Complete vs Near-Complete Reperfusion After Endovascular Therapy for Anterior-Circulation Large-Core Stroke: Propensity-Matched 90-Day Outcomes and Collateral-Modified Time Effects

Background: In endovascular therapy (EVT)-treated anterior-circulation large-core stroke, the incremental value of complete reperfusion modified thrombolysis in cerebral infarction (mTICI 3) over near-complete reperfusion (mTICI 2b) is unclear, and collateral physiology may modify time-related tissue injury and recovery. Methods: This retrospective cohort included adults with anterior-circulation large-vessel occlusion, Alberta Stroke Program Early CT Score (ASPECTS) of 3-5, successful reperfusion (mTICI: ≥2b), pretreatment diffusion-weighted imaging (DWI) core volumetry, and 90-day outcome data (n = 106). A 1:1 propensity score match compared final mTICI 2b versus final mTICI 3 (matched n = 84; 42 per group). Prespecified interaction models tested with American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) collateral grade as an effect modifier of onset-to-reperfusion time. Results: The mTICI 2b group required more thrombectomy passes (median: 2 vs 1; p < 0.001). Functional independence (modified Rankin Scale (mRS): 0 to 2) was similar for mTICI 2b versus mTICI 3 (10/42 (23.8%) vs 11/42 (26.2%); adjusted odds ratio (OR): 1.21; p = 0.66). Symptomatic intracranial hemorrhage (sICH) was higher with mTICI 2b (6/42 (14.3%) vs 2/42 (4.8%); p = 0.04), while 90-day mortality was similar (15/42 (35.7%) vs 13/42 (31.0%); p = 0.75). A longer onset-to-reperfusion time was associated with a larger DWI core (+5.8 cc per hour; p = 0.01) and lower odds of functional independence (OR: 0.78 per hour; p = 0.04). Higher collateral grade was associated with smaller core (-8.4 cc per grade; p = 0.02) and higher odds of independence (OR: 2.5 per grade; p = 0.01). Time × collateral interactions were significant for core (β -2.1; p = 0.03) and independence (OR: 1.19; p = 0.04). Conclusions: In large-core endovascular therapy (EVT) with successful reperfusion, mTICI 3 did not improve 90-day functional outcomes versus mTICI 2b but was associated with fewer symptomatic hemorrhages, supporting physiology-informed urgency and counselling in this high-risk population. Procedural escalation beyond mTICI 2b should be individualized in large cores overall.