Mechanical Thrombectomy in Patients with Acute Ischemic Stroke and Lower NIHSS Scores: Recanalization Rates,Periprocedural Complications,and Clinical Outcome

BACKGROUND AND PURPOSE:Mechanical thrombectomy, in addition to intravenous thrombolysis, has become standard in acute ischemic stroke treatment in patients with large-vessel occlusion in the anterior circulation. However, previous randomized controlled stroke trials were not focused on patients with mild-to-moderate symptoms. Thus, there are limited data for patient selection, prediction of clinical outcome, and occurrence of complications in this patient population. The purpose of this analysis was to assess clinical and interventional data in patients treated with mechanical thrombectomy in case of ischemic stroke with mild-to-moderate symptoms.MATERIALS AND METHODS:We performed a retrospective analysis of a prospectively collected stroke data base. Inclusion criteria were anterior circulation ischemic stroke treated with mechanical thrombectomy at our institution between September 2010 and October 2015 with an NIHSS score of ≤8.RESULTS:Of 484 patients, we identified 33 (6.8%) with the following characteristics: median NIHSS = 5 (interquartile range, 4–7), median onset-to-groin puncture time = 320 minutes (interquartile range, 237–528 minutes). Recanalization (TICI = 2b–3) was achieved in 26 (78.7%) patients. Two cases of symptomatic intracranial hemorrhage were observed. Favorable (mRS 0–2) and moderate (mRS 0–3) clinical outcome at 90 days was achieved in 21 (63.6%) and 30 (90.9%) patients, respectively.CONCLUSIONS:The clinical outcome of patients undergoing mechanical thrombectomy for acute ischemic stroke with mild stroke due to large-vessel occlusion appears to be predominately favorable, even in a prolonged time window. However, although infrequent, angiographic complications could impair clinical outcome. Future randomized controlled trials should assess the benefit compared with the best medical treatment.

In several randomized multicenter stroke trials, mechanical thrombectomy has proved to be an effective treatment for large intracranial vessel occlusion in patients with acute ischemic stroke in the anterior circulation.^1–5 With the exception of the Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands (MR CLEAN) trial⁴ and Extending the Time for Thrombolysis in Emergency Neurological Deficits–Intra-Arterial (EXTEND-IA),¹ all of those stroke trials did not include patients with minor-to-moderate stroke symptoms but focused on patients with a moderate or severe stroke with a score of at least 6–8 or higher on the National Institutes of Health Stroke Scale. Consequently, the median NIHSS score for patients who underwent mechanical thrombectomy was about 15–17 in all trials; including the MR CLEAN und EXTEND-IA trials.Large intracranial vessel occlusions are not necessarily associated with a high baseline NIHSS score and could be missed in patients with low NIHSS scores.⁶ In a large single-center cohort, 72% of the patients presenting with mild stroke symptoms did not undergo advanced stroke imaging (eg, CT angiography or CT perfusion) before intravenous thrombolysis. However, visualization of a possible proximal occlusion is essential for further treatment decisions. If thrombus length exceeds 8 mm, intravenous thrombolysis has almost no potential to recanalize the occluded vessel.^7,8 The chance for a good clinical outcome (mRS 0–2) is only 7.7% in such cases.⁷ Furthermore, despite intravenous thrombolysis, mortality is 1.3%, and 30.3% of the patients who presented with mild initial stroke symptoms could not ambulate independently at discharge.⁹Even though the complication rate in mechanical thrombectomy is low, the clinical benefit for the patient has to outperform the cost and potential risks. Here, we assessed the outcome of patients with acute ischemic minor-to-moderate stroke who underwent mechanical thrombectomy at our institution. We present data on the location of occlusions, thrombus length, collateral status, recanalization rates, periprocedural complications, and clinical outcome.     

Mechanical Thrombectomy in Nighttime Hours: Is There a Difference in 90-Day Clinical Outcome for Patients with Ischemic Stroke?

BACKGROUND AND PURPOSE:Few data are available regarding the influence of the timing of ischemic stroke management, such as daytime and nighttime hours, on the delay of mechanical thrombectomy, the effectiveness of revascularization, and clinical outcomes. We aimed to investigate whether admission during nighttime hours could impact the clinical outcome (mRS at 90 days) of patients with acute ischemic stroke treated by mechanical thrombectomy.MATERIALS AND METHODS:We retrospectively analyzed 169 patients (112 treated during daytime hours and 57 treated during nighttime hours) with acute ischemic stroke in the anterior cerebral circulation. The main outcome was the rate of patients achieving functional independence at 90 days (mRS ≤2), depending on admission time.RESULTS:In patients admitted during nighttime hours, the rate of mRS ≤ 2 at 90 days was significantly higher (51% versus 35%, P = .05) compared with those admitted in daytime hours. Patients in daytime and nighttime hours were comparable regarding admission and treatment characteristics. However, patients in nighttime hours tended to have a higher median NIHSS score at admission (P = .08) and to be younger (P = .08), especially among the mothership group (P = .09). The multivariate logistic regression analysis confirmed that patients in nighttime hours had better functional outcomes at 90 days than those in daytime hours (P = .018; 95% CI, 0.064–0.770; OR = 0.221).CONCLUSIONS:In a highly organized stroke care network, mechanical thrombectomy is quite effective in the nighttime hours among acute ischemic stroke presentations. Unexpectedly, we found that those patients achieved favorable clinical outcomes more frequently than those treated during daytime hours. Larger series are needed to confirm these results.

Blood flow restoration is the principal therapeutic goal in acute ischemic stroke (AIS). IV rtPA is recommended for all eligible patients within 4.5 hours of of symptoms onset. For patients with AIS with acute large-vessel occlusion, mechanical thrombectomy (MT) is highly beneficial and recommended as a standard of care.¹ Functional outcomes are better when the MT is performed early after stroke onset.²The impact of admission hours on short-term prognosis of patients with AIS is still controversial. Some series investigated whether patients with AIS admitted during off-hours (Monday to Friday between 6 PM and 8 AM and weekends) had different outcomes compared with patients admitted during on-hours. One study reported that patients in off-hours had higher short-term mortality, greater disability at discharge, and worse outcomes at 90 days than patients admitted during working hours.³ Conversely, another study suggested that rates of poor 90-day outcomes (mRS >2) were similar between off- and on-hours admissions.⁴Furthermore, in a recent large cohort of Dutch patients, the overall outcome was not influenced by time of admission.⁵ Results of these studies may be influenced by local stroke center organization and may not be generalized to other centers with different organizations.The only study focusing on the outcomes after MT performed during on-versus-off hours was a recent analysis of the Multicenter Randomized CLinical trial of Endovascular treatment for Acute ischemic stroke in the Netherlands (MR CLEAN) registry group (https://mrclean-trial.org/), which showed comparable functional outcomes and complication rates among the 2 groups.⁶Accordingly, outcomes after MT performed during working hours versus off-hours have not been accurately examined and require further research.Night presentation and sleep deprivation have been reported as potential risk factors for patients presenting with unplanned critical illness and requiring rapid diagnostics and interventions.⁷ This can cause worse outcome in these patients, that can be attributed to increased complications, fatigue, and differential staffing.⁸ Accordingly, our hypothesis was that performance of the workflow and operators could be impacted during the night, reflecting worse outcomes after MT performed during nighttime hours. In addition, our institution (Millau hospital, Mende hospital and Perpignan hospital) receives patients with stroke from a 200-km perimeter; therefore, delay in transportation may negatively influence outcomes. We hypothesized that transport delays could be higher during nighttime hours compared with daytime hours due to less availability of helicopter transport at night. We aimed to investigate whether admission during nighttime hours could impact the clinical outcomes (in-hospital mortality and mRS at 90 days) of patients with AIS treated by MT.     

Differential Contribution of ASPECTS Regions to Clinical Outcome after Thrombectomy for Acute Ischemic Stroke

BACKGROUND AND PURPOSE:Ischemic stroke is the leading cause of long-term disability in adults, but our ability to prognosticate from baseline imaging data is limited. The ASPECTS measures ischemic change in the middle cerebral artery territory on noncontrast CT based on 10 anatomic regions. Here, we investigated whether infarction in particular regions was associated with worse long-term outcome.MATERIALS AND METHODS:We identified consecutive patients receiving mechanical thrombectomy for ICA/MCA occlusion at 2 comprehensive stroke centers. Pretreatment ASPECTS was assessed by 2 blinded reviewers. Clinical data including demographics, baseline NIHSS score, and 90-day mRS were collected. The relationship between individual ASPECTS regions and the mRS score (0–2 versus 3–6) was assessed using multivariable logistic regression.RESULTS:Three hundred fifty-three patients were included (mean age, 70 years; 46% men), of whom 214 had poor outcome (mRS = 3–6). Caudate (OR = 3.26; 95% CI, 1.33–8.82), M4 region (OR = 2.94; 95% CI, 1.09–9.46), and insula (OR = 1.75; 95% CI, 1.08–2.85) infarcts were associated with significantly greater odds of poor outcome, whereas M1 region infarction reduced the odds of poor outcome (OR = 0.38; 95% CI, 0.14–0.99). This finding remained unchanged when restricted to only patients with good recanalization. No significant associations were found by laterality. Similarly, no region was predictive of neurologic improvement during the first 24 hours or of symptomatic intracerebral hemorrhage.CONCLUSIONS:Our results indicate that ASPECTS regions are not equal in their contribution to functional outcome. This finding suggests that patient selection based on total ASPECTS alone might be insufficient, and infarct topography should be considered when deciding eligibility for thrombectomy.

Recent advances in the field of endovascular thrombectomy have led to a sea change in the management of large-vessel-occlusion acute ischemic stroke, with several initial trials showing benefit with new-generation endovascular approaches.^1-6 The time window for thrombectomy has subsequently expanded to up to 24 hours from onset.^7,8 In all these trials, imaging was crucial to identify patients likely to benefit. Most trials in 2015 used lesion size on CT as part of their selection criteria, quantified as the ASPECTS. ASPECTS was first described in 2000 and separates the middle cerebral artery territory into 10 regions (6 superficial, 4 deep; Figure). These are then assigned a value of 0 if there are early ischemic changes—parenchymal hypoattenuation, loss of gray-white differentiation, and focal swelling—and a value of 2 if the region is normal in appearance.⁹ Correspondingly, lower scores imply more extensive ischemia and intuitively suggest that the outcome is more likely to be poor; indeed, the ASPECTS is known to have value in long-term prognostication after stroke,¹⁰ and has previously been shown to correlate with functional independence in intra-arterial thrombolysis.¹¹ Thus, low ASPECTS values continue to be used as an exclusion criterion for thrombectomy because these patients are assumed to have a low likelihood of meaningful improvement.Open in a separate windowFIGURE.Illustration of ASPECTS, showing 10 regions in 1 hemisphere. C indicates caudate; IC, internal capsule; L, lentiform; I, insula. Reproduced from Neuhaus et al²⁵ with permission from BMJ Publishing Group Ltd.However, there are a number of disadvantages in using ASPECTS. First, although it significantly correlates with long-term function on a group level, individual outcomes are discriminated less accurately, particularly when the ASPECTS is moderate to high (eg, 6–10, implying limited ischemic change).¹² Second, it is known that involvement of specific regions leads to particular functional deficits, eg, the angular gyrus in language¹³ and multiple cortical and subcortical areas in motor function.¹⁴ The ASPECTS treats all 10 areas equally; therefore, a composite ASPECTS of 7 may reflect very different lesion patterns, and there is no a priori reason to think these would be equivalent in terms of functional consequences. Third, the volumes of ASPECTS regions are not equal, and the loss of a single point can reflect a wide range of ischemic volumes, depending on which areas are affected. Indeed, it has been previously reported that some regions confer a greater risk of poor long-term outcome.¹⁵ Variation in outcome based on the affected area has also been described with ASPECTS regions from baseline CT,^15-18 though with inconsistent findings.The implication of this finding is that a significant number of patients with a poor composite ASPECTS might, in fact, have a greater likelihood of good outcome than the total score would suggest, which may influence treatment decisions. In this study, we sought to estimate regional contributions to long-term function using pretreatment ASPECTS data in a thrombectomy cohort.     

CTA Collateral Status and Response to Recanalization in Patients with Acute Ischemic Stroke

BACKGROUND AND PURPOSE:Collateral status at baseline is an independent determinant of clinical outcome among patients with acute ischemic stroke. We sought to identify whether the association between recanalization after intra-arterial acute stroke therapy and favorable clinical response is modified by the presence of good collateral flow assessed on baseline CTA.MATERIALS AND METHODS:Data are from the Keimyung Stroke Registry, a prospective cohort study of patients with acute ischemic stroke from Daegu, South Korea. Patients with M1 segment MCA with or without intracranial ICA occlusions on baseline CTA from May 2004 to July 2009 who also had baseline MR imaging were included. Two readers blinded to all clinical information assessed baseline and follow-up imaging. Leptomeningeal collaterals on baseline CTA were assessed by consensus by use of the regional leptomeningeal score.RESULTS:Among 84 patients (mean age, 65.2 ± 13.2 years; median NIHSS score, 14; interquartile range, 8.5), median time from stroke onset to initial MR imaging was 164 minutes. TICI 2b–3 recanalization was achieved in 38.1% of patients and mRS 0–2 at 90 days in 35.8% of patients. In a multivariable model, the interaction between collateral status and recanalization was significant. Only patients with intermediate or good collaterals who recanalized showed a statistically significant association with good clinical outcome (rate ratio = 3.8; 95% CI, 1.2–12.1). Patients with good and intermediate collaterals who did not achieve recanalization and patients with poor collaterals, even if they achieved recanalization, did not do well.CONCLUSIONS:Patients with good or intermediate collaterals on CTA benefit from intra-arterial therapy, whereas patients with poor collaterals do not benefit from treatment.

Leptomeningeal collaterals are pre-existing anastomoses that connect a small number of distal-most arterioles within the crowns of the cerebral artery trees.^1,2 During an acute stroke, ischemic brain depends on blood flow from these collaterals to survive until the occluded artery is opened.^3–8 This collateral circulation is highly variable and potentially influences the rate at which an infarct grows.^4,8–10 Collateral status at baseline is an independent determinant of clinical outcome among patients with acute ischemic stroke.^3,5,7,8,11 Nonetheless, “effect modification” by collateral status measured noninvasively by use of CTA of the relationship between recanalization and clinical outcome has not been demonstrated before. This tool can be used to select patients for intra-arterial therapy (IAT) through demonstration of a differential clinical response to recanalization by collateral status.In this study, we first demonstrate the concept of validity of collateral status measured by use of CTA among patients presenting with acute ischemic stroke by correlating it with infarct volume on baseline MR DWI and infarct growth over 24 hours. We then demonstrate “effect modification” by collateral status of the relationship between recanalization and clinical outcome in patients with acute ischemic stroke undergoing IAT, thus justifying the use of baseline collateral status on CTA as a patient selection tool for IAT.     

Mechanical Thrombectomy with Stent Retrievers in Acute Ischemic Stroke

Mechanical thrombectomy (MTE) in patients with acute ischemic infarct caused by large-vessel occlusion is becoming used with increasing frequency in many stroke centers. With the introduction of stent retrievers, recanalization rates >80 % are reached by most operators. However, although the technical success rate of MTE has been increased, clinical results have not improved to the same degree. In this review, the indications for MTE, the technique, and the technical and clinical outcomes are discussed. Complications and predictors for good clinical outcome are described based on recent data from the literature.     

Safety of Intra-Arterial Tirofiban Administration in Ischemic Stroke Patients after Unsuccessful Mechanical Thrombectomy

Purpose

To assess the safety of low-dose intra-arterial (IA) tirofiban bolus after unsuccessful mechanical thrombectomy in patients with ischemic stroke due to large artery occlusion in anterior cerebral circulation.

The Curved MCA: Influence of Vessel Anatomy on Recanalization Results of Mechanical Thrombectomy after Acute Ischemic Stroke

BACKGROUND AND PURPOSE:Vessel anatomy is assumed to influence results of endovascular mechanical thrombectomy using stent retrievers. The purpose of this study was to analyze the influence of vessel curvature on recanalization results in patients with acute ischemic stroke caused by large-vessel occlusion.MATERIALS AND METHODS:In 159 patients (70 ± 12.8 years of age; 79 women) treated for acute ischemic stroke after carotid T and/or MCA occlusion by using stent retrievers, the following angles were measured in standard anteroposterior angiograms to describe vessel anatomy: first, between the terminal ICA segment and the most downward curved M1 segment conterminous to the proximal face of the thrombus (ICA/M1 angle); second, between the most proximal M1 segment and the segment immediately conterminous to the thrombus (M1/M1 angle); and additionally, in patients with distal M1/proximal M2 occlusion, the angle of the last curvature proximal of the thrombus (M1/M2 angle). Angles of patients with-versus-without successful recanalization were compared.RESULTS:Patients without successful recanalization (TICI 0–2a) showed significantly larger ICA/M1 angles (mean, 110°± 23.8° versus 69°± 28.7°, P < .001) and significantly larger M1/M1 angles (56°± 29.2° versus 29°± 26.6°, P = .001) than patients with successful recanalization (TICI 2b/3). In patients without successful recanalization after a distal M1 or proximal M2 occlusion, the M1/M2 angle was significantly larger than that in patients with successful recanalization (117° ± 34.3° versus 67° ± 29.5°, P = .006).CONCLUSIONS:This retrospective analysis showed that mechanical thrombectomy in the anterior circulation was significantly less often successful in patients with large vessel angles. Therefore, vessel curvature significantly influences the results of mechanical thrombectomy with stent retrievers for treatment of acute ischemic stroke. Further work is needed to understand the underlying causality.

Acute ischemic stroke is one of the leading causes of morbidity and mortality in industrialized countries.¹ While studies suggest that intravenous thrombolysis by using recombinant tissue plasminogen activator is barely effective in large-vessel occlusions,^2–4 recent studies have shown that endovascular mechanical thrombectomy (MT) by using second-generation devices, known as stent retrievers, is associated with high recanalization rates and substantially improved clinical outcome.^5–11 However, in approximately 10%–25% of the patients, a successful recanalization (TICI 2b/3) still cannot be achieved.^5–14 Only a couple of technical factors are understood that may determine the fate of these patients: First, histologic characteristics of thromboemboli may influence recanalization results.¹⁵ Second, thrombus length has been identified as a relevant factor.¹⁶ A recent study presented contradictory results, reporting that the recanalization success of MT was not significantly influenced by clot length.¹⁷ The exact thrombus location, being more proximal or distal within the MCA M1 segment, was demonstrated to be a significant determinant for clinical outcome, however not for recanalization success.¹⁸To date, no evidence of vessel anatomy influencing recanalization success exists, though experienced interventionalists report that MT with stent retrievers is less likely to be successful in patients with strongly curved vessels. Zhu et al¹⁹ reported that vessel branching and curvature are important determinants of recanalization success; however, their work was based on indirect MR imaging findings and focused on thrombectomy by using the Merci retriever (Concentric Medical, Mountain View, California), a first-generation device, which is now obsolete in most cases. In a previous study on MT by using the pREset thrombus retriever (Phenox, Bochum, Germany), we observed that successful recanalization was significantly less likely in patients with strongly curved MCAs.¹³ Consequently, in this study, we analyzed the influence of vessel anatomy, assessed in anteroposterior angiograms, on recanalization results in a larger sample size. The purpose of this study was also to assess information on prognostic cutoff values and the prevalence of unfavorable MCA anatomy.     

Susceptibility Vessel Sign on MRI Predicts Favorable Clinical Outcome in Patients with Anterior Circulation Acute Stroke Treated with Mechanical Thrombectomy

BACKGROUND AND PURPOSE:The susceptibility vessel sign on MR imaging has been reported to indicate acute occlusion from erythrocyte-rich thrombus. The purpose of this study was to evaluate the influence of the susceptibility vessel sign seen on MR imaging before treatment on the clinical outcome after mechanical thrombectomy for anterior circulation acute stroke.MATERIALS AND METHODS:We retrospectively included 73 consecutive patients who were treated for anterior circulation acute stroke by mechanical thrombectomy from December 2009 to September 2013. Each patient underwent MR imaging before mechanical thrombectomy. The presence (susceptibility vessel sign+) or absence of the susceptibility vessel sign (susceptibility vessel sign−) was recorded. Mechanical thrombectomy was performed either alone or in association with IV tPA according to the site and time after occlusion. Good functional outcome was defined by an mRS ≤2 at 3 months in susceptibility vessel sign+ and susceptibility vessel sign− groups. Patient clinical characteristics, initial NIHSS score and ASPECTS, site of occlusion, time between onset to groin puncture, TICI after mechanical thrombectomy, NIHSS score at day 1, and spontaneous hyperattenuation on CT at day 1 were also analyzed.RESULTS:Fifty-three patients with susceptibility vessel sign+ and 20 with susceptibility vessel sign− were included in our study. mRS ≤2 at 3 months occurred in 65% patients in the susceptibility vessel sign+ group and 26% in the susceptibility vessel sign− group (P = .004). On multivariate analysis, the susceptibility vessel sign was the only parameter before treatment that could predict mRS ≤2 at 3 months (OR, 8.7; 95% CI, 1.1–69.4; P = .04).CONCLUSIONS:Our study strongly suggests that the susceptibility vessel sign on MR imaging before treatment is predictive of favorable clinical outcome for patients presenting with anterior circulation acute stroke and treated with mechanical thrombectomy.

Stroke is a leading cause of adult disability. Approximately two-thirds of stroke survivors have long-term functional deficits that affect their quality of life.^1,2 Very recently, large prospective randomized trials have proved the clinical benefit of endovascular recanalization and, in particular, mechanical thrombectomy (MT) in patients with proximal anterior circulation acute stroke (ACAS).^3,4 In these studies, patients were included on the basis of the presence of a proximal artery occlusion without any characterization of thrombus subtypes (ie, fibrin-rich or erythrocyte-rich thrombus). A gradient recalled-echo (GRE) MR imaging sequence is commonly used to identify brain hemorrhage, and it may also differentiate fibrin-rich from erythrocyte-rich thrombus on the basis of the presence of a susceptibility vessel sign (SVS).^5,6There has been no study addressing the prognostic value of SVS in predicting good clinical recovery after MT, to our knowledge. The goal of our study was, therefore, to investigate whether the presence of the SVS is related to better clinical outcomes after MT with stent retrievers in patients presenting with ACAS.     

Safety and Efficacy of Baseline Antiplatelet Treatment in Patients Undergoing Mechanical Thrombectomy for Ischemic Stroke: Antiplatelets Before Mechanical Thrombectomy

PurposeTo investigate the safety and efficacy of baseline antiplatelet treatment in patients with acute ischemic stroke (AIS) undergoing mechanical thrombectomy (MT).Materials and MethodsBaseline use of antiplatelet medication before MT for (AIS) may provide benefit on reperfusion and clinical outcome but could also carry an increased risk of intracranial hemorrhage (ICH). All consecutive patients with AIS and treated with MT with and without intravenous thrombolysis (IVT) between January 2012 and December 2019 in all centers performing MT nationwide were reviewed. Data were prospectively collected in national registries (eg, SITS-TBY and RES-Q). Primary outcome was functional independence (modified Rankin Scale 0–2) at 3 months; secondary outcome was ICH.ResultsOf the 4,351 patients who underwent MT, 1,750 (40%) and 666 (15%) were excluded owing to missing data from the functional independence and ICH outcome cohorts, respectively. In the functional independence cohort (n = 2,601), 771 (30%) patients received antiplatelets before MT. Favorable outcome did not differ in any antiplatelet, aspirin, and clopidogrel groups when compared with that in the no-antiplatelet group: odds ratio (OR), 1.00 (95% CI, 0.84–1.20); OR, 1.05 (95% CI, 0.86–1.27); and OR, 0.88 (95% CI, 0.55–1.41), respectively. In the ICH cohort (n = 3,685), 1095 (30%) patients received antiplatelets before MT. The rates of ICH did not increase in any treatment options (any antiplatelet, aspirin, clopidogrel, and dual antiplatelet groups) when compared with those in the no-antiplatelet group: OR, 1.03 (95% CI, 0.87–1.21); OR, 0.99 (95% CI, 0.83–1.18); OR, 1.10 (95% CI, 0.82–1.47); and OR, 1.43 (95% CI, 0.87–2.33), respectively.ConclusionsAntiplatelet monotherapy before MT did not improve functional independence or increase the risk of ICH.     

关急性缺血性脑卒中患者阻塞部位与功能恢复相

目的：探讨重组组织型纤溶酶原激活剂（ rt－PA）治疗急性缺血性脑卒中后临床症状轻度改善时间是否可以预测1年后功能恢复情况。方法186例急性大脑前循环梗塞患者,且发病3 h内接受rt－PA治疗,作为研究对象。患者根据临床症状轻度改善时间可以分为：早期见效者（ ER）,即rt－PA治疗2 h内NIHSS评分改善≥4或其中一项NIHSS评分为0;晚期见效者（ LR）, rt－PA治疗2 h－24 h内,NIHSS评分改善≥4或其中一项NIHSS评分为0;无效果者（ NR）。此外,根据患者动脉阻塞部位分为：颈内动脉和大脑中动脉M1段近端（ P组）;大脑中动脉M1、M2段远端（ D组）。结果 P组包括96例（52％）患者, D组包括90例（48％）患者。76例（41％）患者属于ER,40例（22％）患者是LR,70例（38％）患者为NR。多元线性回归分析显示,P组（OR：3.04;95％CI：1.18－10.45; P＝0.031）和NR （OR：4.14;95％ CI,1.29－14.27; P＝0.014）是1年后临床功能恢复较差的独立预测因素。 ER （53％, P＝0.01）和LR （55％, P＝0.01）患者临床功能恢复比例高于NR （23％）患者,ER和LR临床功能恢复率无显著统计学意义。结论早期轻度临床症状改善不能预测脑梗塞后1年功能恢复,但是阻塞部位是rt－PA治疗后功能恢复的有效预测因素。     

Multiphasic Perfusion CT in Acute Middle Cerebral Artery Ischemic Stroke: Prediction of Final Infarct Volume and Correlation with Clinical Outcome

Objective

To assess the utility of multiphasic perfusion CT in the prediction of final infarct volume, and the relationship between lesion volume revealed by CT imaging and clinical outcome in acute ischemic stroke patients who have not undergone thrombolytic therapy.

Materials and Methods

Thirty-five patients underwent multiphasic perfusion CT within six hours of stroke onset. After baseline unenhanced helical CT scanning, contrast-enhanced CT scans were obtained 20, 34, 48, and 62 secs after the injection of 90 mL contrast medium at a rate of 3 mL/sec. CT peak and total perfusion maps were obtained from serial CT images, and the initial lesion volumes revealed by CT were compared with final infarct volumes and clinical scores.

Results

Overall, the lesion volumes seen on CT peak perfusion maps correlated most strongly with final infarct volumes (R²=0.819, p<0.001, slope of regression line=1.016), but individual data showed that they were less than final infarct volume in 31.4% of patients. In those who showed early clinical improvement (n=6), final infarct volume tended to be overestimated by CT peak perfusion mapping and only on total perfusion maps was there significant correlation between lesion volume and final infarct volume (R²=0.854, p=0.008). The lesion volumes depicted by CT maps showed moderate correlation with baseline clinical scores and clinical outcomes (R=0.445-0.706, p≤0.007).

Conclusion

CT peak perfusion maps demonstrate strong correlation between lesion volume and final infarct volume, and accurately predict final infarct volume in about two-thirds of the 35 patients. The lesion volume seen on CT maps shows moderate correlation with clinical outcome.     

Mechanical Thrombectomy of Distal Occlusions in the Anterior Cerebral Artery: Recanalization Rates,Periprocedural Complications,and Clinical Outcome

BACKGROUND AND PURPOSE:Patients with acute ischemic stroke in the anterior circulation are at risk for either primary or, following mechanical thrombectomy, secondary occlusion of the anterior cerebral artery. Because previous studies had only a limited informative value, we report our data concerning the frequency and location of distal anterior cerebral artery occlusions, recanalization rates, periprocedural complications, and clinical outcome.MATERIALS AND METHODS:We performed a retrospective analysis of prospectively collected data of patients with acute ischemic stroke undergoing mechanical thrombectomy in the anterior circulation between June 2010 and April 2015.RESULTS:Of 368 patients included in this analysis, we identified 30 (8.1%) with either primary (n = 17, 4.6%) or secondary (n = 13, 3.5%) embolic occlusion of the distal anterior cerebral artery. The recanalization rate after placement of a stent retriever was 88%. Periprocedural complications were rare and included vasospasms (n = 3, 10%) and dissection (n = 1, 3.3%). However, 16 (53.5%) patients sustained an (at least partial) infarction of the anterior cerebral artery territory. Ninety days after the ictus, clinical outcome according to the modified Rankin Scale score was the following: 0–2, n = 11 (36.6%); 3–4, n = 9 (30%); 5–6, n = 10 (33.3%).CONCLUSIONS:Occlusions of the distal anterior cerebral artery affect approximately 8% of patients with acute ischemic stroke in the anterior circulation receiving mechanical thrombectomy. Despite a high recanalization rate and a low complication rate, subsequent (partial) infarction in the anterior cerebral artery territory occurs in approximately half of patients. Fortunately, clinical outcome appears not to be predominately unfavorable.

Mechanical thrombectomy (MT) is an effective treatment in acute ischemic stroke secondary to a large-vessel occlusion.^1–4 Patients with acute ischemic stroke secondary to an occlusion of the internal carotid artery–T, middle cerebral artery trunk (M1), or MCA secondary division (M2) have relatively high rates of revascularization and favorable clinical outcomes after MT.^5,6 Unfortunately, for patients with ICA-T occlusions and MCA occlusions, there is a risk of approximately 8.6%–11.4% for secondary emboli into the anterior cerebral artery (ACA), especially the distal branches such as the pericallosal artery, during MT.^2,7,8 Although various technical possibilities, such as proximal flow control or combined aspiration, have been recommended to reduce the risk of secondary emboli^9–13, occlusions of the distal ACA occur.Regardless of the cause of the occlusion (primary occlusion or secondary emboli during MT), cerebral infarctions in the ACA territory may cause relevant clinical deficits by affecting the primary or supplementary motor areas.¹⁴ In a previous, relatively small patient cohort (n = 6), treatment of secondary ACA occlusions was technically successful in 80% of the cases and uneventful in all instances.⁷We present data on the frequency and location of distal ACA occlusions, recanalization rates, periprocedural complications, and clinical outcome.     

Procedural Predictors of Outcome in Patients Undergoing Endovascular Therapy for Acute Ischemic Stroke

Purpose

To identify factors impacting outcome in patients undergoing interventions for acute ischemic stroke (AIS).

Materials and Methods

This was a retrospective analysis of patients undergoing endovascular therapy for AIS secondary during a 30?month period. Outcome was based on modified Rankin score at 3- to 6-month follow-up. Recanalization was defined as Thrombolysis in myocardial infarction score 2 to 3. Collaterals were graded based on pial circulation from the anterior cerebral artery either from an ipsilateral injection in cases of middle cerebral artery (MCA) occlusion or contralateral injection for internal carotid artery terminus (ICA) occlusion as follows: no collaterals (grade 0), some collaterals with retrograde opacification of the distal MCA territory (grade 1), and good collaterals with filling of the proximal MCA (M2) branches or retrograde opacification up to the occlusion site (grade 2). Occlusion site was divided into group 1 (ICA), group 2 (MCA with or without contiguous M2 involvement), and group 3 (isolated M2 or M3 branch occlusion).

Results

A total of 89 patients were studied. Median age and National Institutes of health stroke scale (NIHSS) score was 71 and 15?years, respectively. Favorable outcome was seen in 49.4% of patients and mortality in 25.8% of patients. Younger age (P?=?0.006), lower baseline NIHSS score (P?=?0.001), successful recanalization (P?<?0.0001), collateral support (P?=?0.0008), distal occlusion (P?=?0.001), and shorter procedure duration (P?=?0.01) were associated with a favorable outcome. Factors affecting successful recanalization included younger age (P?=?0.01), lower baseline NIHSS score (P?=?0.05), collateral support (P?=?0.01), and shorter procedure duration (P?=?0.03). An ICA terminus occlusion (P?<?0.0001), lack of collaterals (P?=?0.0003), and unsuccessful recanalization (P?=?0.005) were significantly associated with mortality.

Conclusion

Angiographic findings and preprocedure variables can help prognosticate procedure outcomes in patients undergoing endovascular therapy for AIS.     

Association of Aortic Arch Calcification with Acute Ischemic Stroke Subtypes and Endovascular Thrombectomy Outcomes

PurposeTo analyze the aortic arch calcification (AAC) on computed tomography (CT) scans, with the goal of predicting the subtypes of patients with ischemic stroke and endovascular thrombectomy (EVT) outcomes.Materials and MethodsAutomated analysis was used to quantify AAC on CT scans. From January 2020 to March 2021, 119 patients diagnosed with ischemic stroke were analyzed, and the feasibility of EVT was assessed; 43 underwent the procedure.ResultsAAC was present in 117 (98.3%) of 119 patients. There was a significant difference (P <.001) in AAC severity among all patients with ischemic stroke according to the Trial of ORG 10172 in Acute Stroke Treatment classification. In patients who underwent EVT, AAC severity was significantly related to the thrombolysis in cerebral infarction grade, thrombectomy procedure time, and modified Rankin scale at discharge (P =.002, P =.035 and P =.015, respectively). Multivariate logistic regression analysis also showed that severe AAC (volume, ≥1,000 mm³) (adjusted odds ratio [OR], 12.1; adjusted 95% confidence interval [CI]), 2.1–36.4; P =.001) and intracranial atherosclerotic disease (adjusted OR, 9.5; adjusted 95% CI, 2.3–33.7; P =.001) were both independently associated with poor thrombolysis reperfusion rate.ConclusionsA high proportion of patients with ischemic stroke have AAC, the severity of which is a potential imaging marker of ischemic stroke subtypes and the outcome of EVT.     

Comparison of Imaging Selection Criteria for Intra-Arterial Thrombectomy in Acute Ischemic Stroke with Advanced CT

Objectives

To compare two selection criteria (noncontrast CT [NCCT] with multi-phase CT Angiography [MPCTA] and CT perfusion [CTP]) for the determination of eligibility for thrombectomy.

Methods

We retrospectively enrolled 71 patients who underwent head NCCT, 9.6-cm CTP, and craniocervical single-phase CTA (SPCTA) within 6 hours of onset. The simulated MPCTA was reconstructed from 1-mm CTP images for assessment of collateral circulation. Infarct core (relative CBF <?30 %) and penumbra (Tmax > 6 seconds) volumes were measured. The infarct core?<?70 mL with a mismatch ratio?>?1.2 (CTP-A), infarct core?≤?40 mL with a mismatch ratio?>?1.8 (CTP-B), and ASPECTS?>?5 with good collaterals (50 %?≥?MCA territory) were used to determine eligibility for thrombectomy. SPCTA was compared with the simulated MPCTA for assessment of collaterals.

Results

CTP-B determined that 11 patients were ineligible for thrombectomy, of which three were eligible by NCCT with MPCTA and 6 by CTP-A. CTP-A and CTP-B showed discrepancy in determining eligibility for thrombectomy between NCCT with MPCTA in three patients each, rendering no significant statistical difference (P?>?0.05). The number of patients with poor collaterals was significantly higher on SPCTA than MPCTA (n?=?22 and 6 respectively; P?<?0.0001).

Conclusion

The two imaging selection criteria (NCCT with MPCTA and CTP) were statistically comparable for determining eligibility for thrombectomy.

Key Points

? Early mechanical thrombectomy improves clinical outcomes. ? Noncontrast CT–multi-phase CTA is used for determining eligibility for thrombectomy. ? CTP can help to select patients who are eligible for thrombectomy. ? Noncontrast CT–multi-phase CTA and CTP are comparable for patient selection. ? Multi-phase CTA is more accurate than single-phase CTA for assessment of collaterals.

     

Predictors of Reperfusion in Patients with Acute Ischemic Stroke

BACKGROUND AND PURPOSE:Ischemic stroke studies emphasize a difference between reperfusion and recanalization, but predictors of reperfusion have not been elucidated. The aim of this study was to evaluate the relationship between reperfusion and recanalization and identify predictors of reperfusion.MATERIALS AND METHODS:From the Dutch Acute Stroke Study, 178 patients were selected with an MCA territory deficit on admission CTP and day 3 follow-up CTP and CTA. Reperfusion was evaluated on CTP, and recanalization on CTA, follow-up imaging. Reperfusion percentages were calculated in patients with and without recanalization. Patient admission and treatment characteristics and admission CT imaging parameters were collected. Their association with complete reperfusion was analyzed by using univariate and multivariate logistic regression.RESULTS:Sixty percent of patients with complete recanalization showed complete reperfusion (relative risk, 2.60; 95% CI, 1.63–4.13). Approximately one-third of patients showed some discrepancy between recanalization and reperfusion status. Lower NIHSS score (OR, 1.06; 95% CI, 1.01–1.11), smaller infarct core size (OR, 3.11; 95% CI, 1.46–6.66; and OR, 2.40; 95% CI, 1.14–5.02), smaller total ischemic area (OR, 4.20; 95% CI, 1.91–9.22; and OR, 2.35; 95% CI, 1.12–4.91), lower clot burden (OR, 1.35; 95% CI, 1.14–1.58), distal thrombus location (OR, 3.02; 95% CI, 1.76–5.20), and good collateral score (OR, 2.84; 95% CI, 1.34–6.02) significantly increased the odds of complete reperfusion. In multivariate analysis, only total ischemic area (OR, 6.12; 95% CI, 2.69–13.93; and OR, 1.91; 95% CI, 0.91–4.02) was an independent predictor of complete reperfusion.CONCLUSIONS:Recanalization and reperfusion are strongly associated but not always equivalent in ischemic stroke. A smaller total ischemic area is the only independent predictor of complete reperfusion.

Patients with acute ischemic stroke presenting within 4.5 hours are treated with IV-rtPA to dissolve the thrombus and achieve revascularization.¹ A recent consensus meeting on stroke imaging research (Acute Stroke Imaging Research Roadmap II) suggests that revascularization is a combination of 3 different mechanisms: 1) recanalization, referring to arterial patency; 2) reperfusion, which refers to antegrade microvascular perfusion; and 3) collateralization, which refers to microvascular perfusion via pial arteries or other anastomotic arterial channels that bypass the primary site of vessel occlusion.² Recanalization, reperfusion, and collateralization can be evaluated by CTA and CTP, which are frequently used in dedicated stroke imaging protocols. An important reason to look at the revascularization mechanisms separately is the concept that recanalization of an arterial occlusion, as visualized on CTA, does not necessarily lead to complete reperfusion and improved clinical outcome.^3,4 Furthermore, reperfusion can also occur without afferent vessel recanalization through collateralization of the ischemic area by collateral flow.^5,6Many previous studies, including those investigating intra-arterial therapy, consider recanalization to be synonymous with reperfusion.^7–10 Other articles suggest that this assumption is not justified and found reperfusion to be a better predictor of follow-up infarct volume and clinical outcome than recanalization.^{5,8,9,11–15}Although recanalization correlates well with improved reperfusion rates, it is unclear which other clinical and imaging factors influence reperfusion.^5,6,11,12,16 Knowing which factors, available before treatment decisions, predict complete reperfusion could aid in decision-making. Treatment with IV-rtPA, good collateral scores and lesion geography (location of the infarct relative to penumbra), and structure (solitary or multiple infarct areas) have been related to reperfusion status assessed with CT or MR imaging.^5,15,17–19The aim of this study was to evaluate the relationship between reperfusion and recanalization and to investigate which clinical and CT imaging parameters, available on admission, can help predict complete reperfusion in patients with acute ischemic stroke.     

Fast Stent Retrieval during Mechanical Thrombectomy Improves Recanalization in Patients with the Negative Susceptibility Vessel Sign

BACKGROUND AND PURPOSE:In acute ischemic stroke, the negative susceptibility vessel sign on T2*-weighted images traditionally highlights fibrin-rich clots, which are particularly challenging to remove. In vitro, fast stent retrieval improves fibrin-rich clot extraction. We aimed to evaluate whether the speed of stent retrieval influences the recanalization and clinical outcome of patients presenting with the negative susceptibility vessel sign.MATERIALS AND METHODS:Patients were identified from a registry of patients with ischemic stroke receiving mechanical thrombectomy between January 2016 and January 2020. Inclusion criteria were the following: 1) acute ischemic stroke caused by an isolated occlusion of the anterior circulation involving the MCA (Internal Carotid Artery-L, M1, M2) within 8 hours of symptom onset; 2) a negative susceptibility vessel sign on prethrombectomy T2*-weighted images; and 3) treatment with a combined technique (stent retriever + contact aspiration). Patients were dichotomized according to retrieval speed (fast versus slow). The primary outcome was the first-pass recanalization rate.RESULTS:Of 68 patients who met inclusion criteria, 31 (45.6%) were treated with fast retrieval. Patients receiving a fast retrieval had greater odds of first-pass complete (relative risk and 95% confidence interval [RR 95% CI], 4.30 [1.80–10.24]), near-complete (RR 95% CI, 3.24 [1.57–6.68]), and successful (RR 95% CI, 2.60 [1.53–4.43]) recanalization as well as greater odds of final complete (RR 95% CI, 4.18 [1.93–9.04]), near-complete (RR 95% CI, 2.75 [1.55–4.85]), and successful (RR 95% CI, 1.52 [1.14–2.03]) recanalization. No significant statistical differences in procedure-related serious adverse events, distal embolization, or symptomatic intracranial hemorrhage were reported. No differences were noted in terms of functional independence (RR 95% CI, 1.01 [0.53–1.93]) and all-cause mortality (RR 95% CI, 0.90 [0.35–2.30]) at 90 days.CONCLUSIONS:A fast stent retrieval during mechanical thrombectomy is safe and improves the retrieval of clots with the negative susceptibility vessel sign.

In acute ischemic stroke, the susceptibility vessel sign (SVS) on T2*-weighted sequences is thought to highlight the red blood cells in the clot.^1-3 Histopathologic correlations of retrieved thrombi with MR imaging features showed that clots not visible on T2*-weighted images (negative SVS) contained a high proportion of fibrin,^1,2 which makes them particularly firm and sticky,^4,5 and thus very challenging to remove mechanically.^5-7 Approximately 20% of patients receiving bridging therapy cannot achieve recanalization,^7,8 possibly due, in part, to how difficult it is to tailor the retrieval technique to clot properties.⁹ Recent in vitro experiments have shown that fast retrieval of the clot using a combined technique (contact aspiration + stent retriever) can improve recanalization, especially with fibrin-rich clots.¹⁰ Currently, device manufacturers’ instructions advise operators to withdraw stent retrievers slowly to avoid potential artery dissection or rupture. Yet, the effect of retrieval speed on mechanical thrombectomy success in vivo has yet to be explored. A fast retrieval may mobilize the clot suddenly, enhance clot wedging, and minimize loss of apposition during retrieval.¹⁰ The present study aimed to evaluate whether stent-retrieval speed influences recanalization rates and clinical outcome in patients presenting with negative SVS clots.     

The Outcome and Efficacy of Recanalization in Patients with Acute Internal Carotid Artery Occlusion

BACKGROUND AND PURPOSE:Acute occlusion of the ICA is often associated with poor outcomes and severe neurologic deficits. This study was conducted to evaluate outcome of the occluded ICA and efficacy of recanalization under protective flow arrest.MATERIALS AND METHODS:Fifty consecutive patients who underwent endovascular treatment for acute ICA occlusion were identified from the prospectively collected data base. We assessed NIHSS_o, occlusion type (cardioembolism vs atherosclerosis), occlusion level (supraclinoid-terminal, petrocavernous, or bulb-cervical), recanalization degree (TICI), and efficacy of recanalization (protective flow arrest vs nonprotection) leading to better outcome.RESULTS:Successful recanalization (TICI ≥ 2) was obtained in 90% of patients and good recovery (mRS ≤ 2) in 60% of patients. Good outcome was related to National Institutes of Health Stroke Scale score on admission (P < .001), TICI (P < .007), occlusion type (P = .022), and occlusion level (P = .038). Poor initial patient status, less recanalization, cardioembolism, and supraclinoid-terminal occlusion were associated with poor prognosis. Application of protective flow arrest led to better outcome in the distal ICA segment than in the bulb-cervical segment.CONCLUSIONS:In addition to the initial patient status and successful recanalization, the occlusion level or type of the occluded ICA could affect clinical outcome. In this study, treatment benefits of protective flow arrest were accentuated in patients with ICA occlusion above the bulb-cervical segment.

Acute occlusion of the ICA is often associated with poor outcomes and severe neurologic deficits.^1,2 Acute ICA occlusions are more resistant than MCA occlusions to administration of intravenous tPA.^3,4 In the Trial of Org 10172 in Acute Stroke Treatment (TOAST), 10% of patients were diagnosed with ICA occlusion, which resulted in neurologic disability in 40% and mortality in 20% of patients.⁵Intra-arterial mechanical thrombectomy has been increasingly used in the management of acute ischemic stroke with the recent introduction of stent retrievers (nondetachable microcatheter-based stentlike devices).^6–9 Despite anecdotal endovascular attempts, an effective management approach has not been well established for patients with acute ICA occlusion that is not applicable to intravenous and/or intra-arterial thrombolysis.^10–13 The aims of the present study were to investigate the outcome and factors associated with recanalization therapy in acute occlusion of the ICA and to assess the efficacy of proximal flow arrest.