Comparison Of Risk Factors,Stroke Mechanisms And Infarct Patterns Between Anterior And Posterior Circulation Ischemic Stroke Caused By Intracranial Atherosclerotic Stenosis

Background and purpose:Intracranial atherosclerotic stenosis（ICAS）is a primary contributor to ischemic stroke（IS）.Previous studies have indicated that there were obvious difference between anterior and posterior circulation,including vessels diameter and distribution,blood flow velocity,shear force,collateral circulation.We hypothesized that anterior circulation infarcts originated from ICAS would be different from posterior circulation ones.Therefore,we investigated the differences in risk factors,stroke mechanisms and infarct patterns between anterior and posterior circulation infarct related to ICAS in an attempt to achieve ample data on this kind of infarction in clinical practice.Methods:Cross-sectional study of consecutive patients（age>18years,duration<7d）with MRI-confirmed acute infarct who all were regularly seen throughout their disease course by neurological specialists in the Hospital of Southwest Medical University between December2014 and December 2018.Patients with cerebral hemorrhage,other causes of stroke,or insufficiently detailed clinical information were excluded.After qualifying stroke by MRI,digital subtraction angiography（DSA）was required to confirm artery stenosis（more than fifty percent stenosis rate or occlusion of the responsibility artery）.According to the enrollment requirements,a total of 384 patients were assigned to anterior circulation group（n=246）and posterior circulation group（n=138）.Firstly,based on the basic data and laboratory indicators,risk factors assessment were performed.Secondly,depending on clinical features combining with neuroimaging,stroke mechanisms were classified into artery-to-artery embolism,hemodynamic,local branch occlusion,in situ thrombo-occlusion or multiple mechanisms.At last but not least,relying on the location,size and number of infarcts,infarct patterns were categorized as single lesion（cortical,corticosubcortical,subcortical lesion）,scatter lesion,or multiple lesion.Comparison of stroke mechanisms and infarct patterns between the two groups.Results:（1）Among patients in anterior circulation group,the proportion of male（62.6%）was higher than those in posterior circulation group（50.7%）,while the proportion of hypertension and diabetes（63.0%,35.8%）in anterior circulation group were lower than those of posterior circulation group（79.0%,60.9%）,P<0.05.Posterior circulation group（3.20±1.05）exceeded anterior circulation group（2.89±0.98）in the level of LDL-C,P<0.05.Furthermore,the level of HbA1c in posterior circulation group was 8.31[P₂₅=5.54,P₇₅=9.98],higher than that in anterior circulation group 6.48[P₂₅=5.34,P₇₅=8.91],P<0.05.Logistic regression analysis revealed that hypertension（OR,4.986;95%CI,2.719⁹.143;P<0.001）,diabetes（OR,4.800;95%CI,2.599⁸.863;P<0.001）,the level of LDL-C（OR,1.468;95%CI,1.162¹.854;P=0.001）and HbA1c（OR,1.185;95%CI,1.076¹.305;P=0.001）were independent risk factors for infarcts related to intracranial posterior circulation atherosclerotic stenosis.（2）About stroke mechanisms,artery-to-artery embolism was the most common in anterior circulation group（36.6%）,while local branch occlusion was predominant in posterior circulation group（40.6%）.In addition,the proportion of artery-to-artery embolism（36.6%vs 26.1%）and hemodynamic（8.1%vs 0.7%）in anterior circulation group were respectively higher than those of posterior circulation group,whereas the ratio of local branch occlusion to anterior circulation was lower（14.2%vs 40.6%）,P<0.05.（3）Multiple lesions for anterior circulation（40.7%）was more common,while single subcortical infarction for posterior circulation was more often（40.6%）.Moreover,the rates of single corticosubcortical infarction（17.1%vs 8.7%）and scatter lesion（22.4%vs 10.9%）with anterior circulation group were higher than those of posterior circulation group.On the contrary,the proportion of single subcortical infarction（14.2%vs 40.6%）was lower in the anterior circulation group,P<0.05.Conclusions:Hypertension,diabetes,LDL-C and HbA1c were independent risk factors for posterior circulation infarcts on the basis of ICAS.Artery-to-artery embolism and hemodynamic were dominating in anterior circulation,while local branch occlusion was the major mechanism in posterior circulation.Corticosubcortical lesion and scatter lesion were main in anterior circulation,while subcortical lesion was primary lesion pattern in posterior circulation.Risk factors,stroke mechanisms and lesion patterns differ between anterior and posterior circulation stroke with ICAS.In order to reduce the recurrence of stroke,prevention and treatment strategies might vary with infarction subtypes.