Effect Modification of Rescue Stenting in ICAS-Related Middle Cerebral Artery Occlusion: The Role of Thrombectomy Failure, Stenosis Severity, and ASPECTS.

Rescue stenting (RS) is increasingly used for intracranial artery stenosis-related large vessel occlusion (ICAS-LVO), but optimal patient selection remains uncertain. We investigated the baseline and procedural factors associated with receiving RS and whether they modified the association between RS and clinical outcome.This retrospective multicenter study included patients with middle cerebral artery (MCA) ICAS-LVO treated with mechanical thrombectomy (MT) alone or MT followed by RS. Baseline and procedural characteristics associated with receiving RS were identified using multivariable logistic regression and incorporated into inverse probability of treatment weighting models to assess treatment-effect heterogeneity for the 90-day modified Rankin Scale score.Among 264 patients, 193 received RS and 71 MT alone. MT failure, severe stenosis (> 75%), and higher baseline Alberta Stroke Program Early CT Score (ASPECTS) were independently associated with receiving RS. Both MT failure (interaction OR 0.28, 95% CI 0.10-0.83; p for interaction = 0.02) and severe stenosis (interaction OR 0.13, 95% CI 0.03-0.53; p for interaction = 0.004) significantly modified the association between RS and clinical outcome, whereas baseline ASPECTS did not. Within the MT failure subgroup, a significant interaction between severe stenosis and ASPECTS was observed (interaction OR 0.08, 95% CI 0.02-0.38; p for interaction = 0.002), suggesting a more favorable association between RS and outcome at higher ASPECTS values in patients with severe stenosis.In MCA ICAS-LVO, RS may be associated with more favorable outcomes in patients with MT failure, particularly in the presence of severe residual stenosis and preserved ASPECTS. These findings support a more selective approach to RS and warrant prospective validation.