Collateral status and outcomes in ICAS-LVO: insights from the RESCUE-ICAS registry

Background Collateral circulation influences outcomes in large-vessel occlusion (LVO) stroke, yet its modifying effect on endovascular therapy for intracranial atherosclerosis-related LVO (ICAS-LVO) remains uncertain. This study evaluated whether collateral status alters the association between stent-assisted thrombectomy and outcomes in anterior-circulation ICAS-LVO. Methods An analysis was performed on 271 anterior-circulation ICAS-LVO patients from the RESCUE-ICAS registry. Collateral status was graded using the Tan collateral score (0–1 = poor, 2–3 = good). Patients were treated with mechanical thrombectomy (MT) alone or MT with adjunctive stenting. The primary outcome was functional independence (modified Rankin Scale [mRS] = 0–2) at 90 days. Secondary outcomes included successful reperfusion (mTICI≥2b), symptomatic intracranial hemorrhage (sICH), and mortality. Results Among 271 patients, 172 (63.5% ) had good, and 99 (36.5%) had poor collaterals. In adjusted interaction models, stenting improved 90-day functional independence (aOR 3.22, p = 0.030) without significant stent–collateral interaction ( p = 0.876). No significant interactions were observed for mortality ( p = 0.847) or sICH ( p = 0.909). A significant adjusted interaction was present for final recanalization (interaction OR 8.35, p = 0.044). Conclusions In anterior-circulation ICAS-LVO, adjunctive stenting was associated with improved functional outcomes across collateral strata, with collateral status showing some modification of the stent effect on angiographic success.