Key result
Watchman FLX linked to ~3-fold higher device-related thrombosis reports vs. Amulet, which had more tamponade.
Why the study?
Comparative real-world safety data for the Watchman FLX/FLX Pro and Amplatzer Amulet left atrial appendage occlusion devices following FDA approval were limited.
Does the Watchman FLX/FLX Pro have a different post-market complication profile compared to the Amplatzer Amulet in FDA MAUDE adverse-event reports?
Observational (n=8,578)
Does the Watchman FLX/FLX Pro have a different post-market complication profile compared to the Amplatzer Amulet in FDA MAUDE adverse-event reports?
Post-market FDA surveillance reveals distinct complication profiles for contemporary LAAO devices, with Amplatzer Amulet disproportionately linked to acute mechanical/pericardial events and Watchman FLX/FLX Pro disproportionately linked to device-related thrombosis and thromboembolism.
MAUDE signals for Amulet complications warrant cautious interpretation; extends RCT safety data but should not yet change practice.
Background The Watchman FLX/FLX Pro (Boston Scientific) and Amplatzer Amulet (Abbott) are contemporary left atrial appendage occlusion (LAAO) devices, but comparative data on their real-world safety following FDA approval remain limited. Objective To compare the complication profiles of the two devices using disproportionality analysis of post-market adverse-event reports. Methods We analyzed FDA Manufacturer and User Facility Device Experience (MAUDE) reports involving Watchman FLX/FLX Pro and Amplatzer Amulet devices received between January 2021 and May 2026. After exclusion of literature-, registry-, and online-derived reports, 6,365 Watchman and 2,213 Amulet direct reports comprised the primary cohort. Complications were identified from narrative text, including a conservatively defined device-related thrombosis endpoint. Disproportionality was assessed using proportional reporting ratios (PRR) and reporting odds ratios (ROR), with the alternative device serving as comparator. Sensitivity analyses included date-matched, year-by-year, and device-size-stratified comparisons. Results The devices demonstrated distinct opposing complication profiles. Amulet reports were disproportionately associated with tamponade (PRR 2.94), device embolization (2.20), pericardial effusion (2.00), surgical intervention (2.28), and procedural death (2.33). In contrast, Watchman reports were disproportionately associated with device-related thrombosis (3.04) and thromboembolism (2.43). Directionally concordant ROR findings were observed for all endpoints. These signals persisted in date-matched analyses and across annual cohorts, supporting their temporal consistency. Conclusion In post-market MAUDE reporting, Amulet was disproportionately associated with acute pericardial and mechanical complications, whereas Watchman FLX/FLX Pro was disproportionately associated with device-related thrombosis and thromboembolic events. These findings are broadly concordant with randomized evidence and provide hypothesis-generating comparative safety signals, although disproportionality analyses cannot estimate incidence.
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Abdelsayed et al. (2026) conducted an observational in Left atrial appendage occlusion (LAAO) (n=8,578). Watchman FLX/FLX Pro vs. Amplatzer Amulet was evaluated on Device-related thrombosis and post-market complications (tamponade, device embolization, pericardial effusion, surgical intervention, procedural death, thromboembolism) (PRR 3.04 for device-related thrombosis (Watchman vs Amulet); PRR 2.94 for tamponade (Amulet vs Watchman)). Watchman FLX/FLX Pro had higher reporting of device-related thrombosis (PRR 3.04), whereas Amplatzer Amulet had higher reporting of tamponade (PRR 2.94) and procedural death (PRR 2.33).
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