Comparison of Amulet vs Watchman/FLX Devices in Patients Undergoing Left Atrial Appendage Closure - SWISS-APERO

Contribution To Literature:

The SWISS-APERO trial showed that Amulet is not superior to Watchman for LAA patency (assessed by CCTA) at 45 days among patients undergoing percutaneous LAAC.


The goal of the trial was to demonstrate the superiority of Amulet compared with Watchman FLX for patients undergoing left atrial appendage closure (LAAC).

Study Design

All patients were randomized in a 1:1 open-label fashion to LAAC with either Amulet (n = 111) or Watchman (n = 110).

Patients randomized to the Watchman group before October 2019 received Watchman 2.5 (22.7%), whereas all patients randomized to the Watchman group after October 2019, received Watchman FLX.

  • Total number screened: 423
  • Total number of enrollees: 221
  • Duration of follow-up: 45 days
  • Mean patient age: 76.9 years
  • Percentage female: 29.4%

Inclusion criteria:

  • Nonvalvular atrial fibrillation
  • Clinical indication for LAAC
  • Age ≥18 years
  • CHA2DS2-VASc score ≥2 and either HAS-BLED score ≥3 or presence of high bleeding risk features
  • LAA anatomy suitable for both devices

Exclusion criteria:

  • LAA thrombus
  • Creatinine clearance <30 ml/min
  • Enrollment in another cardiovascular device or investigational drug trial

Other salient features/characteristics:

  • HAS-BLED score: 3.2
  • Need for dual antiplatelet therapy due to coronary artery disease/stenting: 13%
  • On oral anticoagulation monotherapy: 36%

Principal Findings:

The primary outcome, LAA patency on coronary computed tomography angiography (CCTA) at 45 days for Amulet vs. Watchman FLX, was: 67.6% vs. 70% (p = 0.71).

  • Intradevice leak: 44.8% vs. 23% (p = 0.001)
  • Mixed leaks: 3.8% vs. 14% (p = 0.01)

Secondary outcomes for Amulet vs. Watchman FLX:

  • Transesophageal echocardiography (TEE)-defined peridevice leak (>5 mm): 13.7% vs. 27.5% (p = 0.02)
  • Definite device-related thrombosis: 0.9% vs. 3.0% (p = 0.29); definite or probable device-related thrombosis: 3.7% vs. 9.9% (p = 0.076)
  • Major procedure-related complications: 9.0% vs. 2.7% (p = 0.047), major bleeding: 7.2% vs. 1.8% (p = 0.05), clinically relevant pericardial effusion: 3.6% vs. 0% (p = 0.12)
  • Cardiovascular disease/stroke/systemic embolism: 2.7% vs. 4.5%
  • 45-day death: 1.8% vs. 0% (p = 0.5; all periprocedural)


The results of this trial indicate that Amulet is not superior to Watchman for LAA patency (assessed by CCTA) at 45 days among patients undergoing percutaneous LAAC. Peridevice leaks were higher with Watchman on CTA and TEE, while intradevice leaks were higher with Amulet on CTA, although some of these could improve over time as the device endothelializes. Use of the Amulet device resulted in higher procedural complications, including major bleeding and pericardial effusions. A similar higher complication risk was noted in the Amulet IDE trial.

Results are interesting and add to the available literature comparing the two devices for percutaneous LAAC.


Galea R, De Marco F, Meneveau N, et al. Amulet or Watchman Device for Percutaneous Left Atrial Appendage Closure: Primary Results of the SWISS-APERO Randomized Clinical Trial. Circulation 2021;Nov 6:[Epub ahead of print].

Presented by Dr. Roberto Galea at the Transcatheter Cardiovascular Therapeutics (TCT) Conference, Orlando, FL, November 6, 2021.

Clinical Topics: Anticoagulation Management, Arrhythmias and Clinical EP, Cardiac Surgery, Cardiovascular Care Team, Geriatric Cardiology, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Pericardial Disease, Prevention, Anticoagulation Management and Atrial Fibrillation, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Cardiac Surgery and Arrhythmias, Interventions and Imaging, Angiography, Computed Tomography, Echocardiography/Ultrasound, Nuclear Imaging

Keywords: Anticoagulants, Arrhythmias, Cardiac, Atrial Appendage, Atrial Fibrillation, Cardiac Surgical Procedures, Computed Tomography Angiography, Coronary Angiography, Diagnostic Imaging, Echocardiography, Transesophageal, Embolism, Geriatrics, Hemorrhage, Pericardial Effusion, Secondary Prevention, Stroke, TCT21, Thrombosis, Transcatheter Cardiovascular Therapeutics, Vascular Diseases

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