Stent Thrombogenicity is Modulated by Design: Wire Crossings in Braided Stents are Focal Thrombogenic Niches

Stent thrombosis remains a critical and fatal complication of angioplasty with stenting, particularly in tandem lesion patients, where the incidence can exceed 20%. A better understanding of the thrombogenicity of clinically used stents could reduce the occurrence of stent thrombosis. We have developed a macrofluidic model mimicking the geometry of the human carotid artery, which is perfectly suited to evaluate the intrinsic thrombogenicity of carotid stents. Real-time video microscopy and scanning electron microscopy were combined to assess the thrombogenicity of three clinically used carotid stents: the laser-cut Protégé RX stent, the braided Casper stent, and Wallstent. The Casper and the Wallstent led to higher rates of platelet adhesion and thrombus formation than the Protégé RX. The thrombi were essentially localized at the intersections of the metal wires in the braided stents, whereas in the laser-cut stent, only more evenly distributed platelet adhesion was observed. Hot spots of thrombosis were identified at the crossings of the stent struts, especially around the external wires of these crossings, which are in contact with the vessel wall. Thrombus formation was effectively prevented in the presence of aspirin or the αIIbβ3 blocker abciximab. Computational fluid dynamics indicated that the wire crossings of braided stents generate a prothrombotic shear environment, with flow recirculation and stagnation regions leading to thrombus formation, as demonstrated by a macroscale in silico simulation. Design plays a major role in thrombus formation on stent wires, with braided stents being more thrombogenic than laser-cut stents.