The Watchman FLX – a new device for left atrial appendage occlusion – design, potential benefits and first clinical experience

Introduction

Although convincing data showed that left atrial appendage (LAA) occlusion could be used as an alternative to oral anticoagulants, LAA occlusion has emerged as a common procedure for stroke prevention in patients with atrial fibrillation and absolute or relative contraindications for oral anticoagulation in many European centers, based on current recommendations of the European Society of Cardiology. The efficacy and safety of the current generation Watchman LAA Closure System was established in two large randomized clinical trials (PROTECT AF, PREVAIL [1, 2]) and several prospective registries (CAP, ASAP, EWOLUTION [3–5]).

Device description

The Watchman FLX (Boston Scientific) is the newest generation of LAA closure devices, which has been available since November 2015 in Europe, after CE mark approval. It has several new features compared to the previous generation of Watchman. The Watchman FLX device is available in 5 sizes (20, 24, 27, 31 and 35 mm) for ostia measuring from 15 mm to 32 mm in width and therefore can treat both smaller and larger LAA ostia compared to the previous generation of Watchman. A reduced device length enables implantation even in more shallow LAAs.
The Watchman FLX device is a self-expanding nitinol frame structure with fixation anchors and a permeable polyester (PET) fabric cover facing the LAA. The proximal face is flat with a reduced, minimal area of metal screw facing the left atrium to encourage endothelialisation and reduce post-implant thrombus formation. The nitinol 18-strut frame (compared to the 10-strut frame in the previous version) provides 80% more contact points at the LAA ostium and radially expands to maintain a proper position in the LAA. Atraumatic closed distal end has a fluoroscopic marker which enhances procedural visibility. Twelve “J” shaped fixation anchors in two rows create a proximal and distal line to aid in device stabilization in different anatomies of the LAA (10 in one row in the previous version). Intra-LAA placement avoids contact with the left atrial wall to reduce the risk of device erosion and minimizes interference with the left upper pulmonary vein and mitral valve. A greater range of compression is allowed, ranging from 10% to 27%. Based on the animal data and early operators’ experience from other centers (unpublished data) the Watchman FLX device has performed best when not overcompressed. Excessive oversizing is not recommended since the...


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