Background: Underlying intracranial stenosis is the most common cause of failed mechanical thrombectomy in acute ischemic stroke patients with large vessel occlusion. Adjunct emergent stenting is sometimes performed to improve or maintain reperfusion, despite limited data regarding its safety or efficacy. Methods: We conducted a prospective multicenter observational international cohort study. Patients were enrolled between January 2022 and December 2023 at 25 thrombectomy capable centers in North America, Europe, and Asia. Consecutive patients treated with mechanical thrombectomy were included if they were identified as having underlying intracranial stenosis, defined as 50-99% residual stenosis of the target vessel or intra-procedural re-occlusion. The primary outcome was functional independence, defined as modified Rankin Scale of 0-2 at 90 days. After applying inverse probability of treatment weighting (IPTW) based on propensity scores, we compared outcomes among patients who underwent adjunct emergent intracranial stenting (stenting) versus those who received mechanical thrombectomy alone. Results: A total of 417 patients were included; 218 patients treated with mechanical thrombectomy alone (168 anterior circulation) and 199 with mechanical thrombectomy plus stenting (144 anterior circulation). Patients in the stenting group were less likely to be non-Hispanic White (51.8% vs 62.4%, p=0.03), and less likely to have diabetes (33.2% vs 43.1%, p=0.037) or hyperlipidemia (43.2% vs 56%, p= 0.009). In addition, there was a lower rate of IV thrombolysis use in the stenting group (18.6% vs 27.5%, p=0.03). There was a higher rate of successful reperfusion (modified Treatment In Cerebral Infarction score ≥ 2B) in the stenting versus mechanical thrombectomy alone group (90.9% vs 77.9%, p&lt;0.001) and a higher rate of a 24-hour infarct volume of &lt;30 mL (n=260, 67.9% vs 50.3%, p=0.005). The overall complication rate was higher in the stenting group (12.6% vs 5%, p=0.006), but there was not a significant difference in the rate of symptomatic hemorrhage (9% vs 5.5%, p=0.162). Functional independence at 90 days was significantly higher in the stenting group (42.2% vs. 28.4%, adjusted odds ratio 2.67; 95% CI, 1.66-4.32). Conclusions: In patients with underlying stenosis who achieved reperfusion with mechanical thrombectomy, adjunct emergent stenting was associated with better functional outcome without a significantly increased risk of symptomatic hemorrhage. Registration: https://clinicaltrials.gov/study/NCT05403593

Outcomes of Adjunct Emergent Stenting Versus Mechanical Thrombectomy Alone: The RESCUE-ICAS Registry