Among patients at high risk of stroke or systemic embolism, the AMPLATZER Amulet left atrial appendage (LAA) occluder was as safe and effective as the Watchman 2.5 device at five-year follow-up, according to results from the Amulet IDE trial, presented at AHA 2024 and simultaneously published in JACC. Additionally, patients with the Amulet occluder were less likely to suffer severe strokes or have device factors (either device-related thrombus or peri-device leak ≥3mm) preceding stroke events and cardiovascular deaths.

Investigators randomized at a 1:1 ratio 1,878 patients (average age 75; 40% women) with a CHADS2 score of ≥2 or CHA2DS2-VASc score of ≥3 (average score 4.6) to either the Amulet occluder (917) or the Watchman device (916). Among patients, the average HAS-BLED score was 3.3; 27% had history of a thromboembolic event, and 75% had a bleeding-associated concern.

Results showed that, after five years, annualized ischemic stroke rates were low – at 1.6% per year for both devices. Other clinical outcomes remained similar between the two, including a composite of ischemic stroke or systemic embolism (the primary effectiveness endpoint); composite of stroke, systemic embolism or cardiovascular death; major bleeding; cardiovascular death; and all-cause death.

Strokes among patients with the Amulet occluder were less severe (11 fatal, 11 disabling, 38 nondisabling, 12 unknown) than with the Watchman (17 fatal, 22 disabling, 19 nondisabling, 10 unknown), and device factors preceded stroke events and cardiovascular deaths more frequently among patients with the Watchman (63 patients) than the Amulet occluder (31 patients).

A higher percentage of patients with the Amulet occluder were free of oral anticoagulation (OAC) at five years compared to those with the Watchman (94.0% vs. 90.9%; p=0.009). At discharge, 78.9% of patients with the Amulet occluder had been immediately free of OAC vs. 4.2% of patients with the Watchman device (p<0.01), and there were a higher percentage of patients off OAC in the Amulet group than the Watchman group at all time points (p<0.05).

"With a [LAA occlusion (LAAO)] therapy goal of stroke prophylaxis without the need for OAC, the Amulet occluder allowed a high percentage of patients to remove OAC medications immediately and maintain freedom through 5 years," study authors Dhanunjaya R. Lakkireddy, MBBS, FACC, and colleagues write. They add, "Patients with the Watchman device were on OAC more often than patients with the Amulet occluder resulting in potentially more severe strokes."

In a related editorial comment, Daniel J. Friedman, MD, FACC, and James V. Freeman, MD, FACC, write, "The results from the Amulet IDE [trial] are reassuring that the available devices in the U.S. both offer consistent and excellent efficacy with acceptable safety. Additionally, these data suggest that the next most important frontier for improving the net clinical benefit of percutaneous LAAO is determining the optimal post-implant antithrombotic regimen."