Internal Capsule Involvement Explains the Prognostic Impact of ASPECTS after Endovascular Thrombectomy for Large-Core...

The prognostic implications of Alberta Stroke Program Early CT Score (ASPECTS) subscores in patients with large-core ischemic stroke undergoing endovascular thrombectomy (EVT) remain uncertain. We hypothesized that specific ASPECTS regions substantially influence functional outcomes after EVT and therefore sought to identify which individual subscores are associated with outcome and whether any of them account for the association between total ASPECTS and functional outcomes. We retrospectively analyzed patients with large-core ischemic stroke (ASPECTS ≤ 5) who underwent EVT. Multivariate logistic regression identified factors associated with functional outcomes, and mediation analysis assessed whether specific ASPECTS subscores explains the effect of total ASPECTS on outcomes. Among 295 patients (median ASPECTS 4), 49.2% had a median mRS score of 3 at 3 months. Internal capsule (IC) involvement was the only subscore significantly associated with worse outcomes, including ordinal mRS shift (Odds ratio 2.03 [ 95% confidence interval 1.19‒3.46], P = 0.009), mRS ≥ 4 (3.01 [1.45‒6.24], P = 0.003), and mRS ≥ 3 (2.24 [1.03‒4.87], P = 0.042). Mediation analysis showed that IC involvement explained 50.6% of the total ASPECTS effect on outcomes. Patients with IC lesions showing reversal on follow-up imaging had a significantly lower risk of poor outcomes (0.28 [0.09-0.80], P = 0.018). IC involvement independently predicts poor outcomes after EVT for large-core stroke and substantially explains the effect of total ASPECTS on prognosis.