Comparison of the Thrombogenicity of a Bare and Antithrombogenic Coated Flow Diverter in an In Vitro Flow Model

BACKGROUND: Dual antiplatelet therapy is a pre-requisite for flow diverter (FD) implantation. The purpose of this study was to assess the thrombogenicity of the p48 FD, coated with the newly developed phenox Hydrophilic Polymer Coating (p48_HPC, phenox GmbH, Germany) in comparison with uncoated p48 FDs in an in vitro flow model (Chandler Loop). METHODS: p48 and p48_HPC FDs were implanted into silicon tubes filled with whole human blood and incubated at 37 °C under pulsating flow. After 120 min, platelet count was determined in the blood. Platelet activation markers (PAR1) and formation of microparticles were analyzed in a flow cytometer. Fluorescence microscopy of CD42a positive cells and scanning electron microscopy was used to detect adherent platelets on the wire surface. RESULTS: Platelets in contact with the uncoated p48 FDs are significantly more activated than those incubated with p48_HPC (73 ± 9% vs. 65 ± 6%, p < 0.05) and release more microparticles (1.8 ± 0.5 vs. 1.4 ± 0.4, p < 0.05). The platelet count after 120-min circulation in the Chandler Loop was significantly lower for the uncoated p48 compared to the p48_HPC indicating significantly greater adherence of the platelets to the p48 (71 ± 8% vs. 87 ± 5%, p < 0.05). SEM and fluorescent antibody imaging revealed minimal platelet adherence to the surface of the p48_HPC compared to the uncoated p48. CONCLUSION: The pHPC coating significantly reduces thrombogenicity of the p48 FD. This may help to reduce the risk of thromboembolic complications when using these devices. A reduction in antiplatelet therapy may be possible.