Venous Outflow And Futile Recanalization After Endovascular Treatment In Stroke Patients With Large Artery Occlusion

Background and purpose:Endovascular treatment(EVT)can significantly improve the prognosis of stroke patients due to large artery occlusion.Approximately 50%of patients still have a unfavarable outcome at 3 months after successful vessel racanalization.This condition is termed as futile recanalization.So far,the pathophysiological mechanism of futile recanalization is not completely elucidated.Unfavarable collateral status may be a major determinant forfutile recanalization.Arterial collaterals reflect blood flow into the ischemic lesion but not the overalltissue perfusion.At present,the relationship between arterial collateral status and the outcome after EVT is still controversial.Recent studies paied much attention to the role of venous collaterals in reperfusion of stroke patients.The study aimed to assessed the correlation between venous outflow profiles and futile recanalization in patients treated with EVT based on computed tomography perfusion(CTP).Methods:Stroke patients with acute anterior circulation large artery occlusionwere enrolled consecutively from Mianyang Central Hospital between March 2020 to January 2022.Patients withsuccessful recanalization,defined as a modifed thrombolysis in Cerebral Infarction Score(mTICI)of 2b or 3 were analyzed.Non-contrast head CT(NCCT)and CTP were performed within 30 minutes after admission.Follow-up cranial CT and MRI were performed within 72 hours of EVT.The first chapter included patients from March 2020 to July 2021,among which patients without hemorrhagic transformation or contrast medium leakage after EVT were the subjects of the third chapter.Patients whose perfusion images processed by RAPID software from January 2021 to January 2022 were included in the second chapter.Peak time of venous outflow(PTV)and difference value of arteriovenous peak time(D-value)were calculated based on time-intensity curves of artery and vein derived from CTP.Ischemic lesion net water uptake(NMU)after EVT was calculated using CT density method.Based on the multiphase computed tomography angiography(mCTA)reconstructed from CTP,the opacification extents of the corresponding veins on the ischemic side were evaluated semiquantitatively,taking the optimal opacification extents of superficial cerebral vein,Labbé vein and sphenoparietal sinus on the normal side as reference.The assignment method was as follows:0,not visible;1,moderate opacification;2,full opacification.The total score was defined as multiphase cortical vein opacification score(mCOVES).Futile recanalization was defined as 90-day modified Rankin Scale of 3-6.Favarable tissue-level collaterals was defined as hypoperfusion intensity ratio≦0.4.Binary logistic stepwise regression was used to identify the independent related factors for futile recanalization.The logistic regression was performed to identify the independent related factorsfor favarable tissue-level collaterals.Multiple linear regression analysis was used to explore the factors related to NWU of ischemic lesion after EVT.Results:1.In chapter 1,a total of 80 patients were inclueded.45(56.3%)developed futile recanalization.12(15%)developed hemorrhagic transformation.4(5%)had contrast medium leakage in the affected side.Compared with patients with useful recanalization,PTV was prolonged in patients with futile recanalization(13.5 vs 12,P<0.001).Binary logistic stepwise regression analysis showed that PTV was an independent related factor for futile recanalization(OR=1.496,95%CI:1.169-1.916,P=0.001).Stratified by arterial collateral status,there were 34(42.5%)patients with favarable arterial collaterals and 46(57.5%)patients with unfavarable arterial collaterals.Binary logistic stepwise regression analysis showed that PTV was related to futile recanalization independently regardless of favarable arterial collateral status(OR=1.753,95%CI:1.128-2.726,P=0.013)or unfavarable arterial collateral status(OR=1.389,95%CI:1.030-1.872,P=0.031).Taking 64 patients without posttreatment hemorrhage transformation or contrast medium leakage as the subgroup,binary logistic stepwise regression analysis showed that NWU of ischemic lesion after EVT(OR=1.111,95%CI:1.016-1.215,P=0.021)was associated with futile recanalization independently.Multiple linear regression analysis showed that NWU of ischemic lesion after EVT was positively related to PTV(β=1.304,P<0.001)and final infarct volume(β=0.049,P=0.002).2.In chapter 2,a total of 89 patients were included.44(49.4%)had favarable tissue-level collaterals.Compared with patients with unfavarable tissue-level collaterals,PTV was shorter in patients with favarable tissue-level collaterals(12 vs 16.5,P<0.001).Binary logistic stepwise regression analysis showed that PTV(OR=0.751,95%CI:0.589-0.958,P=0.021)was associated with tissue-level collaterals.3.In chapters,there were 64 subjects.34(53.1%)developed futile recanalization.Compared with patients with useful recanalization,mCOVES was lower in patients with futile recanalization(1 vs 3,P<0.001).Binary logistic stepwise regression analysis showed that mCOVES was significantly associated with futile recanalization(OR=0.424,95%CI:0.256-0.702,P=0.001).ConclusionRegardless of arterial collateral status,delayed PTV increases the risk of futile recanalization after EVT in stroke patients due to acute anterior circulation large artery occlusion,which is related to tissue-level collaterals.Both mCOVES and PTV can predict futile recanalization.NMU of ischemic lesion after EVT,final infarct volume and atrial fibrillation were independent related factors of unfavarable cortical venous outflow.