventually travel to the brain. Currently, the WATCHMAN device is largely reserved for patients who cannot tolerate long-term blood thinners due to a high risk of bleeding. However, CHAMPION-AF sought to determine if the device could serve as a first-line therapy for a broader group of patients who have no contraindications to medication.¹

The study was massive in scope, enrolling 3000 patients across 141 sites in countries including the United States, Germany, Japan, and the United Kingdom. The participants, with an average age of 72, were randomized to either receive the WATCHMAN FLX device or continue with standard NOAC therapy.²

After 3 years of follow-up, the results were definitive. The primary efficacy end point—a composite of ischemic stroke, hemorrhagic stroke, cardiovascular death, and systemic embolism—occurred in 5.7% of the device group compared to 4.8% in the medication group. This result met the statistical threshold for noninferiority, meaning the device performed just as well as the drugs in preventing these life-threatening events.^1,2

However, the trial's most striking finding involved patient safety. Researchers found that patients relying on blood thinners had nearly twice the rate of bleeding events compared to those who received the heart device. Specifically, major and non-major bleeding occurred in 19% of the medical therapy group, compared to just 10.9% in the device group. This is particularly notable because the study participants were considered "low risk" for bleeding at the start of the trial.^1,2

“These numbers are very consistent with the current commercial data of this device at the present time, as reported in the [American College of Cardiology National Cardiovascular Data Registry],” said presenter and co-principal investigator Saibal Kar, MD, in the late-breaking clinical trial session at ACC.26.³

Kar noted that while NOACs are effective, their utility is often limited by medication non-adherence and the persistent risk of internal bleeding over time. By closing the left atrial appendage, the source of potential clots is physically eliminated, potentially removing the need for a lifetime of daily pills.¹

There were, however, some nuances in the data. While deaths and systemic embolisms were similar between both groups, researchers did observe a slightly higher rate of ischemic strokes in the device group (3.2%) versus the medication group (2.0%). Kar characterized these event rates as "low in both groups" and stated that the team would be scrutinizing these numbers again at the 5-year mark.^1-3

The implications of CHAMPION-AF are expected to be far-reaching, potentially leading to a shared decision-making process between physicians and patients regarding whether to choose a lifetime of medication or a one-time catheter-based procedure. The study was funded by Boston Scientific, the manufacturer of the WATCHMAN device, and the results were simultaneously published in the New England Journal of Medicine.¹

As the medical community awaits the 5-year follow-up data, the 3-year results presented in New Orleans mark a significant milestone. For the millions of people living with AFib, the choice of how to protect their brain and heart may have just become a lot more personal.

REFERENCES

1. Left atrial appendage closure noninferior to blood thinners for lowering stroke risk, death in some patients with AFib. News release. American College of Cardiology. March 28, 2026. Accessed March 28, 2026.

2. Kar S, Doshi SK, Nair DG, et al. Outcomes in patients with atrial fibrillation randomized to receive left atrial appendage closure or oral anticoagulation: primary results of the CHAMPION-AF clinical trial. Presented at: American College of Cardiology 2026 Scientific Sessions. March 28, 2026; New Orleans, LA.

3. Kar S. Outcomes in patients with atrial fibrillation randomized to receive left atrial appendage closure or oral anticoagulation: primary results of the CHAMPION-AF clinical trial. Presented at: American College of Cardiology 2026 Scientific Sessions. March 28, 2026; New Orleans, LA.