5-Year Results From the AMPLATZER Amulet Left Atrial Appendage Occluder Randomized Controlled Trial

The Amulet IDE trial (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).

This analysis presents the 5-year results from the trial comparing the 2 devices head to head.

Patients enrolled in the Amulet IDE trial were at a high risk of stroke or systemic embolism defined as a CHADS₂ score ≥2 or CHA₂DS₂-VASc score ≥3. Oral anticoagulation (OAC) use and key clinical outcomes are presented through 5 years.

A total of 1,878 patients were randomized, with 1,833 undergoing a device implantation attempt (n = 917, Amulet occluder; and n = 916, Watchman device). A significantly higher percentage of patients were free of OAC in the Amulet occluder group at each follow-up visit, with 94.0% and 90.9% free of OAC at the last 5-year follow-up visit in the Amulet and Watchman device groups, respectively (P = 0.009). The 5-year clinical outcomes were similar between the Amulet and Watchman devices, including the composite of ischemic stroke or systemic embolism (7.4% vs 7.1%; P = 0.851), the composite of stroke, systemic embolism, or cardiovascular death (20.3% vs 20.7%; P = 0.666), major bleeding (20.1% vs 20.0%; P = 0.882), cardiovascular (CV) death (14.3% vs 15.4%; P = 0.429), and all-cause death (28.7% vs 31.1%; P = 0.217). Annualized ischemic stroke rates at 5 years were low and the same for Amulet (1.6%/y) and Watchman (1.6%/y) devices. Strokes in patients with the Amulet occluder were less severe (n = 38, nondisabling; n = 11, disabling; n = 11, fatal; n = 12, unknown) than strokes in patients with the Watchman device (n = 19, nondisabling; n = 22, disabling; n = 17, fatal; n = 10, unknown). Moreover, device factors (device-related thrombus or peridevice leak ≥3 mm) preceded stroke events and CV deaths more frequently in patients with the Watchman device (n = 63) compared with patients with the Amulet occluder (n = 31).

The 5-year outcomes from the largest randomized LAAO clinical trial demonstrated the long-term safety and effectiveness of the Amulet occluder and Watchman 2.5 devices. The dual-seal Amulet occluder reduces atrial fibrillation-related thromboembolic events while eliminating the need for long-term OAC. (AMPLATZER Amulet Left Atrial Appendage Occluder [LAAO] Investigational Device Exemption [IDE] Trial [Amulet IDE trial]; NCT02879448).