Reviewer: Dr. Arda Güler

Name of the study: Comparison of Amulet vs Watchman/FLX Devices in Patients Undergoing Left Atrial Appendage Closure (SWISS-APERO)

Published Congress: TCT-2021

Link: https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.121.057859

Background
Although oral anticoagulant (OAC) drugs are used to reduce the risk of thromboembolism in patients with non-valvular atrial fibrillation (NVAF), bleeding complications that may develop due to these drugs cause a vital safety problem. Percutaneous left atrial appendage closure (LAAC) is used to reduce thromboembolic risk in patients who cannot use OACs because of the high risk of bleeding. Many systems are used in the LAAC process, and the most commonly used are the Watchman™ system (Boston Scientific) and Amplatzer Amulet (St. Jude Medical-Abbott). However, no studies are comparing these devices in terms of effectiveness and safety. This study was planned to evaluate the LAA patency by cardiac computed tomography angiography (CCTA) evaluation on the 45th day after the LAAC procedure performed with these two devices.

Objective
This study aims to investigate the superiority of the Amulet device over the Watchman FLX in terms of efficacy and safety in patients undergoing LAAC by 45th-day CCTA evaluation.

Methods
A total of 221 patients were included in the study between June 2018 and May 2021, and patients were randomized 1:1 to the Amulet and the Watchman FLX groups. LAAC was performed with pre-procedural CT evaluation and intraoperative echocardiography. LAA thrombus assessment was routinely performed in two groups. Patients were evaluated with TEE and CCTA on the 45th day and CCTA alone at 13 months after successful LAAC procedure. Primary endpoint was cross-over to the other device or residual LAA patency at 45-day CCTA. Secondary endpoints were procedural complications, device-related thrombus, peripheral patency detected on 45-day TEE, and clinical outcomes.

Results
221 patients were randomly assigned to either the Amulet (111, 50.2%), or the Watchman 2.5 (the 25, or 22.7%, included before October 2019) or Watchman FLX (85, 77.3%). Of the patients in the Watchman group, 25 (22.7%) were treated with Watchman 2.5 and 85 (77.3%) with Watchman FLX. Primary outcome assessment was evaluated in 205 patients. The primary endpoint occurred in 71 (67.6%) patients with Amulet and 70 (70%) patients with Watchman. Only one justified cross-over occurred in a patient assigned to the Amulet group. In terms of clinical outcomes, no significant difference was observed between the two groups in the evaluation after 45 days. However, major procedure-related complications were found to be higher in the Amulet group (9%) compared to the Watchman group (2.7%) (p=0.047), and the most important reason for this difference was bleeding complications. The patency around the device detected on TEE on the 45th day was 27.5% in the Watchman group and 13.7% in the Amulet group. Device-related thrombus was observed in 1 patient in the Amulet group, 3 patients in the Watchman group in the CCTA evaluation, 2 patients in the Amulet group, and 5 patients in the Watchman group in the TEE evaluation.

Conclusions
As a result of this study, in patients with high bleeding risk undergoing clinically-indicated LAAC, Amulet, as compared with Watchman FLX was associated with similar residual LAA patency at 45-day CCTA, lower peri-device leak rates at 45-day on TEE, higher procedural complications, but similar clinical outcomes at 45 days.

Interpretation
The SWISS-APERO trial is the first randomized trial to compare two commonly used devices for the LAAC procedure. In the evaluation on the 45th day, while the Amulet was more advantageous in terms of the peri-device leak, it created serious problems in procedure-related complications. LAA patency and clinical outcomes at day 45 were similar in Amulet and Watchman devices. Although this is a superiority study for the Amulet, the study did not reach its goal in its current state. Long-term follow-up results will be more suitable for comparison of both devices.