Impact of collateral status on functional outcomes in acute cardioembolic stroke after successful endovascular thrombectomy

Background: Collateral circulation sustains the ischemic penumbra during acute large vessel occlusion (LVO). However, its prognostic significance in cardioembolic stroke (CS) patients following successful endovascular thrombectomy (EVT) remains unclear. We investigated whether collateral status influences functional outcomes in acute CS patients achieving successful recanalization [modified Thrombolysis in Cerebral Infarction (mTICI) grade ≥2b]. Methods: We retrospectively analyzed consecutive CS patients achieving successful recanalization with EVT. Collateral status was assessed using the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) grading system on digital subtraction angiography (DSA). The primary outcome was functional independence [modified Rankin Scale (mRS) 0-2] at 3 months. Secondary outcomes included excellent outcome (mRS 0-1) at 3 months, in-hospital and 3-month mortality, and PH (parenchymal hematoma type 1c or 2) within 72 h. Multivariable logistic regression and subgroup analyses were performed to identify independent associations. Results: for interaction = 0.007). Conclusion: In CS patients achieving successful recanalization, good collateral status is independently associated with improved functional independence and excellent outcome, reduced PH rates within 72 h, and lower in-hospital mortality and 3-month mortality. Collateral assessment may enhance prognostic stratification, particularly in patients with lower baseline ASPECTS.