Amulet, Watchman 2.5 LAAO Outcomes Neck and Neck at 3 Years

Patrice Wendling

September 21, 2022

The Amplatzer Amulet (Abbott) and first-generation Watchman 2.5 (Boston Scientific) devices provide relatively comparable results out to 3 years after left atrial appendage occlusion (LAAO), longer follow-up from the Amplatzer Amulet Left Atrial Appendage Occluder Versus Watchman Device for Stroke Prophylaxis (Amulet IDE) trial shows.

"The dual-seal Amplatzer Amulet left atrial appendage occluder continued to demonstrate safety and effectiveness through 3 years," principal investigator Dhanunjaya Lakkireddy, MD, said in a late-breaking session at the recent Transcatheter Cardiovascular Therapeutics (TCT) 2022.

Preliminary results, reported last year, showed that procedural complications were higher with the Amplatzer but that it provided superior closure of the left atrial appendage (LAA) at 45 days and was noninferior with respect to safety at 12 months and efficacy at 18 months.

Amulet IDE is the largest head-to-head comparison of the two devices, enrolling 1878 high-risk patients with nonvalvular atrial fibrillation undergoing LAA closure to reduce the risk of stroke.

Three-year follow-up was higher with the Amulet device than with the Watchman, at 721 vs 659 patients, driven by increased deaths (85 vs 63) and withdrawals (50 vs 23) in the Watchman group within 18 months, noted Lakkireddy, Kansas City Heart Rhythm Institute and Research Foundation, Overland Park, Kansas.

Use of oral anticoagulation was higher in the Watchman group at 6 months (2.8% vs 4.7%; P = .04), 18 months (3.1% vs 5.6%; P = .01), and 3 years (3.7% vs 7.3%; P < .01).

This was primarily driven by more late device-related thrombus (DRT) after 6 months with the Watchman device than with the Amulet occluder (23 vs 10). "Perhaps the dual-closure mechanism of the Amulet explains this fundamental difference, where you have a nice smooth disc that covers the ostium," he posited.

At 3 years, rates of cardiovascular death trended lower with Amulet than with Watchman (6.6% vs 8.5%; P = .14), as did all-cause deaths (14.6% vs 17.9%; P = .07).

Most cardiovascular deaths in the Amulet group were not preceded by a device factor, whereas DRT (1 vs 4) and peridevice leak 3 mm or more (5 vs 15) frequently preceded these deaths in the Watchman group, Lakkireddy observed. No pericardial effusion-related deaths occurred in either group.

Major bleeding, however, trended higher for the Amulet, at 16.1%, compared with 14.7% for the Watchman (P = .46). Ischemic stroke and systemic embolic rates also trended higher for Amulet, at 5%, and 4.6% for Watchman.

The protocol recommended aspirin only for both groups after 6 months. None of the 29 Amulet and 3 of the 29 Watchman patients with an ischemic stroke were on oral anticoagulation at the time of the stroke.

Device factors, however, frequently preceded ischemic strokes in the Watchman group, Lakkireddy said. DRT occurred in one patient with Amulet and two patients with Watchman and peridevice leak in three with Amulet and 15 with Watchman. "Again, the peridevice leak issue really stands out as an important factor."

Based on "data from the large trials, it's clearly evident that the presence of peridevice leak significantly raises the risk of stroke in follow-up," he said. "So, attention has to be paid to the choice of the device and how we can mitigate the risk of peridevice leaks in these patients."

The composite of stroke, systemic embolism, and cardiovascular death occurred in 11.1% of patients with Amulet and 12.7% with Watchman (P = .31).

Asked following the formal presentation whether the results justify use of one device over the other for LAA occlusion, Lakkireddy said he likes the dual closure mechanism of the Amulet and is more likely to use it in patients with proximal lobes, very large appendages, or a relatively shallow appendage. "In the rest of the cases, I think it's a toss-up."

As for how generalizable the results are, he noted that the study tested the Amulet against the legacy Watchman 2.5 but that the second-generation Watchman FLX is available in a larger size and has shown improved performance.

The Amplatzer Amulet does not require oral anticoagulants at discharge. However, the indication for the Watchman FLX was recently expanded to include 45-day dual antiplatelet therapy as a postprocedure alternative to oral anticoagulation plus aspirin.

Going forward, the "next evolution" is to test the Watchman FLX and Amulet on either single antiplatelet or a dual antiplatelet regimen without oral anticoagulation, he suggested.

Results from SWISS APERO, the first randomized trial to compare the Amulet and Watchman FLX (and a handful of 2.5 devices) in 221 patients, showed that the devices are not interchangeable for rates of complications or leaks.

During a press conference prior to the presentation, discussant Federico Asch, MD, MedStar Health Research Institute, Washington, DC, said, "the most exciting thing here is that we have good options. We now can start to tease out which patients will benefit best from one or the other because we actually have two options."

Transcatheter Cardiovascular Therapeutics (TCT) 2022. Presented September 17, 2022.

The Amulet IDE trial was funded by Abbott. Lakkireddy reports that he or his spouse/partner have received grant/research support from Abbott, AtriCure, Alta Thera, Medtronic, Biosense Webster, Biotronik, and Boston Scientific; and speaker honorarium from Abbott, Medtronic, Biotronik, and Boston Scientific.

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