Perfusion imaging-guided risk stratification and endovascular decision-making in low-NIHSS large-vessel occlusion stroke: a systematic review and exploratory meta-analysis.

BACKGROUND: Patients with acute ischemic stroke due to large-vessel occlusion (LVO) may present with low National Institutes of Health Stroke Scale (NIHSS) scores, creating uncertainty regarding the need for endovascular therapy. Perfusion imaging may help identify patients at high risk for early neurological deterioration (END), but its clinical utility in this population remains unclear. METHODS: We performed a systematic review and exploratory meta-analysis of studies evaluating perfusion or hemodynamic imaging in adults with low-NIHSS LVO stroke. PubMed, Embase, Scopus, Web of Science, and the Cochrane Library were searched from inception to June 2026. Eligible studies reported associations between perfusion imaging markers and END or functional outcome, or evaluated imaging-informed endovascular decision-making. Random-effects models were used for exploratory pooled analyses. Risk of bias was assessed using QUIPS and ROBINS-I-informed domains, and certainty of evidence was evaluated using GRADE. RESULTS: The search identified 1698 records, of which 1372 remained after removal of duplicates. The evidence base included perfusion risk-stratification studies, endovascular decision-making studies, background reviews and meta-analyses, and ongoing trial protocols. Larger Tmax-defined hypoperfusion volumes, larger perfusion lesion volumes, and impaired hemodynamic reserve were associated with early neurological deterioration or poor functional outcome. In three studies eligible for exploratory pooling, a high-risk perfusion phenotype was associated with early neurological deterioration or deterioration of ischemic origin (pooled odds ratio, 6.55; 95% confidence interval, 1.65-25.99; I2≈78%). Two studies suggested an association with poor functional outcome (pooled odds ratio, 9.24; 95% confidence interval, 1.99-42.99; I2≈66%). Evidence regarding perfusion-guided endovascular therapy was heterogeneous and observational. CONCLUSIONS: In low-NIHSS LVO stroke, perfusion and hemodynamic imaging identifies a high-risk tissue-at-risk phenotype associated with neurological deterioration and poor outcome. However, evidence supporting perfusion-guided endovascular therapy remains uncertain. Randomized trials are required to define whether imaging-based selection improves outcomes in this population.