Boston Scientific Corporation has announced data supporting the use of the company’s Farapulse pulsed field ablation (PFA) platform and Watchman left atrial appendage closure (LAAC) technologies. All data were presented at the 2026 Heart Rhythm Society (HRS) annual meeting (23–26 April, Chicago, USA).
As detailed in a Boston Scientific press release, the randomised AVANT GUARD clinical trial met all safety and effectiveness endpoints, and demonstrated statistical superiority of PFA over antiarrhythmic drugs (AADs) with significantly higher primary effectiveness.
The trial is said to be the first randomised pivotal study to evaluate patients with persistent atrial fibrillation (AF) who had not previously been treated for their condition. Patients were randomised or assigned to receive pulmonary vein isolation (PVI) and left atrial posterior wall isolation (PWI) using the Farawave PFA catheter, or given AADs for treatment.
Results from AVANT GUARD were simultaneously published in the New England Journal of Medicine. In the trial, PFA achieved superiority over AADs with a primary effectiveness rate of 56% at 12 months compared to 30.1% in the AAD group. Additionally, the primary safety endpoint was met with a major adverse event rate of 5.1% at 12 months. Significantly more patients in the PFA group (51.7%) were free from atrial arrhythmia recurrence at 12 months, compared to in the AAD group (32.2%).
New PFA data
Findings from the single-arm ELEVATE-PF feasibility trial examining the safety and effectiveness of the Faraflex PFA catheter—a novel, high-density, large, focal map-and-ablate catheter designed to treat complex arrhythmias in patients with paroxysmal and persistent AF—were also presented at HRS 2026. According to Boston Scientific, the trial enables ongoing PFA dosing and workflow refinements based on a study design incorporating prospective high-density remapping, analysing patients sequentially in three groups: feasibility, improved and optimised.
A key finding from this ongoing trial included workflow improvements, as PVI durability—the permanence of an ablation lesion over time—increased from 80.4% on a per-vein basis in the feasibility group (n=13) to 96.4% in the optimised group (n=34). Within the optimised group, PVI durability in patients with persistent AF was 95.6% at two months (n=17). Furthermore, there were no reports of stroke, pulmonary vein stenosis, haemolysis or coronary spasm.
Additionally, prospective, interim, real-world evidence from ALIGN-AF—a multicentre sub-study of the DISRUPT-AF registry—reinforced that concomitant procedures combining the Farawave PFA catheter and the Watchman FLX Pro LAAC device could be performed safely without compromising acute procedural success. The study, which includes 122 patients at 12 sites with 24 physicians performing the procedures, assessed peri-device leaks between 45 and 90 days following implant, and will assess arrhythmia recurrence at six and 12 months.
As per available three-month data, ablation with the Farawave PFA catheter achieved a 100% (n=122/122) acute success rate. Ablation parameters, such as lesion sets and procedure duration, were consistent with those observed in standalone PFA procedures, according to Boston Scientific. Meanwhile, LAAC with the Watchman FLX Pro implant also achieved 100% (n=119/119) procedural success and 90.6% (n=96/106) complete LAA closure at a mean of 66 days with no clinically relevant leaks or device-related thrombus reported.
LAAC, S-ICD and more
Elsewhere at HRS 2026, a sub-analysis of the CHAMPION-AF trial studied LAAC therapy with the Watchman FLX implant compared to non-vitamin K antagonist oral anticoagulants (NOACs) in patients with and without prior ablation for non-valvular AF (NVAF). The analysis included 1,434 patients who had a cardiac ablation for AF prior to randomisation and 1,565 patients who did not have a previous ablation. The results highlighted that, for patients in both arms of the sub-analysis, the device provided statistically significant protection from non-procedural bleeding and had similar efficacy to NOACs.
The Watchman FLX device provided statistically significant protection from non-procedural bleeding, including major and clinically relevant non-major bleeding, compared to NOACs in patients who had a prior ablation (9% vs 17%) and in patients with no prior ablation (12.8% vs 20.8%). The Watchman FLX device also showed similar efficacy to NOACs for the occurrence of stroke, cardiovascular or unexplained death, or systemic embolism, regardless of whether they had a prior ablation—3.9% for both the device and NOACs in patients with prior ablation, and 7.5% for the device group versus 5.7% for the NOAC group in patients with no prior ablation.
Additionally, five-year follow-up data from the ASAP-TOO trial provided evidence on the legacy Watchman LAAC device (n=284) or the Watchman FLX LAAC device (n=20) compared to single antiplatelet therapy (SAPT) or no medication in reducing the risk of ischaemic stroke or systemic embolism in patients with NVAF who were deemed unsuitable for oral anticoagulation medication. According to Boston Scientific, while these findings contribute new clinical data on LAAC and stroke protection, interpretation is “limited”, as the trial ended early due to slow enrolment driven by physician preference for the device over SAPT or no medication—not safety-related factors—and variability in long-term follow-up.
Ultimately, however, ASAP-TOO saw a lower rate of occurrence of stroke or systemic embolism with an LAAC device compared to the control group (7.8% vs 11.4%), and LAAC therapy was associated with significantly fewer disabling strokes compared to the control group (1.1% vs 3.8%) as well. The device group also had a rate of 1% for all-cause death, ischaemic stroke, systemic embolism, or device- or procedure-related events requiring open cardiac surgery or major endovascular intervention within discharge or seven days.
Finally, results from the investigator-sponsored PRAETORIAN DFT study of Boston Scientific’s Emblem magnetic resonance imaging (MRI) subcutaneous implantable defibrillator (S-ICD) were also presented as a late-breaking clinical trial at HRS 2026, meeting the primary endpoint. Findings from the trial achieved non-inferiority in the likelihood of failed therapy when omitting defibrillation testing, as guided by the Praetorian score—an estimate of successful delivery of life-saving therapy—in patients receiving the device for the first time.
“The data presented at HRS 2026 reflect the continued momentum of our cardiovascular portfolio and underscore our commitment to advancing innovation through comprehensive clinical evidence across the spectrum of cardiac care,” said Kenneth Stein, senior vice president and global chief medical officer at Boston Scientific. “These findings support the potential expansion of our Farapulse PFA platform into more complex patient populations, highlight the value of a combined therapeutic approach with our Watchman FLX Pro LAAC device, may enhance the implant experience with the Emblem MRI S-ICD, and position us to deliver a broader portfolio of differentiated solutions for physicians treating patients with cardiovascular diseases.”
