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Background and aims Acute silent ischemic lesions (ASILs) usually present as diffusion weighted imaging hyperintensity with corresponding apparent diffusion coefficient hypointensity, indicating a possibly unstable ischemic pattern in severe intracranial stenosis. However, there is still no conclusive evidence that preprocedural ASILs are associated with inhospital stroke after percutaneous transluminal angioplasty and stenting (PTAS).Methods A single center retrospective cohort study was conducted among patients with severe symptomatic intracranial atherosclerotic stenosis (severe sICAS) who underwent PTAS at a tertiary care center between January 2019 and October 2024. Among 1727 initially screened patients, 1427 eligible patients were included according to preprocedural ASIL status. The primary endpoint was prespecified as stroke or death during the index hospitalization. Multivariable logistic regression was used to evaluate the association between ASILs and the primary endpoint. Sensitivity analyses included propensity score matching, inverse probability of treatment weighting using winsorized stabilized weights, doubly robust weighted modeling using the same winsorized stabilized weights, Firth penalized logistic regression, early period exclusion analyses, and parsimonious models addressing events-per-variable concerns. Apparent within cohort discrimination and reclassification were assessed by the area under the receiver operating characteristic curve, DeLong test, continuous net reclassification improvement, and integrated discrimination improvement.Results Of the 1427 participants, 60 (4.2%) had the primary endpoint, all of which were inhospital stroke events; no inhospital deaths occurred. Preprocedural ASILs were associated with inhospital stroke in univariable analysis (OR 4.62, 95% CI 2.68 to 7.98; P<0.001) and remained independently associated with inhospital stroke in the prespecified multivariable model (OR 5.00, 95% CI 2.70 to 9.26; P<0.001). The association remained consistent in propensity score matching (OR 4.20, 95% CI 1.58 to 11.14; P=0.004), inverse probability of treatment weighting using winsorized stabilized weights (OR 3.94, 95% CI 2.16 to 7.18; P<0.001), doubly robust weighted modeling using the same winsorized stabilized weights (OR 4.12, 95% CI 2.26 to 7.52; P<0.001), and Firth penalized logistic regression (OR 4.72, 95% CI 2.57 to 8.56; P<0.001). Adding ASIL status to the prespecified clinical model increased the apparent AUC from 0.705 to 0.763 (DeLong P=0.010) and improved reclassification.Conclusions Preprocedural ASILs were independently associated with inhospital stroke after PTAS in patients with severe sICAS. Incorporation of ASIL status into a prespecified clinical model was associated with improved apparent within cohort discrimination and reclassification, but external validation is required before clinical application.