Key Takeaways:
- The AMULET IDE trial compared the AMPLATZER Amulet occluder with the Watchman 2.5 device in patients with nonvalvular atrial fibrillation (NVAF) at high risk of thromboembolism.
- Patients with the Amulet occluder were significantly more likely to be free from oral anticoagulation (OAC) at 5 years compared with the Watchman device (94.0% vs. 90.9%, p = 0.009) and clinical outcomes, including rates of ischemic stroke or systemic embolism (7.4% vs. 7.1%, p = 0.851) and major bleeding (20.1% vs. 20.0%, p = 0.882), were similar between the devices.
- Strokes in the Amulet occluder group were less often fatal or disabling compared to the Watchman group (22 vs. 39 events, p = 0.030).
The left atrial appendage (LAA) is a key source of thromboembolism in patients with NVAF. Percutaneous LAA closure (LAAO) offers an alternative to OAC, reducing thromboembolic risks while avoiding bleeding complications associated with long-term OAC. The AMULET IDE trial (ClinicalTrials.gov identifier: NCT02879448) (AMPLATZER Amulet Left Atrial Appendage Occluder [LAAO] Investigational Device Exemption [IDE] Trial)evaluated the safety and effectiveness of the Amulet occluder (Abbott) in patients with nonvalvular atrial fibrillation. The Amulet IDE trial is the largest randomized LAAO trial, comparing the Amulet occluder with the Watchman 2.5 device (Boston Scientific).
The authors presented the 5-year results from the main trial comparing the 2 devices head to head at AHA 2024 with simultaneous publication in JACC.
The AMULET IDE trial was a prospective, multicenter, randomized study involving 1,878 patients across 109 sites globally. Participants were adults with paroxysmal, persistent, or permanent NVAF, and at high risk of stroke (CHA₂DS₂-VASc ≥3). Patients were randomized 1:1 to receive either the Amulet occluder or the Watchman device. Outcomes assessed included ischemic stroke, systemic embolism, cardiovascular (CV) death, and major bleeding.
A total of 1,833 patients underwent device implantation (917 with the Amulet and 916 with the Watchman). Follow-up rates exceeded 80% at 5 years. At 5 years, a significantly higher percentage of Amulet patients were free from OAC (94.0% vs. 90.9%, p = 0.009). Clinical outcomes were comparable between devices: 5-year difference in ischemic stroke or systemic embolism between patients who received Amulet devices versus patients who received Watchman devices was 0.3% (95% CI: 0.71-1.50, p=0.851), 5-year difference in major bleeding between patients who received Amulet devices versus patients who received Watchman devices was 0.1% (95% CI: 0.82-1.26, p=0.882), and 5-year difference in all-cause mortality between patients who received Amulet devices and patients who received Watchman was -2.4% (95% CI: 0.75-1.07, p=0.217). The Amulet occluder group experienced fewer fatal or disabling strokes (22 vs. 39 events, p = 0.030). Device-related factors, including thrombus and peridevice leaks ≥3 mm, were more frequent with the Watchman device (63 vs. 31 events).
The authors concluded, “Long-term clinical benefits of the Amulet occlude were sustained in the Amulet IDE trial through 5 years, thus allowing for reduction of atrial fibrillation-related thromboembolic events without the need for oral anticoagulation.” Future research may focus on real-world applicability and comparisons with newer-generation devices.