Abstract WP34: Associations Between CTP Ischemic Core Volume, ASPECTS Scores and Clinical Outcomes After Endovascular Reperfusion

Abstract

Introduction: ASPECTS and CT perfusion (CTP) lesion volumes have been used to triage patients with large artery occlusions to endovascular therapy. Specifically, ASPECTS ≤5 and CTP infarct core >50 mL excluded patients from some recent endovascular trials. It is unclear how well these criteria select patients who will have poor functional outcomes despite reperfusion and if the criteria are interchangeable. Hypothesis: ASPECTS and CTP infarct volumes are correlated and both predict clinical outcome. Methods: Patients with anterior circulation strokes were enrolled in a prospective multi-center study (CRISP) if CTP could be obtained <90 minutes before endovascular treatment, and intervention performed <18h from onset. Reperfusion was defined as >50% reduction from baseline Tmax>6s volume on early follow-up MRI (<36h from baseline CT) or final TICI 2b/3 if follow-up MRI unavailable. A single blinded reader at the core imaging facility determined ASPECTS on baseline CT. Baseline ischemic core volumes were assessed using automated software (RAPID). Good outcome was defined as mRS 0-2 and poor outcome as mRS 5-6. Results: This analysis includes 165 patients with reperfusion after endovascular therapy. Baseline ASPECTS and infarct core volume are inversely associated (p=0.009). Lower ASPECTS and larger infarct core were associated with a lower chance of good outcome in univariate analysis: OR for good outcome was 0.8 (95% CI 0.7-1.0) per point decrease in ASPECTS and 0.8 (95% CI 0.6-0.9) per 10mL increase in infarct core. Adjusted for baseline NIHSS and age, core remained a predictor of good outcomes (p=0.025) while ASPECTS showed a strong trend (p=0.072). The PPV for poor outcome despite reperfusion was 38% (5/13) for infarct core >50 mL and 0% (0/7) for ASPECTS ≤5 (p=0.1 for difference in PPV). No patient met both criteria. Conclusions: The ASPECTS and ischemic core volume criteria used to exclude patients from some endovascular therapy trials, did not agree in identifying patients with presumed poor outcomes. Neither criterion had a high specificity for identifying patients destined to have a poor outcome despite reperfusion. Randomized trials are warranted to assess the efficacy of endovascular therapy in patients with ischemic core lesions >50 ml and ASPECTS ≤5.