Preclinical Assessment of a Novel Conformable Foam-Based Left Atrial Appendage Closure Device

Abstract

Background. Left atrial appendage (LAA) occlusion has been established as an alternative to systemic anticoagulation for stroke prevention in patients with atrial fibrillation; however, limitations of current devices have slowed adoption. We present preclinical evaluations of a novel device, the Conformal Left Atrial Appendage Seal (CLAAS). Methods. An in vitro assessment of conformability was conducted to evaluate the two CLAAS devices (regular 27 mm and large 35 mm) and a Watchman 2.5 (27 mm). Devices were placed within silicone tubes and compressed in a vise submerged in a water bath at 37°C. Changes in device diameter and visual seal were noted. Acute ( n = 1 ) and chronic 60-day ( n = 6 ) canine studies with gross and histologic assessment were performed. Results. Conformability bench tests demonstrated that the regular CLAAS implant was able to seal oval orifices from 20 × 30 mm to 15 × 33 mm and the large from 30 × 35 mm to 20 × 40 mm . As the CLAAS implant was compressed in the minor diameter, it increased in the major diameter, thereby filling the oval space, whereas the Watchman 2.5 showed gaps and maintained its round configuration when compressed in one direction. Seven devices were successfully implanted in the canine model with complete seal without thrombus. Histologic examination showed complete neointima covering with minimal inflammation at 60 days. Conclusions. Preclinical testing demonstrated the conformability of the CLAAS implant and its ability to seal the LAA. Clinical studies are ongoing to characterize the utility of the CLAAS implant in the treatment of patients with atrial fibrillation.

Percutaneous Left Atrial Appendage Occlusion Therapy: Past, Present, and Future

“…The implant is attached to the delivery catheter with a flexible suture tether, which is used for recapture and redeployment before final release (Figure 8C, 8D). Preclinical assessment performed in seven dogs has demonstrated the conformability of the CLAAS implant and its ability to seal the LAA [103]. Histologic examination has indicated complete neointima covering with minimal inflammation at 60 days.…”

Transcatheter Left Atrial Appendage Closure: Devices Available, Pitfalls, Advantages, and Future Directions

“…In a preclinical study of device implantation in seven healthy male canines in sinus rhythm, at 60 days, histologic examination showed complete neointima covering with minimal inflammation. 9 In a report of 15 patients using intracardiac echocardiography-guided deployment of this device, the success rate was 100%, and there were no procedure/device-related complications. At 1 year, there was no significant peri-device leak (>5 mm), and DRT was detected in one patient at 6 months.…”

Left Atrial Appendage Occlusion and Post-procedural Antithrombotic Management

“…Other devices, such as the Conformal and Laminar technologies, might further challenge the need for post-procedural treatment. With a very limited nitinol frame and a highly conformable and porous foam cup, the Conform Left Atrial Appendage Seal (CLAAS) design is meant to promote LAA sealing by improved adaption to the LA wall and increased tissue ingrowth [99,100]. In a preclinical canine study (n = 7), CLAAS achieved complete seal, no thrombus, and full neointimal coverage in all cases at 60 days [99].…”

“…With a very limited nitinol frame and a highly conformable and porous foam cup, the Conform Left Atrial Appendage Seal (CLAAS) design is meant to promote LAA sealing by improved adaption to the LA wall and increased tissue ingrowth [99,100]. In a preclinical canine study (n = 7), CLAAS achieved complete seal, no thrombus, and full neointimal coverage in all cases at 60 days [99]. Nevertheless, the limited published human data still include DAPT as discharge therapy [100,101].…”