The largest study of WATCHMAN FLX patients to date found that left atrial appendage (LAA) closure with the device was associated with low 45-day adverse event rates and peri-device leaks. The latest registry analysis of the real-world observational WATCHMAN FLX Device SURveillance Post Approval AnalySiS Plan (SURPASS) study were presented Monday in a late-breaking session at Cardiovascular Research Technologies (CRT) 2022 in Washington, D.C., by Samir R. Kapadia, MD, of the Cleveland Clinic. SURPASS acquired data from the U.S. National Cardiovascular Data Registry (NCDR) left atrial appendage occlusion (LAAO) Registry and includes consecutive patients who had a WATCHMAN FLX (Boston Scientific) implant attempt between September 2020 and March 2021. Increased thromboembolic stroke risk and history of major bleeding were the main indications for LAA occlusion. Registry data will be collected through 2 years post-implant via the LAAO Registry, the researchers noted in a study extract, with a plan for longer-term follow-up via linkage to claims data from the Centers for Medicare and Medicaid Services (CMS). The study had enrolled 16,646 patients as of March 2021, 14,363 of whom had 45 ± 14 days’ follow-up. The SURPASS patients had a mean age of 76 ± 8 years at enrollment, 40.3% were female, and 94.2% of them were white. The mean procedure time – counted from when the patient enters the procedure location until the time when the operator breaks scrub at the end of the procedure – was 81 ± 42 minutes, and the mean number of WATCHMAN FLX Left Atrial Appendage Closure (LAAC) devices used was 1.2 ± 0.4. SURPASS’ safety endpoints were a composite of all-cause death, ischemic stroke, systemic embolism, or device/procedure-related events requiring open cardiac surgery or major endovascular intervention between device implantation and 7 days or hospital discharge (whichever is later). The key efficacy endpoint was occurrence of ischemic stroke or systemic embolism at 24 months post-implant. Successful implantation (defined as device release and deployed) occurred in 98% of patients. Of the 16,048 patients, 0.37% (60 patients – of whom 21 died, 19 had ischemic stroke and 20 had events requiring intervention) hit the key safety endpoint (95% confidence interval [CI]: 0.29% to 0.48%). Key clinical events at discharge included 11 deaths (0.07%), 15 cases of stroke (0.09%), 157 cases of major bleeding (0.98%), 19 incidents of major vascular complications (0.12%), eight patients with device-related thrombus (0.05%) and two with device embolization (0.01%). At 45 days, 508 had major bleeding (3.55%), 125 patients had died (0.91%), 54 had suffered stroke (0.38%), one had systemic embolism (0.01%), 30 had device-related thrombus (0.23%) and five device-related embolization (0.03%). Peri-device leak >5 mm was 0.4% at 45 days, the researchers added in the abstract. LAA closure assessment at 45 days showed 82% had no leaks. In the abstract, the researchers also noted that the mean CHA2DS2-VASc score was 4.8 ± 1.51 and HAS-BLED score was 2.4 ± 1.01. The results were similar to those of the real-world PINNACLE FLX study for the same device, Kapadia noted. “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 Ian T. Meredith, AM, the global chief medical officer of Boston Scientific, in an accompanying press statement. “We look forward to further analyses from this large, representative study of patients with [non-valvular atrial fibrillation] treated by physicians with a broad range of implanting experience.”