Association of Infarct Topography and Outcome After Endovascular Thrombectomy in Patients With Acute Ischemic Stroke

Background and Objectives: The care of patients with large vessel occlusion (LVO) stroke has been revolutionized by endovascular thrombectomy (EVT). While EVT has a large effect size, most patients treated with EVT remain disabled or die within 90 days. A better understanding of outcomes may influence EVT selection criteria, novel therapies, and prognostication. We sought to identify associations between outcomes and brain regions involved in ischemic lesions. Methods: For this cohort study, consecutive patients with LVO who were treated with EVT and underwent post-EVT MRI were identified from a tertiary referral center (2011-2019). Acute ischemic lesions were manually segmented from DWI and spatially normalized. Individual lesions were parcellated (atlas-defined 94 cortical regions, 14 subcortical nuclei, 20 white matter tracts) and reduced to ten essential lesion patterns using unsupervised dimensionality reduction techniques. Ninety-day modified Rankin Scale (mRS>2) was modeled via Bayesian regression, taking the ten lesion patterns as inputs, and controlling for lesion size, age, sex, acute NIH Stroke Scale (NIHSS), alteplase, prior stroke, intracerebral hemorrhage, and good reperfusion (TICI2b-3). In comparative analyses, 90-day mRS was modeled considering covariates and compartment-wise relevance for acute stroke severity and 90-day mRS were evaluated. Results: There were 151 patients with LVO identified (age: 68±15 years; 52% female). The median NIHSS was 16 (IQR 13-20); 56% had mRS>2. Lesion locations predictive of 90-day mRS involved bilateral, but left-hemispherically more pronounced pre- and postcentral gyri, insular and opercular cortex, as well as left putamen and caudate (area under the curve: 0.91, highest probability density interval (HPDI) covering 90%-certainty: 0.90–0.92). The lesion location model outperformed the simpler model relying on covariates only (Bayesian model comparison of weight: 97% to the model with vs. 3% to that without lesion location). While lesions affecting subcortical nuclei had the highest relevance for stroke severity (posterior distribution mean: 0.75, 90%-HDPI=0.256–1.31), lesions affecting white matter tracts had the highest relevance for 90-day mRS (0.656, 90%-HDPI=0.0864–1.12). Discussion: These data describe the significance for outcomes of specific brain regions involved in ischemic lesions on MRI after EVT. Future work in additional datasets is needed to confirm these granular findings.