Flow Diverter Coatings: A Comprehensive Review of the Mechanisms and Clinical Data Behind Coating Technology

Introduction: Flow diversion (FD) devices are a mainstay treatment for large wide-necked aneurysms. Despite excellent safety and efficacy, thromboembolic complications necessitate the use of dual antiplatelet therapy (DAPT). In order to circumvent this issue, the most recent generation of flow diverters are covalently coated with hydrophilic compounds to confer blood compatibility and limit clotting and thrombosis. Given the paucity of information on the mechanism of these surface modifications, we seek to fill this gap in the literature by consolidating information on the coating technology for three major FDs currently in clinical use – Pipeline Flex Shield Technology, FREDX, and p64-MW-HPC.

Methods: We collected information on device coatings, pre-clinical, and clinical studies using international databases (PUBMED, Embase, Medline, Google Scholar). We stratified our search criteria using the keywords “phosphorylcholine”, “PMEA”, “hydrophilic polymer coating”, “Pipeline Shield”, “FREDX”, “p64.”

Results: The hydrophilic surface modifications - phosphorylcholine, PMEA, and HPC - are effective in enhancing hemocompatibility and are proven in reducing thrombin deposition, inflammatory mediators, and allowing for neo-intimal hyperplasia in pre-clinical studies. Clinical studies for Pipeline Flex Shield Technology (PED-SHIELD) and p64-MW-HPC suggest excellent periprocedural and postprocedural outcomes, with minimal thromboembolic complications. The coating technologies each utilize water to create a barrier which can enhance navigability. In addition, each technology has a unique composition of water and must balance promoting hemocompatibility while minimizing interference with endothelial formation.

Conclusion : Each major coating has a unique chemical composition and mechanism that should be taken into consideration during device selection for treatment. Each coating technology is effective as demonstrated by pre-clinical studies, and PED-SHIELD and p64-MW-HPC have been found to be safe and effective in clinical studies, with further research needed to evaluate ruptured aneurysm FD treatment with single antiplatelet therapy (SAPT). FREDX needs further clinical studies to assess safety and efficacy.