Comparative safety of stent retriever designs for intracranial atherosclerotic disease related large vessel occlusion using agarose models

Establishing an optimal first-line approach for suspected intracranial atherosclerotic disease (ICAD)-related acute large vessel occlusion (LVO) remains challenging. We developed an ICAD model using an agarose phantom to investigate the specific features of the stent retriever (SR) design for ICAD-LVO for safety use. An ICAD model that reproduced the mechanical features of plaque was developed to quantify the pull-out resistance and intraluminal injury caused by SRs. The impacts of vessel factors (ICAD existence and plaque stiffness) and SR design (non-segmented, segmented, and manually-controllable-diameter) were evaluated using this model. In the 6% agarose (as soft plaque) ICAD model, SR caused significantly higher pull-out resistance and severe intraluminal injury compared with the non-ICAD model or the 10% agarose (as hard plaque) ICAD model with almost all SRs. In the 6% ICAD model, non-segmented, rather than segmented, SRs seemed to reduce pull-out resistance and intraluminal injury. Longer SRs strengthened the benefit of non-segmented design. SRs with manually controllable diameter, when fully relaxed before retrieval, seemed to provide the safest option among all SR designs, while those with usual handling such as slight relaxation before retrieval seemed to be the most harmful due to specific deformation. Using SRs for ICAD-LVO may increase pull-out resistance and intraluminal injury, particularly in ICAD involving soft plaques. SR use safety for ICAD seems to depend largely on SR design and handling procedures of manually controllable diameter SRs.