CHAMPION-AF Data Presented for Boston Scientific’s Watchman FLX LAAC Device Versus NOACs

March 28, 2026—Boston Scientific Corporation announced that the CHAMPION-AF global clinical trial met all primary and secondary safety and efficacy endpoints.

According to Boston Scientific, CHAMPION-AF evaluated the company’s Watchman FLX left atrial appendage closure device compared to nonvitamin K antagonist oral anticoagulants (NOACs) as a first-line option for stroke risk reduction in a broad population of patients with nonvalvular atrial fibrillation.

Key results from the study were presented as a late-breaking clinical trial at ACC.26, the American College of Cardiology’s annual scientific session, and simultaneously published by Shephal K. Doshi, MD, et al in The New England Journal of Medicine.

As summarized in the company’s press release, the 36-month findings included the following:

• The study’s primary safety endpoint was met with the Watchman FLX device, demonstrating statistical superiority to NOACs (10.9% vs 19.0%; P < .001) for nonprocedural-related major and clinically relevant nonmajor bleeding with a 45% relative reduction in nonprocedural bleeding risk.
• When including procedural bleeding in a secondary analysis, the Watchman FLX device’s performance was consistent with the primary safety endpoint, demonstrating a significant reduction in bleeding compared to NOACs (12.8% vs 19.0%; P < .001) for major and clinically relevant nonmajor bleeding, representing a 34% relative reduction in procedural and nonprocedural bleeding risk.
• The primary efficacy endpoint—defined as occurrence of stroke, cardiovascular or unexplained death, or systemic embolism—was met, with the Watchman FLX device achieving statistical noninferiority compared to NOACs (5.7% vs 4.8%; P < .001).
• In the study’s secondary safety endpoint, the Watchman FLX device was statistically noninferior to NOACs for procedural and nonprocedural major bleeding (5.9% vs 6.4%; P < .001).
• A secondary combined safety and efficacy endpoint showed a net clinical benefit with the device, demonstrating statistical superiority to NOACs for the occurrence of cardiovascular death, stroke, systemic embolism, and nonprocedural major bleeding and clinically relevant nonmajor bleeding (15.1% vs 21.8%; P < .001).

“The success of the landmark CHAMPION-AF trial represents a meaningful milestone that will undoubtedly transform the treatment approach to stroke risk reduction in a broader population of patients who historically have needed to rely on medication,” commented study Cochair Martin Leon, MD, in Boston Scientific’s press release. “These results should give clinicians confidence in the potential of the Watchman FLX device to become a first-line treatment option for reducing the risk of stroke for a rapidly growing number of patients with AF.”