The Healing Response of LAMax LAACTM Left Atrial Appendage Occluder in a Canine Model: The Potential Influence of the Implantation Technique on the Healing Response

Abstract Background: Device-associated thrombus are potential causes for thromboembolic events post left atrial appendage closure (LAAC), and correlated with the complete endothelialization of the device surface. Our aim was to evaluate the endothelialization of LAMax LAACTM occluder surface and analyze the potential influence of the implantation technique on the healing response.Methods: A total of 29 healthy dogs (28.0±3.7 kg) were implanted with the devices successfully after ensuring COVER signs was met (Concavity of the disc, Oversizing by 20-50%, Verifying position, Ensuring stability, Residual flow <5 mm by transesophageal echocardiographic (TEE) examination), and sacrificed at <24 hours, 1-, 2-, 3-, and 6-months. Gross examinations were conducted to evaluate healing response.Results: The mean diameters of LAA orifice measured by angiography and TEE were 19.0±2.9 mm and 16.1±2.0 mm (P<0.05), respectively. TEE found that the discs in 18 dogs (62.1%) were completely pulled into the LAA with concavity and in 11 dogs incompletely pulled into the LAA with suboptimally concavity, while 5 of them had residual flow. Gross examinations showed that the complete endothelialization on the device surface with concaved disc was found at 1-month after LAAC. Microscopic examinations confirmed complete healing on the device with optimal closure effect. Conclusions: The good healing response and the optimal closure effect were observed using the LAMax device in a canine model by following the COVER implantation technique.