Approach to Left Atrial Appendage Closure Takes a Turn

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EP LAB DIGEST. 2024;24(1):6.

Dear Readers,

There are only 2 commercially-available left atrial appendage closure (LAAC) devices that are approved by the US Food and Drug Administration for the prevention of stroke in patients with atrial fibrillation (AF): the Watchman (Boston Scientific), a strawberry-shaped, single plug type device, and the Amplatzer Amulet (Abbott), a two-part device with a plug and disk. Both occluders took years of research and evidence development before coming to market. The Watchman device took 3 FDA panels before getting approval. Both are safe and effective in closing the LAA. The LARIAT suture snare was approved for soft tissue closure, but does not have FDA labeling specific for LAAC to prevent stroke. The approach for this suture snare system requires both pericardial and transseptal endocardial LAA access to place magnet-tipped guidewires as a rail to externally ligate the LAAC using a minimally invasive approach.

The approved LAAC plug devices have evolved significantly over the years in ways that have greatly increased the rate of successful occlusion, minimized the risk of embolization, and reduced the incidence of procedural complications. The new Watchman FLX Pro has a novel fluoropolymer coating on the fabric covering the face of the device and has the potential to promote endothelialization and reduce device-related thrombi (DRT).¹ This may ultimately allow for single antiplatelet therapy after implantation. However, the current devices still have room for improvement. Concerns about even small peri-device leaks remain, and there continue to be technical challenges when trying to occlude some appendages that are shaped like a chicken wing, have large proximal pectinate muscles, or are very large or small.

A new technique for LAAC has emerged: the Laminar device (Laminar, Inc). The Laminar device includes a transseptal delivery system with a deployable cage on the end of the cable. The cage is spherical with splines that can be advanced and anchored into the LAA and rotated to twist the LAA closed from the inside. An analogy is twisting the end of a plastic bag on a loaf of bread. Then, a star-shaped lock is placed up against the endocardial tissue with tines that lock the cage in position. When the device is released, the LAA is completely excluded with very little device exposed to the systemic circulation. It is not clear if this technique results in electrical isolation of the LAA as occurs with the LARIAT system, but a potential advantage of this approach compared to an occluder device is that it minimizes the risk of peri-device leak and DRT. Encouraging preclinical animal data and first-in-human data with the Laminar device were recently published.² The Laminar device was successfully implanted in 10 dogs with no leak or DRT at 45 and 150 days. Histology showed fully closed LAAs covered with neo-endocardium. The device was also successfully implanted in 15 patients with complete closure and no DRT at 45 days by TEE and computed tomography. There were no complications after 12 months of follow-up.

On November 30th, 2023, the Laminar LAAC technology was acquired by Johnson & Johnson MedTech, as part of Biosense Webster.³ Although there were only data related to the use of this device in a small number of patients, the reported purchase price for Laminar was a whopping $400 million with additional potential clinical and regulatory milestone payments in 2024 and beyond. This investment is an indication that there is still room for improvement with LAAC technologies and that there is a huge market. 

References

1. Saliba W, Kawai K, Sato Y, et al. Enhanced thromboresistance and endothelialization of a novel fluoropolymer-coated left atrial appendage closure device. JACC Clin Electrophysiol. 2023;9(8 Pt 2):1555-1567. doi:10.1016/j.jacep.2023.04.013 1567.https://doi.org/10.1016/j.jacep.2023.04.013.

2. Wong GX, Kar S, Smith TW, et al. Transcatheter left atrial appendage exclusion: preclinical and early clinical results with the Laminar device. JACC Cardiovasc Interv. 2023;16(11):1347-1357. doi:10.1016/j.jcin.2023.04.028

3. Johnson & Johnson MedTech acquires Laminar, Inc. News Release. Johnson & Johnson; November 30, 2023. Accessed December 13, 2023. https://www.jnj.com/johnson-johnson-medtech-acquires-laminar-inc

Disclosures: Dr Knight has served as a paid consultant to Medtronic and was an investigator in the PULSED AF trial. In addition, he has served as a consultant, speaker, investigator, and/or has received EP fellowship grant support from Abbott, AltaThera, AtriCure, Baylis Medical, Biosense Webster, Biotronik, Boston Scientific, CVRx, Philips, and Sanofi; he has no equity or ownership in any of these companies.