Mechanical properties of currently available left atrial appendage occlusion devices: A bench-testing analysis

Endoluminal left atrial appendage occlusion is an emerging therapy to treat patients suffering from atrial fibrillation with contraindications against oral anticoagulation. Different occlusion devices have been introduced into the clinical setting while comparative studies between the devices are sparse. This in vitro study compares several endoluminal left atrial appendage occlusion systems regarding 2 mechanical properties: radial (RF) and tug force (TF). Seven different occluder systems of various sizes (24 in total) underwent testing throughout their recommended sizing range. RF was measured in a commercial RF tester. TF was assessed according to a recently published bench test. RF increased with compression of the devices: The LAmbre 2228 device exerted the highest RF (8.6 N) at maximum compression of 16 mm. The lowest RF of 0.1 N was exhibited by the 27 mm Occlutech occluder at minimal compression. The highest TFs were exerted by the WaveCrest devices at maximum compression with 4.6 and 3.6 N for the 22 mm and the 27 mm device, respectively. The lowest TFs were measured for the first-generation Occlutech devices, particularly for the 24 mm device with 1.1 N at maximum compression and 0.4 N at minimum compression. A strong positive correlation was found between the number of hooks per millimeter circumference of an occluder and its tug force (r = 0.87, P < 0.01). The analysis revealed device stability to be more dependent on anchoring structures than on RF. The wide range of mechanical properties makes comparison of current LAA occluders difficult and emphasizes the need for standardized preclinical testing to prompt clinical compatibility.