Introduction Subarachnoidal hyperdensities (SH) on flat detector CT (FDCT) after mechanical thrombectomy (MT) are associated with neurological incline and less favorable clinical outcome; SH are more common in distal occlusions and after multiple device passes. With technical advancements, neurointerventionalists are aiming to treat further distal occlusions, with several randomized trials underway

Aim of Study We aimed to further identify the prevalence and clinical significance of SH on FDCT following MT, especially in patients with dominant, co- and non-dominant caliber M2 occlusions

Methods 640 patients from two comprehensive stroke were analyzed for the presence of SH on FDCT and then classified according to a visual grading scale. 351 patients were included. The primary outcome was mRS at 90 days and was analyzed with the Wilcoxon-Mann-Whitney rank-sum test. To identify predictors regression analysis, Kruskal-wallis analysis and X² test were performed

Results Prevalence of SH on FDCT was 144/351 (40.9%) with patients experiencing a significant more unfavorable outcome (p=0.014). Distal occlusions and a higher number of device passes were significantly associated with SH (P<0.001) and (P=0.006), respectively.

SH was significantly more frequent (p=0.014) in co- and non-dominant M2 occlusions 41/63 (65.07%) compared to dominant M2 occlusions 35/79 (44.3%), with a significant effect p <0.001 OR= 4.18 (95%CI 2.28-7.69). Higher number of device passes >3 and < 6 had a significant effect on the occurrence of SH P< 0.001 OR= 3.42 (95%CI 1.76-6.67).

Conclusion SH is associated with worse functional outcome, with co- and non-dominant M2 occlusions and higher numbers of device passes >3.

Disclosure of Interest no.