Background: Stent-assisted coiling and extra-saccular flow diversion require dual anti-platelet therapy due to the thrombogenic properties of the implants. While both methods are widely accepted, thromboembolic complications and the detrimental effects of dual anti-platelet therapy remain a concern. Anti-thrombogenic surface coatings aim to solve both of these issues. Current developments are discussed within the framework of an actual clinical case.
Case description: A 33-year-old male patient lost consciousness while doing sport and was administered 500 mg acetylsalicylic acid on site. Computed tomography revealed a massive subarachnoid haemorrhage, and digital subtraction angiography showed an aneurysm of the right middle cerebral artery. Stent-assisted coiling using a neck bridging device with a hydrophilic coating (pCONUS_HPC) was considered as an appropriate approach. Another 500 mg acetylsalicylic acid IV was given. After the single anti-platelet therapy was seen to be effective, a pCONUS_HPC was implanted, and the aneurysm sac subsequently fully occluded using coils. No thrombus formation was encountered. During the following days, 2 × 500 mg acetylsalicylic acid IV daily were required to maintain single anti-platelet therapy, monitored by frequent response testing. Follow-up digital subtraction angiography after 13 days confirmed the occlusion of the aneurysm and the patency of the middle cerebral artery.
Conclusion: A variety of ways to reduce the thrombogenicity of neurovascular stents is discussed. Hydrophilic surface coatings are a valid concept to improve the haemocompatibility of neurovascular implants while avoiding the use of dual anti-platelet therapy. Phosphorylcholine and phenox hydrophilic polymer coating are currently the most promising candidates. This concept is supported by anecdotal experience. However, formalised registries and randomised trials are currently being established.
Keywords: Stent-assisted coiling; anti-thrombogenic coating; flow diversion; pHPC; phosphorylcholine.