Late-Breaking Study Results Reinforce Positive Real-World Outcomes With the WATCHMAN FLX™ LAAC Device

MARLBOROUGH, Mass., Feb. 28, 2022 – Boston Scientific Corporation announced positive results from a new analysis assessing real-world outcomes with the WATCHMAN FLX™ Left Atrial Appendage Closure (LAAC) Device. Presented during a late-breaking trial session at the Cardiovascular Research Technologies (CRT) 2022 meeting, the SURPASS analysis included data from more than 16,000 patients with non-valvular atrial fibrillation within the National Cardiovascular Data Registry (NCDR) Left Atrial Appendage Occlusion (LAAO) Registry.

The positive data demonstrated a low 0.37% rate of major adverse events at seven days following a WATCHMAN FLX implant or the time of hospital discharge, whichever was later. This key safety endpoint was defined as a composite of all-cause death, ischemic stroke, systemic embolism or device/procedure-related events requiring open cardiac surgery or major endovascular intervention. Additional outcomes measured at the 45-day follow up after a WATCHMAN FLX implant included a 0.51% rate of pericardial effusion requiring either surgical or percutaneous intervention, with only 0.03% of patients requiring cardiac surgery.

"This analysis includes the largest number of real-world WATCHMAN FLX patients to date and provides evidence that this stroke reduction therapy is associated with a low incidence of adverse events and peri-device leak through 45 days," said Dr. Samir Kapadia, chairman of the Robert and Suzanne Tomsich Department of Cardiovascular Medicine, Sydell and Arnold Miller Family Heart, Vascular & Thoracic Institute, Cleveland Clinic.* "SURPASS represents the experience of more than 2000 physicians using this therapy in routine clinical practice."

In the analysis, the WATCHMAN FLX device was successfully implanted in 97.6% of patients, and data also demonstrated low rates of ischemic stroke (0.28%) and device embolization (0.03%) in patients at 45 days. The SURPASS study is ongoing and will continue to collect outcomes through at least two years post-implant on all patients in the NCDR-LAAO Registry treated with WATCHMAN FLX between August 2020 and August 2022. The key effectiveness endpoint of occurrence of ischemic stroke or systemic embolism will be evaluated after 24 months.

"The strong safety and efficacy profile of the WATCHMAN FLX device demonstrated in the SURPASS analysis reinforces many of the safety and effectiveness results seen in the pivotal PINNACLE FLX trial, while representing a high-risk, real-world patient population and wide variety of patient anatomies," said Dr. Ian Meredith, global chief medical officer, Boston Scientific. "We look forward to further analyses from this large, representative study of patients with NVAF treated by physicians with a broad range of implanting experience."

The WATCHMAN technology has been implanted in more than 200,000 patients worldwide, with clinical research on the use of the WATCHMAN FLX device in patients with NVAF continuing via two large prospective, randomized controlled trials: the OPTION and CHAMPION-AF clinical studies.

For more information, visit www.watchman.com/implanter.

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*Dr. Samir Kapadia has not been compensated by Boston Scientific Corporation for his work on the SURPASS analysis or his quote within this news release.