Predictors of Futile Recanalization after Mechanical Thrombectomy for Embolism-Related Large Vessel Occlusion in the Anterior Circulation.

Objective: Futile recanalization (FR)-a poor functional outcome despite successful reperfusion after mechanical thrombectomy (MT)-remains a significant issue in acute ischemic stroke owing to large vessel occlusion. This study aimed to identify predictors of FR, focusing on CT perfusion (CTP) parameters using our institutional retrospective data. Methods: Patients who underwent MT at our institution between April 2015 and February 2023 were retrospectively reviewed. FR was defined as a 90-day modified Rankin Scale (mRS) score of 3-6 despite successful reperfusion (modified thrombolysis in cerebral infarction ≥2b). Patients with internal carotid artery (ICA) or M1 segment of the middle cerebral artery occlusion, pre-stroke mRS 0-2, stroke etiology classified as cardioembolic or embolic stroke of undetermined source, and available CTP were included. The ischemic core was defined as cerebral blood volume (CBV) <1.0 mL/100 g on CTP, and the Alberta Stroke Program Early CT Score (ASPECTS) was also evaluated. Clinical, imaging, and procedural variables were compared between the FR group and those with a favorable outcome (mRS 0-2) after successful reperfusion. Multivariable logistic regression was performed, including imaging markers and variables with p <0.1 in univariate analyses as covariates. Receiver-operating characteristic (ROC) analyses determined thresholds for ASPECTS and CBV-defined core volume, followed by sensitivity analyses. Results: A total of 531 patients underwent MT during the study period, of whom 136 met the inclusion criteria (mean age 78 ± 11 years, 70 women, 46 ICA occlusions, median ASPECTS 9; interquartile range, 7-10). FR was observed in 69 patients (50.8%). Compared with the favorable outcome group, the FR group had significantly older age, higher baseline NIHSS scores, higher prevalence of diabetes mellitus, lower ASPECTS, larger CBV-defined core volumes, and a greater total number of device passes. Multivariable logistic regression identified older age, higher NIHSS, diabetes mellitus, and a greater total number of device passes as consistently independent predictors of FR. ROC analysis identified CBV-defined core volume ≥28.5 mL as an independent predictor of FR (area under the curve [AUC] 0.62, p = 0.013; adjusted odds ratio [aOR] 3.09, 95% confidence interval [CI] 1.23-8.28; p = 0.02); this association remained significant at ≥30 mL (aOR 2.82, 95% CI 1.14-7.33; p = 0.02) but not at ≥40 mL. ASPECTS ≤8 was also associated with FR (AUC 0.64, p = 0.002; aOR 2.92, 95% CI 1.20-7.44; p = 0.02). Conclusion: Older age, baseline stroke severity, diabetes mellitus, and multiple device passes were major predictors of FR. Among imaging markers, a CBV-defined core volume of approximately 30 mL emerged as a clinically relevant threshold associated with increased FR risk. These findings suggest that integrating clinical, procedural, and imaging factors may help optimize patient selection, although validation in larger, multicenter studies is warranted.