Abstract WP142: Investigating the Association of Intracranial Stenosis With Low Wall Shear Stress

Abstract

Background: Intracranial atherosclerotic disease (ICAD) is associated with high recurrence rates of stroke despite aggressive medical management. Low wall shear stress (WSS) alters endothelial function and changes in WSS within the post-stenotic region of ICAD lesions is a potential driver of stroke recurrence. Methods: Using the SAMMPRIS imaging dataset, we identified medically managed patients with symptomatic middle cerebral artery (MCA) stenosis measured by CTA. WSS was calculated by creating a 3D volumetric mesh from CTA source imaging. Pulsatile flow profile reference standard boundary conditions were applied at pressure outlets to simulate normal hemodynamics. Arterial segments extending from the stenosis to the MCA bifurcation were captured and quantified. Contralateral arterial segments were matched by length and area. The ratio of area with low WSS (<4 dyne/cm 2 ) on both sides was then calculated. Differences in the mean arterial area with low WSS and ratio of area with low WSS were compared using paired Student’s t-test with data presented as mean ± SD. Results: Of 451 cases in SAMMPRIS, the medical management arm had 105 MCA cases of which 47 cases had CTA available and 33 cases were able to be analyzed by computational flow dynamics. Symptomatic ICAD lesions demonstrated significant differences in post stenosis area with low WSS (24.7±43.4 mm 2 vs 2.8±3.4 mm 2 p=0.003) and differences in the low WSS ratio (0.25±0.26 vs0.04±0.05 p<0.001). There was no statistically significant difference in the length and area of the arterial segment post stenosis to the bifurcation and the control length on the contralateral side (11.6±7.4 mm vs 10.6±6.1 mm p=0.566; 80.7±55.0 mm 2 vs 95.4±58.3 mm 2 p=0.298). Conclusion: Area with low WSS after ICAD stenoses is increased in the SAMMPRIS imaging dataset and may be a marker of symptomatic ICAD. Further studies are needed to evaluate the association of post stenotic WSS with symptomatic recurrent stroke.