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 annual meeting.
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 1,878 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 Dr. Lakkireddy, Kansas City Heart Rhythm Institute and Research Foundation, Overland Park, Kan.
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, Dr. 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, Dr. Lakkireddy said. DRT occurred in 1 patient with Amulet and 2 patients with Watchman and peridevice leak in 3 with Amulet and 15 with Watchman. “Again, the peridevice leak issue really stands out as an important factor,” he said at the meeting, which was sponsored by the Cardiovascular Research Foundation.
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).