Abstract Body: Background: For patients with an intra-cranial ICA, M1 or M2 vessel occlusion (ACLVO) initially presenting to non-thrombectomy centers, a CT Perfusion collateral score derived from the CRISP2 study cohort based on the HIR and CBVI obtained at the non-thrombectomy center, has been associated with fast infarct growth and functional outcome, but further validation is needed.
Methods: We conducted a retrospective study from our stroke network of patients with an ACLVO who underwent CTP scanning (Rapid Software, iSchemaView, Inc., ver 5.5) at a non-thrombectomy center and were subsequently transferred for consideration of thrombectomy. We evaluated the association of three measures of collateral status (HIR, CBVI and the CRISP2 score as depicted in figure1) to 90-day mRS.
Results: From December 2016 to March 2024, a total of 438 patients with a diagnostic quality CTP, a median age of 70 years (IQR 59-80) and a baseline NIH Stroke Scale score of 15 (IQR 9-20) were included, of whom 92% underwent thrombectomy, with a median CTP to arterial puncture time of 109 minutes (IQR 94-129). Among all patients, HIR (both numerical and dichotomized at both <0.5 or <0.4) was not associated with good functional outcome (90-day mRS 0-2) nor a significant shift toward good functional outcome. The CRISP2 collateral score was associated with a significant shift, but not with good functional outcome. CBVI (both numerical and dichotomized at 0.7), predicted both good functional outcome and a shift toward good functional outcome (see univariate results table). After adjusting for covariates, CRISP2 lost significance in predicting 90-day mRS, while CBVI remained significantly associated with outcome (see multivariate results table). Similar results were seen when limiting the study population to patients achieving recanalization (n=385), defined as a post-thrombectomy TICI score of ≥2B.
Conclusion: Our study of a large cohort of ACLVO patients transferred for thrombectomy did not find a significant association of HIR and the CRISP2 collateral score with good functional outcome, but did for CBVI. Among CTP measures of collateral status, CBVI alone may play an important role in stroke prognostication and management for ACLVO patients initially presenting to non-thrombectomy centers. Additionally, a favorable CBVI may help identify ACLVO patients to target for future cytoprotective trials when interfacility transfer is required for thrombectomy.