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 $20\times 30\text{mm}$ to $15\times 33\text{mm}$ and the large from $30\times 35\text{mm}$ to $20\times 40\text{mm}$ . 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.