Utility of Hypoperfusion Intensity Ratio in Acute Mild Ischemic Stroke With Anterior Circulation Vessel Occlusion

ABSTRACT Objectives Progression of clinical deficits in anterior circulation vessel occlusion strokes (A‐VO) may be attributed to the degree of collateral flow. We investigated the association between hypoperfusion intensity ratio (HIR), a perfusion marker associated with collateral status, and clinical outcomes in mild A‐VO strokes. Methods We conducted a retrospective cohort study of consecutive mild (NIHSS ≤ 5) A‐VO strokes presenting within 24 h and underwent CT perfusion. We dichotomized the sample into high versus low HIR based on the median HIR value and analyzed patients without initial mechanical thrombectomy. The primary outcome was early neurologic deterioration (END), defined as ≥4‐point worsening in baseline NIHSS within 3 days. Secondary outcomes included symptomatic ICH, 3‐month mRS, and mortality. Results We identified 37 patients, and the median HIR was 0.2. We included 17 patients in HIR ≤0.2 and 10 in HIR >0.2 groups. Baseline NIHSS was lower in the HIR ≤0.2 group (2 vs. 4; p = 0.04). Remaining baseline characteristics, IV thrombolytic use, and location of occlusion were similar between groups. There were no between‐group differences in END (3(17.6%) vs. 2(20%), OR 1.16, p = 0.879); 3‐month‐mRS 0–1 adjusted for NIHSS (11 vs. 2, aOR 0.15, p = 0.146); or mortality ( p = 0.178). No patients had symptomatic ICH. Conclusions In our exploratory analysis, mild A‐VO strokes have a lower median HIR (0.2) compared to previously reported HIR (0.4) in moderate‐to‐large strokes. We found no association between HIR and END or functional outcome. Larger prospective studies evaluating the role of HIR in outcome prediction and decision‐making of mild A‐VO strokes are needed.