Thrombogenicity of stent graft materials as a potential contributing factor to limb graft occlusions

Limb graft occlusions (LGOs) remain a significant complication after endovascular aneurysm repair. Several clinical risk factors have been recognized, but these do not fully account for the consistently observed different LGO rates among major commercial stent graft systems. This paper investigates the thrombogenicity of stent graft materials as a potential factor for thrombus formation and therefore LGO.

The thrombogenicity of the graft materials from three commercially available stent grafts (Zenith Alpha, Endurant, and Excluder) was evaluated in vitro using whole blood from four human donors for 1 hour in a dynamic setup. Samples were examined qualitatively with scanning electron microscopy, and the blood was further evaluated quantitatively via enzyme-linked immunosorbent assays for key indicators of thrombogenesis: normalized platelet count in the blood as measure of platelets in the clot, thrombin-antithrombin complex (TAT), β-thromboglobulin (βTG), and the soluble complement membrane attack complex (sC5b9).

Qualitative analysis revealed voluminous blot clot formation on Zenith Alpha stent grafts, some blood components on Endurant fabric, and minimal thrombotic factors on Excluder fabric. Material from the Zenith Alpha exhibited the lowest normalized platelet count in the blood (P < .0001) and significantly higher TAT (P < .001) and βTG values compared with Excluder (P = .002), indicating quantitatively the highest thrombogenicity among the evaluated stent graft materials. The Endurant fabric was significantly less thrombogenic compared with Zenith Alpha based on normalized platelet count (P < .001) and TAT values (P < .001). The Excluder graft material had the highest normalized platelet count (P < .0001) and lowest values of TAT (P < .0001) and βTG (P < .018), indicating that it is significantly less thrombogenic compared with the other two fabrics. No clear trend was found for sC5b9 between the stent graft materials.

The materials used in three commercial stent graft systems have significantly different in vitro thrombogenic properties and thrombus formation on the fabrics.

The found variations of material thrombogenicity between the Zenith Alpha, Endurant, and Excluder stent grafts appear to align with their reported clinical limb graft occlusion rates of these devices. By considering material thrombogenicity and thus thrombus formation, clinicians gain a deeper understanding of device-specific risks that may guide stent graft selection and postprocedural management. In general, these findings exemplify the potential relationship between implantable material properties and clinical complications, which remains insufficiently explored.