Abstract 5: CT Perfusion is Not a Treatment Effect Modifier for Mechanical Thrombectomy in the 0-8-Hour-Window: A Pre-Planned Analysis of the RESILIENT Trial

Abstract

Background: CT perfusion has been increasingly used as a selection tool in acute reperfusion therapies. However, it remains unknown whether its use is associated with a higher treatment benefit in patients undergoing thrombectomy. We sought to evaluate the interaction between imaging selection modalities and treatment effect in the RESILIENT Trial. Methods: RESILIENT was a randomized, prospective, multicenter, controlled trial evaluating the safety, efficacy, and cost-effectiveness of thrombectomy versus medical treatment alone in Brazil. A total of 221 patient were enrolled. The trial showed a strong benefit of thrombectomy (90-day mRS ordinal shift, OR 2.28 95%CI [1.41-3.70]; p=0.001). Key imaging selection criteria included ASPECTS ≥6 on non-contrast CT (NCCT) and the exclusion of malignant collateral profile on CT angiography. The use of automated CT perfusion software (RAPID, IschemaView) was optional but was made available in some centers with the pre-specified plan to compare imaging selection modalities. The primary end-point was the common odds ratio (cOR) of mRs at 90 days (shift analysis) and the main secondary endpoint was the rate of functional independence (mRS 0-2) at 90 days. Ordinal logistic and binary regression analyses with imaging selection modality (NCCT versus CTP) as an interaction term were performed with adjustments for potential confounders including age, baseline NIHSS score, occlusion site, IV tPA use and ASPECTS. A p value < 0.05 was considered statistically significant. Results: CTP was performed in 41% of the thrombectomy group and 45% in the control group. There was no significant difference in the treatment effect size for patients selected on the basis of NCCT and CTA only versus those submitted to CTP in terms of overall functional disability (ordinal mRS shift: aOR: 2.87, 95%CI [1.47-5.61] vs. 2.10, 95%CI [1.01-4.36]; p=0.390) or functional independence (mRS 0-2: aOR: 3.16, 95%CI [1.32-7.57] vs. 2.54 95%CI [0.86-7.49], p=0.40) at 90 days. Conclusion: In a randomized clinical trial of thrombectomy within 8 hours of stroke onset, there was no evidence of difference in the treatment effect size across patients selected with NCCT and CTA alone versus automated CT perfusion software.