Amulet device better at LAA closure, noninferior for safety, effectiveness vs. Watchman
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In a head-to-head comparison of two left atrial appendage closure devices for patients with atrial fibrillation, the Amplatzer Amulet device was superior at closure and noninferior for safety and effectiveness vs. the Watchman device.
Results of the Amulet IDE trial, presented at the European Society of Cardiology Congress, supported the recent FDA approval of the Amplatzer Amulet device (Abbott).
Unlike with the Watchman device (Boston Scientific), oral anticoagulation is not required after use of the Amulet device, Dhanunjaya R. Lakkireddy, MD, FHRS, medical director of the Kansas City Heart Rhythm Institute at HCA Midwest Health in Overland, Kansas, said during a press conference.
“The Watchman is a single-closure, mushroom-looking device, whereas the Amulet device has a dual closure mechanism with an inner lobe and hooks that engage with the left atrial appendage wall connected to an outer disc with a small waist,” Lakkireddy said. “The outer disc is relatively large, wide and circular, and has the ability to close larger ostia and also covers more proximal lobes that would be otherwise difficult to close.”
Lakkireddy and colleagues randomly assigned 1,878 patients with nonvalvular AF (mean age, 75 years; 60% men) at high risk for stroke (CHADS2 score of at least 2 or CHA2DS2-VASc score of at least 3) to receive LAA closure with the Amulet or Watchman devices.
Implant success rate was 98.4% in the Amulet group and 96.4% in the Watchman group. Twenty-one percent of patients were discharged on oral anticoagulation in the Amulet group compared with 95.8% in the Watchman group, according to the presentation.
The mechanism of action primary endpoint, residual jet of 5 mm or less at 45 days, favored the Amulet group (98.9% vs. 96.8%; difference, 2.03%; P for noninferiority < .0001; P for superiority = .0025), Lakkireddy said.
In a post hoc analysis, residual jet of 3 mm or less at 45 days also favored the Amulet group (89.8% vs. 75.1%; P for superiority < .0001), according to the presentation.
The primary safety endpoint of procedure-related complications, all-cause death or major bleeding at 12 months was similar in both groups (Amulet, 14.5%; Watchman, 14.7%; difference, –0.14%; P for noninferiority = .0002), Lakkireddy said.
However, procedure-related complications were higher in the Amulet group (4.5% vs. 2.5%), driven by pericardial effusion (2.4% vs. 1.2%) and device embolization (0.7% vs. 0.2%), but procedure-related complications with the Amulet device decreased with increasing operator experience.
“Each individual [Amulet] operator was given an option of having three cases as a roll-in,” Lakkireddy said. “They were subsequently allowed to do these procedures on their own. There was a slightly higher rate of complications in the Amulet arm, and this particular phenomenon corrected itself very quickly once the operators gained enough experience.”
The primary effectiveness endpoint, defined as ischemic stroke or systemic embolism at 18 months, was 2.8% in both groups (difference, 0%; P for noninferiority < .0001), Lakkireddy said.
The secondary endpoint of stroke, systemic embolism and CV death at 18 months did not differ between the groups (Amulet, 5.6%; Watchman, 7.7%; P for noninferiority < .0001), nor did the secondary endpoint of major bleeding at 18 months (Amulet, 11.6%; Watchman, 12.3%), according to the presentation.
“It is fair to say that the impact on clinical practice is that the Amulet left atrial appendage occluder can safely and effectively treat more nonvalvular atrial fibrillation patients ... without needing oral anticoagulation,” Lakkireddy said. “Its immediate closure to reduce the risk of stroke and immediate freedom from oral anticoagulation could be attractive. It also gives confidence that a device to reduce the risk of stroke can allow you to safely stop oral anticoagulation medication.”
Reference:
Perspective
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Vivek Y. Reddy, MD
Overall, the Amulet device performed quite favorably compared to the traditional Watchman device. The peri-device leak rate was actually lower with the Amulet device than Watchman. Also, despite an arguably less-intense post-implant antithrombotic regimen (ie, most patients assigned Amulet received dual antiplatelet therapy for the initial few months, while patients assigned Watchman largely received oral anticoagulation), the device-related thrombus rate was not higher with Amulet; it was numerically lower, though not statistically significant. All of this is favorable. I was also struck with the fact the annualized ischemic stroke rate in both groups was only approximately 1.7-1.8% based on the 18-month rates). Obviously, there was no control group, but given a CHA2DS2-Vasc population of approximately 4.5-4.7, these are actually very low rates.
On the other hand, the pericardial effusion rate was substantially higher with Amulet (2.4 vs 1.2%), as was the device embolization rate (0.7 vs 0.2%) but of course, for the vast majority of the operators in this trial, they had never before performed an Amulet device implantation beforehand. So I do imagine that just as these complication rates decreased substantially with even just a little clinical experience with Watchman implantation, so too with the Amulet device as it is elaborated in clinical practice.
The other major issue is that, starting last year, in the U.S. and the rest of the world, the Watchman device has been replaced by the Watchman-FLX device, which is clearly a better device in terms of ease of implantation, safety, less device-related thrombus, less leak, etc., as demonstrated in the PINNACLE-FLX trial (Kar S, et al. Circulation. 2021;doi:10.1161/CIRCULATIONAHA.120.050117).
Probably for the majority of patients, both devices are similar in outcomes, but for a few anatomies, one device may be slightly better than the other.
Certainly, a comparison of Amulet with Watchman-FLX would be interesting. But the most important trials are ongoing. CATALYST and CHAMPION-AF are each comparing an LAA closure device (Amulet or Watchman-FLX) to non-vitamin K antagonist oral anticoagulants, but it will be a few years before these are done enrolling.
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Lakkireddy DR, et al. Hot Line: Amulet IDE. Presented at: European Society of Cardiology Congress; Aug. 27-30, 2021 (virtual meeting).
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