The Amulet IDE Trial is the first trial to offer a head-to-head comparison of the Amplatzer Amulet occluder from Abbot against the Watchman device from Boston Scientific for left atrial appendage occlusion.
Results of the Amulet IDE trial suggest the Amplatzer Amulet Left Atrial Appendage Occluder demonstrated superior left atrial appendage (LAA) closure and noninferior safety and effectiveness for stroke prevention in patients with nonvalvular atrial fibrillation compared to the Watchman device.
Presented during as part of a late-breaking session at the European Society of Cardiology (ESC) Congress 2021, the head-to-head trial provides clinicians with insights into results seen with the devices from Abbott and Boston Scientific as the popularity of LAA procedures continues to grow.
"Atrial fibrillation cases have increased in recent years as the world continues to age, making stroke risk more prevalent and resulting in higher usage of blood-thinning medication that can lead to bleeding and other complications," said principal investigator Dhanunjaya Lakkireddy, MD, Kansas City Heart Rhythm Institute at HCA Midwest Health, in a statement from Abbott. “Amulet demonstrated a clear benefit for people suffering from atrial fibrillation who are at risk of stroke and in need of LAA occlusion. The Amulet IDE trial data show that we can effectively treat these patients with Amulet and get them off blood thinners immediately following implantation."
With an interest in comparing the Amplatzer Amulet occluder against the Watchman occluder, Amulet IDE was designed as a multicenter randomized trial in patients 18 years of age or older with paroxysmal, persistent, or permanent nonvalvular atrial fibrillation, and at a high risk of stroke or systemic embolism. The trial was designed with a trio of primary endpoints, including a composite safety end point of procedure-related complications, all-cause death, or major bleeding at 12 months, a composite efficacy end point of ischemic stroke or systemic embolism at 18 months, and an additional end point assessing the rate of LAA occlusion at 45 days. Of note, the trial was sponsored by Abbott who was responsible for the design as well as selecting the monitoring sites.
A total of 2592 patients were screened for eligibility at 108 centers in the US and abroad from September 2016-March 2019. A cohort of 1878 was randomly assigned to receive an Amulet occluder or a Watchman device. In total, 934 patients were randomized to the Amulet occluder and 944 were randomized to the Watchman device.
Upon analysis, results indicated the Amulet occluder was noninferior to the Watchman device for the composite safety endpoint, with a primary safety event occurring among 14.5% of the Amulet occluder group and 14.7% in the Watchman group (difference=—.14 [95% CI, —3.42 to 3.13]; P <.001 for noninferiority). Further analysis revealed major bleeding (10.6% vs 10.0%) and all-cause mortality (3.9% vs 5.1%) were similar between those in the Amulet occluder and Watchman groups.
When assessing the primary efficacy end point, results suggested the Amulet occluder was noninferior to the watchman device and for a composite end point of stroke, systemic embolism, or cardiovascular/unexplained death (5.6% vs 7.7%; difference=—2.12 [95% CI, —4.45 to 0.21]; P <.001 for noninferiority). Results also indicated the rate of major bleeding was similar between the groups, with a. Rate of 11.6% among the Amulet occluder group and 12.3% among the Watchman device group (difference=—0.71 [95% CI, —3.72 to 2.31]; P=.32 for superiority). When assessing rates of occlusion at 45 days, results suggested occlusion was higher for the Amulet occluder group compared to the Watchman device group (98.9% vs 96.8%; difference=2.03 [95% CI, 0.41 to 3.66]; P <.001 for noninferiority; P=.003 for superiority).
“The Amulet LAA occluder was superior with respect to LAA closure and noninferior with respect to safety and effectiveness for stroke prevention in patients with NVAF compared to the Watchman device,” Lakkireddy added in a statement from the ESC.
"The dual seal design of the Amulet LAA occluder helps to overcome the limitations of a single seal device, including but not limited to short LAA length, proximal lobes near the ostium, and very large ostia. In addition, immediate closure of the LAA with the Amulet disc allows some patients to be treated without the need for anticoagulation therapy after the procedure.”
This study was presented as “Amulet IDE: Amplatzer Amulet left atrial appendage occluder randomized controlled trial,” at ESC Congress 2021 and simultaneously published as “Amplatzer Amulet Left Atrial Appendage Occluder Versus Watchman Device for Stroke Prophylaxis (Amulet IDE): A Randomized Clinical Trial,” in Circulation.