Abstract WP99: Impact Of Venous Delay Evaluated Before And After Mechanical Thrombectomy On Stroke Outcome

Introduction: We aimed to evaluate venous delay before and after treatment as a marker of radiological and clinical outcome in stroke patients receiving endovascular treatment (EVT). Methods: Prospective cohort of patients with anterior intracranial occlusion undergoing EVT. Brain MRI was performed on arrival (pre-EVT), <2h after EVT (post-EVT), and 5 days after stroke. Final infarct volume was segmented on DWI at 5 days. We evaluated the veins of Labbé, Trolard and the superficial middle cerebral vein at both hemispheres on the dynamic MR angiography (dmRA) pre-EVT and post-EVT. For each vein we calculated a standardized venous delay measure:[(time to maximum venous contrast filling in the healthy hemisphere-time to maximum venous contrast filling in the affected hemisphere)/time to maximum venous contrast filling in the healthy hemisphere]x100. We defined venous delay as the value of the most delayed vein in each patient. We assessed the association between venous delay pre-EVT and post-EVT and final infarct volume and modified Rankin Scale (mRS) at 90 days, using multivariable regressions adjusted by successful reperfusion (mTICI≥2b) and other relevant variables. Results: From 98 included patients (median NIHSS 17, final mTICI≥2b 86%), 89 pre-EVT dMRIs and 88 post-EVT dMRIs were evaluable. The median venous delay pre-EVT and post-EVT were -31.9[-58.1;-16.7]% and -13.5[-34.5;-7.5]%, respectively. Venous delay pre-EVT was not related to infarct volume or clinical outcome. When final mTICI≥2B, venous asymmetry decreased but still persisted. For each 10% of increment in venous delay post-EVT, there was an adjusted increase of 0.12[0.05-0.19]ml in the final infarct volume. Venous delay post-EVT was independently associated with mRS at 90 days (cOR 1.013 [95%CI 1.001-1.0256]). Conclusion: Cortical vein delay assessed after but not before EVT, is associated with a larger final infarct volume and with a worse clinical outcome.