Final Infarct Volume as a Surrogate End Point in Anterior Circulation ICAS-LVO Stroke: Post Hoc Secondary Analysis of RESCUE-ICAS.

BACKGROUND: Final infarct volume (FIV) on 24-hour magnetic resonance imaging is a well-established imaging biomarker linked to functional recovery after ischemic stroke, yet its prognostic value in intracranial atherosclerosis-related large vessel occlusion remains poorly explored. The impact of adjunct intracranial stenting on both infarct size and progression also remains unclear in this population. This study aimed to examine the association between FIV and clinical outcome, evaluate the effect of adjunct stenting on FIV and infarct progression, and assess the relationship between infarct progression and functional independence.

METHODS: We conducted a post hoc secondary analysis of the RESCUE-ICAS registry (Registry of Emergent Large Vessel Occlusion due to Intracranial Stenosis); only patients with anterior circulation large vessel occlusion with magnetic resonance imaging after thrombectomy were included. FIV was measured on diffusion-weighted magnetic resonance imaging performed 24 to 36 hours postthrombectomy. Infarct progression was defined as the difference between baseline computed tomography perfusion infarct volume (cerebral blood flow <30%) on presentation and 24- to 36-hour FIV. The primary outcome was 90-day functional independence (modified Rankin Scale score 0-2). Additional analyses evaluated the association between adjunct intracranial stenting and FIV, and the association between infarct progression and 90-day functional outcome. Associations were analyzed using multivariable logistic regression and inverse probability of treatment weighting.

RESULTS: Of the 417 patients included in RESCUE-ICAS, 203 had anterior circulation intracranial atherosclerosis-related large vessel occlusion and underwent magnetic resonance imaging 24 to 36 hours postthrombectomy. Among these, 80 patients (39%) received adjunct stenting. FIV was independently associated with 90-day functional independence (adjusted odds ratio per 10 mL increase, 0.8 [95% CI, 0.68-0.94]; P=0.007). Adjunct stenting was associated with a significant relative reduction in FIV, with inverse probability of treatment weighting-adjusted analyses demonstrating a 37.8% lower FIV compared with no stenting (β=-0.47 [95% CI, -0.93 to -0.02]; P=0.043). Among 108 patients with baseline computed tomography perfusion data, infarct progression was strongly associated with outcome, with each additional 10 mL associated with ≈25% lower odds of achieving modified Rankin Scale score 0 to 2 at 90 days (adjusted odds ratio, 0.74 [95% CI, 0.60-0.90]; P=0.004), although infarct progression did not differ significantly between stented and nonstented groups (Δ -9.53 mL [95% CI -37.9 to 18.8]; P=0.506). In inverse probability of treatment weighting-weighted models adjusted for successful recanalization, stenting was not independently associated with reduced FIV (β=-0.41; P=0.066), but remained independently associated with higher odds of 90-day functional independence (odds ratio, 2.29 [95% CI, 1.24-4.27]; P=0.008).

CONCLUSIONS: Among intracranial atherosclerosis-related large vessel occlusion patients, 24- to 36-hour FIV is a strong predictor of functional outcome. Adjunct stenting is associated with smaller FIV. Lower infarct progression was also associated with favorable outcome. These findings highlight FIV as a reliable imaging biomarker and potential surrogate end point in future trials.