CHAMPION-AF Trial Shows Watchman FLX Device Non-Inferior to Blood Thinners for Stroke Prevention in Atrial Fibrillation
核心洞察
The CHAMPION-AF trial demonstrated that the Watchman FLX (搜索) left atrial appendage closure device was non-inferior to direct oral anticoagulants for preventing stroke, cardiovascular death, and systemic embolism in 3,000 atrial fibrillation patients over 36 months.
The device showed statistically superior protection from non-procedural bleeding compared to blood thinners, with a 45% relative reduction in bleeding risk (10.9% vs 19.0%).
Despite meeting primary endpoints, the trial faced criticism for higher stroke rates in the device arm and methodological limitations, with experts calling for careful patient selection and shared decision-making.
The landmark CHAMPION-AF trial has demonstrated that the Watchman FLX (搜索) left atrial appendage closure device is non-inferior to direct oral anticoagulants for stroke prevention in patients with atrial fibrillation, meeting all primary and secondary endpoints in the largest study of its kind to date.
The randomized, controlled trial enrolled 3,000 patients with non-valvular atrial fibrillation across 141 sites in 16 countries, comparing the Boston Scientific device to standard blood thinner therapy. Results were presented at the American College of Cardiology 2026 Scientific Session and simultaneously published in the New England Journal of Medicine.
Primary Endpoints Met with Mixed Reception
The study achieved its primary efficacy endpoint, with the composite of cardiovascular death, stroke, or systemic embolism occurring in 5.7% of patients receiving the Watchman FLX (搜索) device versus 4.8% in the anticoagulation group over 36 months. The between-group difference of 0.9% fell within the prespecified noninferiority margin of 4.8%.
"Among patients with atrial fibrillation deemed suitable for anticoagulation, a device-based left atrial appendage closure using the Watchman FLX (搜索) device was noninferior for the composite endpoint of stroke, systemic embolization, and cardiovascular death compared to NOAC therapy," reported lead investigator Saibal Kar, MD, from the Cardiovascular Institute of Los Robles Health System.
The device demonstrated statistically superior protection from non-procedural bleeding, with rates of 10.9% versus 19.0% for blood thinners, representing a 45% relative reduction in bleeding risk. However, when procedural bleeding was included, overall major bleeding rates were similar between groups at 5.9% for the device versus 6.4% for anticoagulation.
Safety Profile and Procedural Outcomes
The Watchman FLX (搜索) device was successfully implanted in 92.5% of patients randomized to the procedure arm, with a 99% procedural success rate. Effective closure of the left atrial appendage, defined as residual leak ≤3 mm, was achieved in 98.6% of patients at 4-month imaging.
Procedure-related serious adverse events occurred in 2.3% of patients, with pericardial effusions in 0.7%. Device-related thrombus was detected in 4.8% of imaged patients, with 1.8% requiring resumption of oral anticoagulation and two patients experiencing thrombus-related strokes.
Expert Concerns and Limitations
Despite meeting statistical endpoints, the trial faced significant criticism from leading cardiologists. Gregory Marcus, MD, from the University of California San Francisco, who authored an accompanying editorial, noted that observed event rates were much lower than those used to power the trial, making it easier to meet noninferiority criteria.
"The CLOSURE-AF study raises the burden of proof to demonstrate at worst equivalence, if not superiority, of the device, and I don't think that CHAMPION-AF convincingly provided that proof," Marcus stated, referencing a recent negative trial of left atrial appendage occlusion.
The trial showed more primary endpoint events in the device arm (81 vs 65), including more ischemic strokes (45 vs 27). Gregory Katz, MD, from NYU Langone Health, called the increased stroke rate "a pretty concerning endpoint," even though the finding was only borderline significant.
Sanjay Kaul, MD, from Cedars-Sinai, criticized the trial design, stating it was "a win on the scoreboard but a loss as far as delivering meaningful, reliable therapeutic value." He noted that the results "would have to be unequivocally positive to overcome the skeptical prior" evidence from previous trials.
Clinical Implications and Future Directions
The study population had a mean CHA2DS2-VASc score of 3.5 and HAS-BLED score of 1.3, with 68.9% having paroxysmal atrial fibrillation. Nearly half (47.8%) had undergone prior ablation for their arrhythmia, and 87% reported adherence to anticoagulation therapy during follow-up.
Benjamin Hibbert, MD, PhD, from Mayo Clinic, offered a more positive perspective: "This solidifies LAAO as an alternative to DOACs. Patients can now meet with their cardiologist and discuss the trade-offs of each strategy."
However, several experts emphasized the need for careful patient selection. Marcus suggested the procedure makes sense for patients with true contraindications to long-term anticoagulation or those with left atrial appendage thrombus, but questioned its use in patients eligible for blood thinners.
Market Impact and Regulatory Implications
Boston Scientific announced the results will support submissions for expanded indications and coverage for the Watchman platform as a first-line stroke reduction option. The company noted that 40% of atrial fibrillation patients prescribed blood thinners are not taking their medications consistently.
More than 600,000 people have been treated with Watchman devices since approval, with approximately 30,000 procedures performed annually in the United States. The WATCHMAN FLX (搜索) device was approved by the FDA in 2015, with the latest-generation FLX Pro device approved in 2023.
Patient follow-up will continue through five years, with stroke or systemic embolism as the primary endpoint. Additional trials including LAAOS-4 and CATALYST are ongoing to provide more data on high-risk populations and alternative devices.
The researchers concluded that "the use of left atrial appendage closure as a possible alternative to oral anticoagulation should be part of a shared decision-making process with patients who have atrial fibrillation," though the medical community remains divided on the appropriate patient population for this intervention.