Abstract Body (Do not enter title and authors here): Introduction: Left atrial appendage occlusion (LAAO) is an effective method of stroke prevention in patients with atrial fibrillation (AF). However, peri-device leakage (PDL) and device related thrombus (DRT) are common limitations of LAAO. Notably, PDL is associated with an increased risk of thromboembolic events. In order to minimize DRT, the Watchman FLX Pro is coated with PVDF-HFP. We aim to minimize both DRT and PDL with our novel zonal coating application system (ZCAS). ZCAS integrates a two-part thromboresistant and endothelialization promoting coating onto LAAO devices (Figure 1). In order to determine the optimal coating for the endothelialization promoting zone of ZCAS, we validated coating candidates in an in vitro model of LAAO device endothelialization (Figure 2).

Hypothesis: We hypothesized that polyethylene terephthalate (PET) mesh coated with collagen type IV, fibronectin + VEGF, or poly-L-lysine would improve endothelial cell viability and proliferation.

Methods: Human umbilical vein endothelial cells (HUVEC) were cultured in DMEM/F12 supplemented with ATCC’s Endothelial Cell Growth Kit and antibiotics. For the cell viability and proliferation assay, HUVEC cells were cultured in DMEM/F12 supplemented with 2% FBS, 10 mM L-glutamine, and antibiotics. A 96 well plate with PET inserts was coated with three coating candidates. Each coating was applied in three concentrations ([1x], [10x], and [100x]) with triplicates for each concentration. The coatings included collagen type IV ([1x]: 1 ug/cm2), fibronectin ([1x]: 1 ug/cm2) + VEGF ([1x]: 10 ng/cm2), and poly-L-lysine ([1x]: 4 ug/cm2). An MTS assay was performed at 48 hours after plating to assess cell viability and proliferation.

Results: MTS absorbance relative to the uncoated control (MTS absorbance coated well/MTS absorbance uncoated well) for collagen type IV at [1x], [10x], and [100x] was 0.81, 1.29, and 0.84 respectively (Table 1). Fibronectin + VEGF at [1x], [10x], and [100x] was 1.31, 1.62, and 0.96. Finally, poly-L-lysine at [1x], [10x], and [100x] was 0.69, 0.90, and 0.91 respectively.

Conclusion(s): Among the coating candidates, fibronectin (1 ug/cm2) + VEGF (100 ng/cm2) had the greatest increase in cell viability and proliferation compared to the uncoated PET control. The significance of this finding lies in the potential for ZCAS to improve the endothelial seal between the LAAO device and LAA orifice, which may significantly reduce PDL post-implantation.