Amplatzer™ Cardiac Plug and Amulet
Amplatzer Cardiac Plug (ACP) and its second generation Amplatzer Amulet (St. Jude Medical, St Paul, MN, USA) are self-expanding devices made from nitinol mesh that consist of a proximal left atrial disk and a distal LAA lobe connected by a central waist (Figure 1).[24,25] The lobe has hooks for retention, and the disc is designed to seal the cavity in a fashion similar to a pacifier. The second generation Amulet has a wider lobe and more stabilization wires, which is designed to improve device stability. Implantation of ACP requires depth of 10 mm, while Amulet requires 12–15 mm.
The efficacy and safety of ACP have been evaluated in several non-randomized multicentre registries. Many registries included patients with relative or absolute contraindication to oral anticoagulation; hence, patients were treated with aspirin, Clopidogrel, or both, instead of periprocedural anticoagulation with warfarin. Data regarding safety and efficacy from some of the studies are summarized in Table 2. These observational studies demonstrated favourable outcomes with ACP, showing reduction in stroke risk than would have been predicted based on patient characteristics.[27–29] In a large registry of 1047 patients, Tzikas et al. reported a procedural success rate of 97.2% with a perioperative major adverse event rate of 4.1% (mortality 0.6%, cardiac tamponade 1.2%, device embolization 0.2%, and stroke 0.7%). Annual rate of stroke or systemic embolism was 2.3%, which was 59% lower predicted stroke risk; a similar reduction in stroke risk with LAAO with ACP was observed in other registries.[27–30] The annual rate of major bleeding was 2.1%, which was 61% lower than predicted by their HAS-BLED scores.
Although ACP and Amulet have not been fully evaluated in an RCT, a non-inferiority trial comparing Amplatzer Amulet to the Watchman device is currently undergoing enrolment (ClinicalTrials.gov number, NCT02879448). Although inclusion criteria for the Amulet IDE study specifies that patients be suitable for short-term anticoagulation, the study protocol does not mandate oral anticoagulation post-procedure in those patients randomized to Amulet, whereas those patients randomized to Watchman are mandated by study protocol to receive at least 45 days of warfarin. The lack of mandated post-procedural oral anticoagulation for the Amulet device will represent the first prospective RCT for which some form of oral anticoagulation is not required after implantation of an endocardial LAAO device, and data will be forthcoming regarding specific thrombotic risks associated with this strategy. The Amulet device received CE-mark in 2008 and is widely used in Europe. The device has yet to receive FDA approval.
Europace. 2018;20(9):1412-1419. © 2018 Oxford University Press
Copyright 2007 European Heart Rhythm Association of the European Society of Cardiology (ESC). Published by Oxford University Press. All rights reserved.