Background: Device-related thrombus (DRT) characteristics may differ between types of left atrial appendage occlusion (LAAO) devices and the association of different DRT characteristics to clinical outcomes is largely unknown.
Objectives: The incidence, characteristics, and clinical outcomes through 5 years of High- and Low-Risk DRTs were assessed in the Amulet IDE trial.
Methods: An independent core lab analyzed all available images at the required 45-day and 12-month visits and clinical events were reported through 5 years post-LAAO.
Results: Of 1788 patients with a successful device implant, DRT was observed in 3.3% (30/903) and 4.5% (40/885) of Amulet and Watchman 2.5 device patients throughout 12 months, respectively (p=0.192). DRTs were successfully classified as High-Risk if pedunculated, mobile, >3 mm in thickness, or without continuation onto the left atrial wall. A significantly higher incidence of High-Risk DRTs was observed on the Watchman 2.5 device (4.0%; 35/885) compared to the Amulet occluder (2.2%; 20/903) (p=0.030). Most Low-Risk DRTs resolved (n=12 of 15) whereas High-Risk DRTs remained mostly unresolved (n=34 of 55). Through 5 years, all clinical outcome rates were numerically higher in the High-Risk DRT compared to the Low-Risk DRT or No-DRT group with significance observed in the composite of stroke, systemic embolism, or cardiovascular (CV) death (30.4% vs. 19.9%, HR: 1.74 [1.03, 2.92]; p=0.037) and CV death (26.4% vs. 14.5%, HR: 2.09 [1.20, 3.66]; p=0.009).
Conclusions: High-Risk DRTs were observed on a higher number of Watchman 2.5 device patients compared to Amulet occluder patients. The composite of stroke, systemic embolism, or cardiovascular death occurred more often in patients with High-Risk DRTs compared to those with Low-Risk DRT or No-DRT.
Editor-in-Chief
Kalyanam Shivkumar, MD, PhD, FACC
CME Editor
Kenneth A. Ellenbogen, MD, FACC
Author
Kelvin Bush, MD, FACC
Important Dates
Date of Release: July 28, 2025
Term of Approval/Date of CME/MOC Expiration: July 27, 2026