Clinical predictor of volume hypoperfusion in patients treated with extended window mechanical thrombectomy: an external validation study.

Introduction: Treatment of ischemic stroke has expanded beyond the 6-hour window, but identification of eligible patients requires advanced imaging, which is often unavailable. This study aimed to validate a prediction model using the NIHSS score (a measure of stroke severity) to estimate hypoperfusion volume and determine eligibility for DEFUSE 3 treatment criteria.

Materials and methods: Data from ischemic stroke patients with less than 24 hours' evolution were analyzed. A previously developed prediction rule based on the NIHSS score was used to estimate the volume of hypoperfused tissue with Tmax>6s, a marker for eligibility for the DEFUSE 3 treatment criteria. This estimated volume was compared with actual perfusion volumes obtained by magnetic resonance imaging or computed tomography with AI segmentation. Sensitivity, specificity and predictive values for determining DEFUSE 3 eligibility were calculated.

Results: Sixty-one patients were included (age: 71.9 ± 14.8 years, female: 60%, NIHSS: 16.5 ± 7.4 points). The prediction rule showed high accuracy in determining DEFUSE 3 eligibility with a sensitivity of 0.96, specificity of 0.93, positive predictive value of 0.98 and negative predictive value of 0.87.

Discussion: Estimating hypoperfusion volume directly from the NIHSS score using a simple prediction rule provides a reliable and readily available method for identifying patients potentially eligible for DEFUSE 3 treatment. Rapid and reliable estimation of hypoperfusion volume could improve access to advanced stroke care in settings with limited imaging resources.