Abstract 221: Challenging the Norm: Large Stent Retrievers Show No Disadvantage in Medium Vessel Occlusions

Background Mechanical thrombectomy has become widely used in order to treat patients with ischemic stroke. While studies have examined the effect of stent retriever size in various cerebral vessels, the efficacy of differently sized stent retrievers for mechanical thrombectomy in M2 segment middle cerebral artery (MCA) occlusions is as of yet unknown. Understanding the efficacy of differently sized stent retrievers could lead to better outcomes for affected patients, therefore this retrospective study examines 3mm, 4mm, and 6mm stent retrievers in order to determine how size affects patient outcomes. Methods Data collected from M2 MCA strokes in a comprehensive stroke center was retrospectively analyzed and multivariable analysis performed. Patient outcomes were quantified using NIHSS 24 hours post procedure and modified Rankin score (mRS) at discharge and after 90 days. Successful outcomes were defined as an NIHSS score of less than 10 and an mRS score less than 3. First pass success rate and final TICI scores of 3 were used to quantify successful recanalization while noting the incidence of complications such as symptomatic intracranial hemorrhage. Time from puncture to recanalization was also collected to give an idea of the difficulty of the procedure. Variables were compared using Chi Square, ANOVA and Kruskal Wallis tests, with subgroup analysis performed to further investigate between group differences as needed. Results A total of 139 patients were included who underwent thrombectomy with stent retrievers sized 3mm (n=23), 4mm, (n=56), and 6mm (n=60). No significant between group difference was noted in baseline demographics, clinical characteristics, 24h NIHSS (p=0.83), 24h NIHSS <10 (0.2), mRS at discharge (p=0.14), mRS at 90 days (p=0.07), time from puncture to recanalization (p=0.12), first pass success rate (p=0.98) and rate of final TICI 3 (p=0.21). All three sizes had similar rates of complication, with no significant difference in rates of death (p=0.46) or symptomatic intracranial hemorrhage (p=0.32). These findings were further supported by a multivariable regression model adjusting for baseline NIHSS and other relevant factors. Discussion This retrospective study failed to show a significant difference between differently sized stent retrievers in treating isolated M2 occlusion. This study was limited by its sample size andpotential unmeasured confounders such as variation in M2 occlusion severity. Further clinical trials are needed to determine whether the location or extent of the occlusion are important factors that might affect the efficacy of differently sized stent retrievers.