Related Experiment Video
Updated: May 15, 2025
The WATCHMAN Left Atrial Appendage Closure Device for Atrial Fibrillation
Published on: February 28, 2012
Characterization and Clinical Outcomes of High-Risk Device-Related Thrombus in the Amulet IDE Trial
Jens Erik Nielsen-Kudsk1, Boris Schmidt2, Stephan Windecker3
1Aarhus University Hospital, Aarhus, Denmark.
Insights
Device-related thrombus (DRT) characteristics impact clinical outcomes. High-risk DRTs, more common with the Watchman 2.5 device, were linked to increased stroke, embolism, and cardiovascular death risks compared to low-risk DRTs or no DRTs.
Area of Science:
- Cardiology
- Medical Devices
- Thrombosis
Background:
- Device-related thrombus (DRT) characteristics can vary between left atrial appendage occlusion (LAAO) devices.
- The clinical impact of different DRT characteristics remains poorly understood.
Purpose of the Study:
- To assess the incidence, characteristics, and 5-year clinical outcomes of high-risk and low-risk DRTs within the Amulet IDE trial.
- To compare DRT occurrence and outcomes between the Amulet and Watchman 2.5 LAAO devices.
Main Methods:
- Independent core laboratory analysis of imaging at 45-day and 12-month visits.
- Clinical event reporting for up to 5 years post-LAAO procedure.
- Classification of DRTs as high-risk based on morphology (pedunculated, mobile, >3mm thickness, or non-continuous with atrial wall).
Main Results:
- DRT incidence was 3.3% for Amulet and 4.5% for Watchman 2.5 at 12 months (P=0.192).
- High-risk DRTs were significantly more frequent with Watchman 2.5 (4.0%) than Amulet (2.2%) (P=0.030).
- High-risk DRTs persisted, while most low-risk DRTs resolved. Patients with high-risk DRTs had higher rates of stroke, systemic embolism, or cardiovascular death (30.4% vs 19.9%; P=0.037) and cardiovascular death (26.4% vs 14.5%; P=0.009) over 5 years.
Conclusions:
- High-risk DRTs occurred more often in Watchman 2.5 patients compared to Amulet patients.
- The composite outcome of stroke, systemic embolism, or cardiovascular death was more frequent in patients with high-risk DRTs.
- These findings highlight the clinical significance of DRT characteristics following LAAO procedures.
Background:
Characteristics of device-related thrombus (DRT) may differ between types of left atrial appendage occlusion 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 (AMPLATZER Amulet Left Atrial Appendage Occluder [LAAO] Investigational Device Exemption [IDE] Trial).
Methods:
An independent core laboratory analyzed all available images at the required 45-day and 12-month visits, and clinical events were reported through 5 years' post-left atrial appendage occlusion.
Results:
Of the 1,788 patients with a successful device implant, DRT was observed in 3.3% (30 of 903) and 4.5% (40 of 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 of 885]) compared with the Amulet occluder (2.2% [20 of 903]) (P = 0.030). Most low-risk DRTs resolved (12 of 15), whereas high-risk DRTs remained mostly unresolved (34 of 55). Through 5 years, all clinical outcome rates were numerically higher in the high-risk DRT group compared with the low-risk DRT or no-DRT group; significance was observed in the composite of stroke, systemic embolism, or cardiovascular death (30.4% vs 19.9%; HR: 1.74; 95% CI: 1.03-2.92; P = 0.037) and cardiovascular death (26.4% vs 14.5%, HR: 2.09; 95% CI: 1.20-3.66; P = 0.009).
Conclusions:
High-risk DRTs were observed in a higher number of Watchman 2.5 device patients compared with Amulet occluder patients. The composite of stroke, systemic embolism, or cardiovascular death occurred more often in patients with high-risk DRTs compared with those with low-risk DRTs or no DRTs. (AMPLATZER Amulet Left Atrial Appendage Occluder [LAAO] Investigational Device Exemption [Amulet IDE Trial]; NCT02879448).
