# Relationship of ASPECTS Lesion Topography with Clinical Outcomes in Acute Ischemic Stroke Treated with Endovascular Thrombectomy: A Single-Center Cohort Study

## TL;DR

This study finds that specific brain regions affected by stroke, like the internal capsule and M1 region, are strongly linked to poor recovery outcomes after endovascular treatment, even when overall stroke severity is considered.

## Contribution

The study identifies specific ASPECTS regions (internal capsule and M1) as independent predictors of poor outcomes in stroke patients undergoing endovascular thrombectomy.

## Key findings

- Involvement of the internal capsule and M1 region in ASPECTS is strongly associated with poor clinical outcomes.
- Internal capsule involvement remains an independent predictor of poor outcomes even after successful recanalization.
- Regional ASPECTS localization alone is not sufficient for selecting patients for endovascular thrombectomy.

## Abstract

Objective: Although an Alberta Stroke Program Early CT Score (ASPECTS) < 7 is known to be associated with poor clinical outcomes in patients with acute ischemic stroke (AIS), the relationship between regional differences in infarct location within the ASPECTS territory and clinical outcome has not been fully clarified. The aim of this study is to evaluate the association between infarct area localization and clinical outcomes in AIS patients with large vessel occlusion and to investigate whether these regional patterns can be used to predict prognosis independently of the total ASPECTS. Methods: In this retrospective, single-center study, patients with acute ischemic stroke who had undergone non-contrast brain CT prior to endovascular thrombectomy between January 2020 and July 2023 and were found to have internal carotid artery (ICA) and/or middle cerebral artery (MCA) M1 segment occlusion were included. Patients with a premorbid modified Rankin Scale (mRS) score of 0–2 were eligible for inclusion. Patients with unavailable imaging or clinical follow-up data were excluded. Clinical outcomes were assessed using the modified Rankin Scale at 90 days. An mRS score of 0–2 was defined as a good clinical outcome, whereas an mRS score of 3–6 was defined as a poor clinical outcome. Results: A total of 283 patients were included (median age 73 years; 57.2% female), of whom 147 (51.9%) achieved a good clinical outcome. The poor outcome group had higher NIHSS scores and lower total ASPECTS values (both p < 0.001). In the regional analysis, involvement of the internal capsule (32.4% vs. 4.1%; p < 0.001) and ASPECTS M1 region (26.5% vs. 10.2%; p < 0.001) was associated with poor outcome. In multivariable analysis, internal capsule involvement (adjusted odds ratio [aOR] ≈ 12) and M1 region involvement (aOR ≈ 2.7) remained independent predictors. In the subgroup with successful recanalization, only internal capsule involvement remained an independent predictor (aOR ≈ 19). In hemisphere-stratified analyses, M1 involvement in the right hemisphere and internal capsule involvement in the left hemisphere were independently associated with poor outcome. Conclusions: The prognostic contribution of individual ASPECTS regions is not uniform in patients with acute ischemic stroke undergoing endovascular thrombectomy (EVT). In particular, involvement of the internal capsule and the M1 region shows a strong association with poor clinical outcome independent of the total ASPECTS. However, these findings suggest that regional localization alone is not sufficient for EVT patient selection. Further large-scale, multicenter studies are needed to clarify the role of regional ASPECTS assessment in clinical decision-making.