Proximal M1 Research Articles

Endovascular treatment for proximal middle cerebral artery occlusion due to underlying intracranial atherosclerotic disease: A retrospective single-center case series

ObjectiveTo compare treatment outcomes between patients who received a front-line stent-retriever thrombectomy (SRT) or first stenting without retrieval (FRESH) for treating proximal M1 occlusion due to underlying intracranial atherosclerotic disease (ICAD). MethodsWe retrospectively reviewed consecutive acute ischemic stroke (AIS) patients with intracranial large vessel occlusion (LVO) in the anterior circulation who underwent endovascular treatment (EVT) between January 2017 and August 2021 at Yeungnam University Medical Center. LVO in the anterior circulation was classified according to etiology as follows: Embolic group and ICAD group. Occlusion of the proximal M1 due to ICAD were enrolled in this study. The ICAD group was divided into SRT and FRESH groups according to the treatment method. ResultsAmong the 72 patients in the ICAD group, 55 patients had occlusion of the M1, and 27 had occlusion of the proximal M1 (27/55, 49.1 %). Among the 27 patients, 11 (40.7 %) underwent SRT and 16 (59.3 %) underwent FRESH. The puncture-to-recanalization time was significantly shorter in the FRESH group (28 min vs. 52 min, p = 0.023). Symptomatic ICH tended to occur more frequently in the SRT group than in the FRESH group (27.3 % vs. 0.0 %, p=0.056). There was a nonsignificant trend towards a good functional outcome in the FRESH group compared to the SRT group (81.3 % vs. 45.5 %, p=0.097). ConclusionIn the FRESH group, the puncture-to-recanalization time was significantly shorter, symptomatic ICH tended to occur less frequently, and good functional outcomes were more common.

Endovascular thrombectomy for acute ischemic stroke with a large infarct area: An updated systematic review and meta-analysis of randomized controlled trials

BackgroundSince the efficacy and safety of endovascular thrombectomy (EVT) in patients with acute ischemic stroke with a large infarct area is still inconclusive, we sought to compare functional and neurological outcomes with the use of endovascular thrombectomy versus medical care alone. MethodsWe searched MEDLINE (via PubMed), Embase, Cochrane Library, ClinicalTrials.gov, and the International Clinical Trials Registry Platform (ICTRP) to retrieve all the relevant randomized controlled trials (RCTs) on this topic. Review manager (RevMan) was used to perform meta-analyses using a random-effect model. Dichotomous outcomes were pooled using risk ratios (RR) with 95% confidence intervals (CIs). ResultsOur meta-analysis included 6 RCTs with a total of 1665 patients. Most studies included patients with an ASPECTS score of 3-5. Our results demonstrate that endovascular thrombectomy significantly increased the rates of functional independence (mRS ≤ 2) (RR, 2.49; 95% CI, 1.89-3.29) and moderate neurological outcome (mRS ≤ 3) (RR, 1.90; 95% CI, 1.50-2.40) at 90 days. The benefit of EVT for these outcomes remained the same at 1-year follow-up. Endovascular thrombectomy was associated with increased rates of early neurological improvement (RR, 2.22; 95% CI, 1.53-3.22), excellent neurological recovery (mRS ≤ 1) (RR, 1.75; 95% CI, 1.02-3.03), and decreased rate of poor neurological recovery (mRS 4-6) (RR, 0.81; 95% CI, 0.76-0.86). No significant difference was found between the two groups regarding all-cause mortality (RR, 0.86; 95% CI, 0.72-1.02), decompressive craniectomy (RR, 1.32; 95% CI, 0.89-1.94), and the incidence of serious adverse effects (RR, 1.39; 95% CI, 0.83-2.32) between the two groups. Endovascular thrombectomy significantly increased the rates of any intracranial hemorrhage (RR, 1.94; 95% CI, 1.48-2.53) and symptomatic intracranial hemorrhage (RR, 1.73; 95% CI, 1.11-2.69). ConclusionEndovascular thrombectomy (EVT) significantly improves neurological and functional outcomes in patients who present within 6 hours of stroke onset with ICA and proximal M1 occlusions, and ASPECTS scores ranging from 3 to 5, compared to medical therapy alone, with an increased risk of symptomatic intracranial hemorrhage.

Tenecteplase Versus Alteplase in Medium Vessel Occlusion Ischemic Stroke: A Secondary Analysis of the Alteplase Compared to Tenecteplase Randomized Trial.

The safety and efficacy of tenecteplase in patients with ischemic stroke due to medium vessel occlusion (MeVO) are not well studied. We aimed to compare tenecteplase with alteplase in stroke due to MeVO. Patients with baseline M2-middle cerebral artery (MCA), M3/M4-MCA, P2/P3/P4-posterior cerebral artery (PCA), A2/A3/A4-anterior cerebral artery (ACA) occlusions from the Alteplase Compared to Tenecteplase (AcT) trial were included. Primary outcome was the proportion of 90-day modified Rankin Scale (mRS) 0-1. Secondary outcomes were 90-day mRS 0-2, ordinal mRS, mortality, quality of life measures (EuroQol 5-Dimension 5-Level, EuroQol visual analog scale), and symptomatic intracerebral hemorrhage (sICH). Initial and final successful reperfusion were reported in patients undergoing endovascular thrombectomy (EVT). Among 1,558 patients with available baseline computed tomography angiography; 455 (29.2%) had MeVO of which 27.5% (125/455) were proximal M2; 16.3% (74/455) were distal M2; 35.2% (160/455) were M3/M4; 7.5% (34/455) were A2/A3/A4; and 13.6% (62/455) were P2/P3/P4 occlusions. EVT was performed in 87/455 (19.1%) patients. mRS 0-1 at 90 days was achieved in 37.9% in the tenecteplase versus 34.7% in the alteplase group (adjusted risk ratio [aRR] 1.07; 95% confidence interval [CI] 0.91-1.25). Rates of 90-day mRS 0-2, sICH, and mortality were similar in both groups. No statistical difference was noted in initial successful reperfusion rates (13.0% vs. 7.5%) among the 87 patients who underwent endovascular thrombectomy. However, final successful reperfusion was higher in the tenecteplase group (71.7% vs. 60.0%, aRR 1.29, 95% CI 1.04-1.61). Intravenous tenecteplase had comparable safety, functional outcomes and quality of life compared to intravenous alteplase among patients with MeVO. Among those treated with EVT, tenecteplase was associated with higher successful reperfusion rates than alteplase.

Lower admission stroke severity is associated with good collateral status in distal medium vessel occlusion stroke.

Distal medium vessel occlusions (DMVOs) are a significant contributor to acute ischemic stroke (AIS), with collateral status (CS) playing a pivotal role in modulating ischemic damage progression. We aimed to explore baseline characteristics associated with CS in AIS-DMVO. This retrospective analysis of a prospectively collected database enrolled 130 AIS-DMVO patients from two comprehensive stroke centers. Baseline characteristics, including patient demographics, admission National Institutes of Health Stroke Scale (NIHSS) score, admission Los Angeles Motor Scale (LAMS) score, and co-morbidities, including hypertension, hyperlipidemia, diabetes, coronary artery disease, atrial fibrillation, and history of transient ischemic attack or stroke, were collected. The analysis was dichotomized to good CS, reflected by hypoperfusion index ratio (HIR) <.3, versus poor CS, reflected by HIR ≥.3. Good CS was observed in 34% of the patients. As to the occluded location, 43.8% occurred in proximal M2, 16.9% in mid M2, 35.4% in more distal middle cerebral artery, and 3.8% in distal anterior cerebral artery. In multivariate logistic analysis, a lower NIHSS score and a lower LAMS score were both independently associated with a good CS (odds ratio [OR]: 0.88, 95% confidence interval [CI]: 0.82-0.95, p<.001 and OR: 0.77, 95% CI: 0.62-0.96, p=.018, respectively). Patients with poor CS were more likely to manifest as moderate to severe stroke (29.1% vs. 4.5%, p<.001), while patients with good CS had a significantly higher chance of having a minor stroke clinically (40.9% vs. 12.8%, p<.001). CS remains an important determinant in the severity of AIS-DMVO. Collateral enhancement strategies may be a worthwhile pursuit in AIS-DMVO patients with more severe initial stroke presentation, which can be swiftly identified by the concise LAMS and serves as a proxy for underlying poor CS.

Vascular syndrome predicts the development and course of epilepsy after perinatal stroke.

Epilepsy develops in one third of the patients after perinatal stroke. It is still unclear which vascular syndrome of ischemic stroke carries higher risk of epilepsy. The aim of the current study was to evaluate the risk of epilepsy according to the vascular syndrome of perinatal stroke. The study included 39 children with perinatal arterial ischemic stroke (13 with anterior or posterior trunk of the distal middle cerebral artery occlusion, 23 with proximal or distal M1 middle cerebral artery occlusion and three with lenticulostriate arteria infarction), and 44 children with presumed perinatal venous infarction. Magnetic resonance imaging obtained at the chronic stage was used to evaluate the vascular syndrome of stroke. The median follow-up time was 15.1 years (95% CI: 12.4-16.5 years), epilepsy developed in 19/83 (22.9%) patients. The cumulative probability to be without epilepsy at 15 years was 75.4% (95% CI: 65.8-86.4). The probability of having epilepsy was higher in the group of proximal or distal M1 artery occlusion compared to patients with periventricular venous infarction (HR 7.2, 95% CI: 2.5-26, p = .0007). Patients with periventricular venous infarction had significantly more often status epilepticus or spike-wave activation in sleep ≥85% of it compared to patients with anterior or posterior trunk of the distal middle cerebral artery occlusion (OR = 81; 95% CI: 1.3-5046, p = .029). The emphasis of this study is placed on classifying the vascular syndrome of perinatal stroke and on the targeted follow-up of patients for epilepsy until young adulthood. The risk for having epilepsy after perinatal stroke is the highest in children with proximal or distal M1 middle cerebral artery occlusion. Patients with periventricular venous infarction have a more severe course of epilepsy.

A deep learning method to identify and localize large-vessel occlusions from cerebral digital subtraction angiography.

An essential step during endovascular thrombectomy is identifying the occluded arterial vessel on a cerebral digital subtraction angiogram (DSA). We developed an algorithm that can detect and localize the position of occlusions in cerebral DSA. We retrospectively collected cerebral DSAs from a single institution between 2018 and 2020 from 188 patients, 86 of whom suffered occlusions of the M1 and proximal M2 segments. We trained an ensemble of deep-learning models on fewer than 60 large-vessel occlusion (LVO)-positive patients. We evaluated the model on an independent test set and evaluated the truth of its predicted localizations using Intersection over Union and expert review. On an independent test set of 166 cerebral DSA frames with an LVO prevalence of 0.19, the model achieved a specificity of 0.95 (95% confidence interval [CI]: 0.90, 0.99), a precision of 0.7450 (95% CI: 0.64,0.88), and a sensitivity of 0.76 (95% CI: 0.66, 0.91). The model correctly localized the LVO in at least one frame in 13 of the 14 LVO-positive patients in the test set. The model achieved a precision of 0.67 (95% CI: 0.52, 0.79), recall of 0.69 (95% CI: 0.46, 0.81), and a mean average precision of 0.75 (95% CI: 0.56, 0.91). This work demonstrates that a deep learning strategy using a limited dataset can generate effective representations used to identify LVOs. Generating an expanded and more complete dataset of LVOs with obstructed LVOs is likely the best way to improve the model's ability to localize LVOs.

Arterial Tortuosity Is a Potent Determinant of Safety in Endovascular Therapy for Acute Ischemic Stroke

Background Subarachnoid hemorrhage (SAH) associated with vessel injury during endovascular therapy for acute ischemic stroke is a known complication. Arterial anatomy may predispose to increased risk of SAH and technical safety, yet factors such as clot location, arterial size, and tortuosity have not been explored. We examined these anatomic factors with respect to SAH during thrombectomy. Methods Arterial anatomy at the site of occlusion and mechanical thrombectomy during device deployment was detailed by the STRATIS (Systematic Evaluation of Patients Treated With Neurothrombectomy Devices for Acute Ischemic Stroke) core laboratory. Luminal diameters, arterial branching, and segmental tortuosity were measured. Arterial tortuosity was quantified using the distance factor metric. Statistical analyses included descriptive variables of arterial anatomy, with univariable and multivariable modeling to predict SAH. Results Arterial tortuosity in each segment from the proximal cerebral arteries to the site of occlusion was quantified in 790 subjects treated with mechanical thrombectomy in STRATIS. Cumulative arterial tortuosity to the site of vessel occlusion was greater in distal lesions. SAH was clearly linked with more distal thrombectomy ( P = 0.02), occurring in 19.0% of distal M2, 16.7% of M3, 7.3% of distal M1, 5.8% of proximal M2, 2.4% of distal internal carotid artery, and 2.1% of proximal M1. In multivariable analysis after adjusting for arterial diameter at the site of occlusion, arterial tortuosity was a significant predictor of SAH (upper tertile versus 1: odds ratio, 3.08 [95% CI, 1.04–9.09]; P = 0.04), while arterial diameter was unrelated to SAH ( P = 0.30) when accounting for tortuosity. Conclusion This novel analysis of arterial tortuosity and angiographic anatomy during mechanical thrombectomy establishes tortuosity as a determinant of SAH, providing insight for future techniques and innovative device designs.

Association between occlusion location, net water uptake and ischemic lesion growth in large vessel anterior circulation strokes

Ischemic lesion net water uptake (NWU) represents a quantitative imaging biomarker for cerebral edema in acute ischemic stroke. Data on NWU for distinct occlusion locations remain scarce, but might help to improve the prognostic value of NWU. In this retrospective multicenter cohort study, we compared NWU between patients with proximal large vessel occlusion (pLVO; ICA or proximal M1) and distal large vessel occlusion (dLVO; distal M1 or M2). NWU was quantified by densitometric measurements of the early ischemic region. Arterial collateral status was assessed using the Maas scale. Regression analysis was used to investigate the relationship between occlusion location, NWU and ischemic lesion growth. A total of 685 patients met inclusion criteria. Early ischemic lesion NWU was higher in patients with pLVO compared with dLVO (7.7% vs 3.9%, P < .001). The relationship between occlusion location and NWU was partially mediated by arterial collateral status. NWU was associated with absolute ischemic lesion growth between admission and follow-up imaging (β estimate, 5.50, 95% CI, 3.81–7.19, P < .001). This study establishes a framework for the relationship between occlusion location, arterial collateral status, early ischemic lesion NWU and ischemic lesion growth. Future prognostic thresholds for NWU might be optimized by adjusting for the occlusion location.

Neurological Improvement by One-Thirds Is Associated With Early Recanalization in Stroke With Large Vessel Occlusion.

A proportion of large vessel occlusion strokes demonstrate early recanalization, obviating the initial intention to proceed to endovascular thrombectomy. Neurological improvement is a possible surrogate marker for reperfusion. We aimed to determine the optimal threshold of neurological improvement, as defined by the National Institutes of Health Stroke Scale (NIHSS), which best associates with early recanalization. We retrospectively analyzed consecutive patients with large vessel occlusion transferred from primary stroke centers to a tertiary comprehensive stroke center in Melbourne, Australia, for possible endovascular thrombectomy from January 2018 to December 2022. Absolute and percentage changes in NIHSS between transfer, as well as other definitions of neurological improvement, were compared using receiver operating characteristic curve analysis for association with recanalization as defined by the absence of occlusion in the internal carotid artery, middle cerebral artery (M1 or M2 segments), or basilar artery on repeat vascular imaging. Six hundred and fifty-four transferred patients with large vessel occlusion were included in the analysis: mean age was 68.8±14.0 years, 301 (46.0%) were women, and 338 (52%) received intravenous thrombolytics. The proportion of extracranial internal carotid artery, intracranial internal carotid artery, M1, proximal M2, and basilar artery occlusion was 18.8%, 13.6%, 48.3%, 15.0%, and 4.3%, respectively, on initial computed tomography angiogram. Median NIHSSprimary stroke center and NIHSScomprehensive stroke center scores were 15 (interquartile range, 9-18) and 13 (interquartile range, 8-19), respectively. Early recanalization occurred in 82 (13%) patients. NIHSS reduction of ≥33% was the best tradeoff between sensitivity (64%) and specificity (83%) for identifying recanalization. NIHSS reduction of ≥33% had the highest discriminative ability to predict recanalization (area under the curve, 0.735) in comparison with other definitions of neurological improvement. One-third neurological improvement between the primary hospital and tertiary center was the best predictor of early recanalization.

Variation in Vessel Size and Angiographic Outcomes Following Stent‐Retriever Thrombectomy in Acute Ischemic Stroke: STRATIS Registry

Background Mechanical thrombectomy is established for large‐vessel occlusions in acute ischemic stroke, but the potential role in distal vessel occlusions of medium arteries is less well established. Such medium or distal arterial segments have not been assessed with respect to thrombectomy devices used during endovascular therapy. We conducted an analysis of arterial size, segmental anatomy, and stent‐retriever device performance with respect to vessel size during thrombectomy. Methods The STRATIS registry angiography core laboratory adjudicated the exact location of the occlusion, proximal, and distal device deployment, relationship to arterial bifurcations, and anatomic nomenclature. Arterial diameters were measured at all these sites. Statistical analyses examined the relationship between vessel and stent size, and arterial recanalization using expanded Thrombolysis in Cerebral Infarction reperfusion score. Results Overall, 665 patients with stroke were included following thrombectomy using various Solitaire device sizes, including Solitaire 4×40, Solitaire 6×30, Solitaire 4×20, Solitaire 6×20, and Solitaire 4×15. Arterial diameter at the occlusion site was a median of 2.17 mm (interquartile range [IQR], 1.88–2.60 mm) in the distal M1, 1.67 mm (IQR, 1.47–2.06 mm) in the proximal M2 middle cerebral artery, 1.50 mm (IQR, 1.15–1.61 mm) in the distal M2 middle cerebral artery, 1.24 mm (IQR, 1.11–1.24 mm) in the M3 middle cerebral artery, and 1.88 mm (IQR, 1.49–1.94 mm) in the P1 posterior cerebral artery. Expanded Thrombolysis in Cerebral Infarction 2b to 3 reperfusion was achieved in all M3 or P1 segment occlusions. The rate of first‐pass recanalization was significantly higher in patients with medium (0.75–2 mm) versus large (&gt;2 mm) vessel occlusion (69.5% versus 57.1%; P = 0.003). Conclusion Considerable overlap was noted between arterial sizes at occlusion sites carrying different segmental arterial nomenclature or vessel names. Substantial reperfusion may be achieved with currently available mechanical thrombectomy devices in medium arteries.

Abstract TP133: Clot Burden Score Correlates Best With Hypoperfusion Volume and Predicts Final Infarct ASPECTS&lt;=3 in Anterior Circulation Ischemic Strokes

Purpose: Clot Burden Score (CBS) is a semiquantitative measure of thrombus extent on CTA for proximal anterior circulation strokes whose relationship with perfusion metrics has not been fully explored. CBS has potential added value during stroke triage if perfusion imaging is not available or suboptimal. We aimed to investigate if CBS is (1) correlated to perfusion estimates of infarct core volume, hypoperfusion volume, or collateral status, and (2) a predictor of final infarct extent without reperfusion therapy. Methods: Retrospective analysis included consecutive patients (1) arriving &lt;24 hours from onset, (2) with occlusion in the intracranial ICA, M1, M2, or A1 or combination, (3) with concurrent CTP, and (4) had followup CT or DWI during hospitalization. CBS is a 10-point negative ordinal scale: 2-points subtracted for occlusion of supraclinoid ICA, proximal M1, or distal M1, and 1-point subtracted for occlusion of infraclinoid ICA, A1, or M2. Correlation of CBS with perfusion metrics was evaluated using Spearman's rank test. Final infarct ASPECTS were scored for those without thrombolysis or thrombectomy. Multivariate logistic regression was used to identify predictors of final ASPECTS&lt;=3 (approximating &gt;=100mL). ROC analysis was evaluated to assess performance and optimal thresholds. Results: 222 patients included with median (IQR) age of 75 (65-84) and NIHSS of 18 (11-24). Median CBS was 7 (6-9) and best correlated to Tmax&gt;6s r=-0.579 (hypoperfusion volume), followed by HIR r=-0.401 (collateral status) and rCBF&lt;30% r=-0.306 (core volume), all p&lt;0.001. 71 (32.0%) untreated patients also had median CBS of 7 (6-9). CBS and Tmax&gt;6s had the strongest correlation to final ASPECTS in this subgroup, r=0.637 and r=-0.686 (both p&lt;0.001). 22 of these (30.1%) had final ASPECTS&lt;=3. Multivariate logistic regression including CBS, Tmax&gt;6s, HIR, baseline ASPECTS, and NIHSS showed only CBS as independent predictor of final ASPECTS&lt;=3 (p&lt;0.001). ROC AUC for CBS was 0.902 [95% CI: 0.819-0.985] with optimal threshold of &lt;=6 for sensitivity 86.4% and specificity 81.6%. Conclusion: CBS as a measure of thrombus extent correlates best with baseline hypoperfusion volume on CTP and independently predicts very large final infarcts (ASPECTS&lt;=3) without treatment.

Abstract TP246: Circadian Variability of the Clot Burden Score in Acute Anterior Circulation Ischemic Stroke

Background/Purpose: Fibrinolytic activity in blood plasma displays a circadian rhythm with a drop in the morning hours that may predispose to acute thrombotic events. The Clot Burden Score (CBS) is a semiquantitative measure on CT angiography (CTA) of thrombus extent in proximal anterior circulation strokes that has been correlated with functional outcome. Higher clot burden has also been shown to have lower recanalization rates with intravenous thrombolytics. We aimed to investigate whether CBS is a parameter that displays circadian variability. Methods: We performed a retrospective analysis on consecutive stroke patients presenting &lt;24 hours from symptom onset or last known well (LKW) with an occlusion in the anterior circulation confirmed on CTA. CBS was scored on a 10-point negative ordinal scale with 2-points subtracted for occlusion of the supraclinoid ICA, proximal M1, or distal M1, and 1-point subtracted for occlusion of the infraclinoid ICA, A1, or either M2 branches. No points were subtracted for occlusion distal to A1 or M2. Subjects were grouped into four 6-hour intervals, MORNING: 6:00-11:59, DAY: 12:00-17:59, EVENING: 18:00-23:59, and NIGHT: 0:00-5:59, based on the time of onset/LKW. CBS values were compared between groups using the Kruskal-Wallis test with pairwise comparisons. Results: 240 subjects were included with median age of 75 (IQR 65-84), NIHSS score of 17 (IQR 10-24), and time from onset/LKW to CTA of 5 hours (IQR 2-11). 73 subjects had onset during the MORNING, 56 during the DAY, 86 during the EVENING, and 25 during the NIGHT. The median CBS from MORNING time onset was 6 (IQR 5-9), compared to 7 (IQR 6-9) from the DAY, 7.5 (IQR 6-9) from the EVENING, and 7 (IQR 5-8.5) from the NIGHT. CBS was significantly lower in the MORNING compared to the EVENING, p=0.037. CBS was not significantly different between all other pairwise comparisons, p&gt;0.107. Conclusion: CBS as a measure of thrombus extent in proximal anterior circulation strokes on CTA appears to show circadian variability, with lower scores (higher clot burden) during MORNING onset (6:00-11:59) than the EVENING (18:00-23:59). This may have implications for future studies of chronotherapeutic protocols.

Abstract 41: Conventional vs Advanced Imaging for the Selection of Stroke Therapy in the Extended Window (VESTA Study)

Background: The optimal imaging modality for treatment selection in the extended stroke window is uncertain. VESTA study (NCT05299034) compared conventional imaging (noncontrast CT + CT angiography) with advanced imaging (adding perfusion) in extended window stroke patients, focusing on EVT selection rate, safety and functional outcome. Methods: From the prospective Catalan Stroke Registry (CICAT, 29 centers) ischemic stroke patients within 6-24h of symptom onset and NIHSS ≥6 (Jan 2019 -Dec 2021) were selected. Imaging modality was decided according to the local site protocol. Images were re-evaluated by a central core lab with full access to each patient’s images. LVO was defined as intracranial ICA, M1 or proximal M2 occlusion. Blinded investigators centrally assessed 90-day functional independence, defined as mRS≤2. We employed a propensity score matching algorithm to adjust for age, sex, NIHSS, established infarct, and time from onset to arrival. Results: We included 1405 patients in the analysis (median age 76y, median NIHSS 11; 48% women). Conventional imaging was performed in 48% of patients, while 52% received advanced imaging. Patients receiving conventional vs. advanced imaging showed lower NIHSS (11 vs. 12, p=0.006), and lower rates of LVO (45% vs. 58%, p&lt;0.001) and EVT indication (33% vs. 41%, p=0.01). Demographics and time metrics were comparable between techniques. The matched adjusted analysis showed no differences between modalities in 90-day functional independence (OR=0.9 [0.7;1.2]), mortality (1.18 [0.9;1.6]), or symptomatic hemorrhage (OR=1.35 [0.47;3.8]). The figure displays subgroup analysis for patients arriving at a comprehensive stroke center and for patients with anterior LVO. Conclusions: Advanced imaging allowed the identification of more occlusions and the selection of more patients for EVT; however, patients undergoing either conventional or advanced imaging had similar clinical outcomes at 90 days.

Endovascular thrombectomy for large ischemic strokes: meta-analysis of six multicenter randomized controlled trials

BackgroundSix randomized controlled trials have concluded their investigations on the efficacy and safety of endovascular thrombectomy (EVT) for patients with large infarcts.To synthesize the results from six trials which met...

Effect of Intravenous Thrombolysis Prior to Mechanical Thrombectomy According to the Location of M1 Occlusion.

The additive effects of intravenous thrombolysis (IVT) before mechanical thrombectomy (MT) remain unclear. We aimed to investigate the efficacy and safety of IVT prior to MT depending on the location of M1 occlusion. We reviewed the cases of patients who underwent MT for emergent large-vessel occlusion of the M1 segment. Baseline characteristics as well as clinical and periprocedural variables were compared according to the location of M1 occlusion (i.e., proximal and distal M1 occlusion). The main outcome was the achievement of functional independence (modified Rankin Scale score, 0-2) at 3 months after stroke. The main outcomes were compared between the proximal and distal groups based on the use of IVT before MT. Among 271 patients (proximal occlusion, 44.6%; distal occlusion, 55.4%), 33.9% (41/121) with proximal occlusion and 24.7% (37/150) with distal occlusion underwent IVT prior to MT. Largeartery atherosclerosis was more common in patients with proximal M1 occlusion; cardioembolism was more common in those with distal M1 occlusion. In patients with proximal M1 occlusion, there was no association between IVT before MT and functional independence. In contrast, there was a significant association between the use of IVT prior to MT (odds ratio=5.30, 95% confidence interval=1.56-18.05, P=0.007) and functional independence in patients with distal M1 occlusion. IVT before MT was associated with improved functional outcomes in patients with M1 occlusion, especially in those with distal M1 occlusion but not in those with proximal M1 occlusion.

Effect of computed tomography vs. computed tomography perfusion on mechanical thrombectomy outcomes within 6hours.

It is unclear which selection strategy, plain CT vs. CT perfusion (CTP), is more powerful in predicting outcome after mechanical thrombectomy (MT). We aimed to compare the effect of plain CT and CTP in predicting outcome after MT within 6h. We conducted a prospective analysis of a retrospective cohort from our single-center study, which had occlusion of the internal carotid artery and middle cerebral artery up to the proximal M2 segment and received MT within 6h. According to the Alberta Stroke Program Early CT Score (ASPECTS), patients were divided into a high-ASPECTS group (≥ 6) and a low ASPECTS group (< 6). Similarly, patients were divided into mismatch and no-mismatch groups according to the DEFUSE3 criteria for CTP. A good outcome was defined as a 90-day modified Rankin Scale (mRS) score of ≤ 3. Univariate and binary logistic regression analyses were used to investigate the association between different imaging modality and 90-day mRS score, and mortalities, respectively. The high ASPECTS group included 307 patients (89.2%). The mismatch group included 189 (54.9%) patients meeting the DEFUSE3 criterion. Compared to the low ASPECTS group, the high ASPECTS group had a good outcome (odds ratio (OR), 2.285; [95% confidence interval (CI) (1.106, 4.723)], p = 0.026) and lower mortality (OR, 0.350; [95% CI (0.163, 0.752)], p = 0.007). However, there were no significant differences in good outcomes and mortality between the mismatch and no-mismatch groups. Compared with plain CT, CTP does not provide additional benefits in the selection of patients suitable for MT within 6h. CT perfusion is not superior to plain CT for the prediction of clinical outcomes when selecting patients for mechanical thrombectomy in the first 6h. In that clinical setting, plain CT may be safe in the absence of perfusion data. •The advantage of CT perfusion (CTP) over CT in pre-mechanical thrombectomy (MT) screening has not been proven for patients witha large infarct core. •CTP is not better than plain CT in predicting good outcome following MT within 6h. •Plain CT is sufficient for selecting patients suitable for MT within 6h of large artery occlusion.

Evaluation of CINA® LVO artificial intelligence software for detection of large vessel occlusion in brain CT angiography

ObjectiveTo systematically evaluate the ability of the CINA® LVO software to detect large vessel occlusions eligible for mechanical thrombectomy on CTA using conventional neuroradiological assessment as gold standard. MethodsRetrospectively, two hundred consecutive patients referred for a brain CTA and two hundred patients that had been subject for endovascular thrombectomy, with an accessible preceding CTA, were assessed for large vessel occlusions (LVO) using the CINA® LVO software. The patients were sub-grouped by occlusion site. The original radiology report was used as ground truth and cases with disagreement were reassessed. Two-by-two tables were created and measures for LVO detection were calculated. ResultsA total of four-hundred patients were included; 221 LVOs were present in 215 patients (54 %). The overall specificity was high for LVOs in the anterior circulation (93 %). The overall sensitivity for LVOs in the anterior circulation was 54 % with the highest sensitivity for the M1 segment of the middle cerebral artery (87 %) and T-type internal carotid occlusions (84 %). The sensitivity was low for occlusions in the M2 segment of the middle cerebral artery (13 % and 0 % for proximal and distal M2 occlusions respectively) and in posterior circulation occlusions (0 %, not included in the intended use of the software). ConclusionsLVO detection sensitivity for the CINA® LVO software differs largely depending on the location of the occlusion, with low sensitivity for detection of some LVOs potentially eligible for mechanical thrombectomy. Further development of the software to increase sensitivity to all LVO locations would increase the clinical usefulness.

Abstract 002: Examining Pulling Force Using Combined Stentreiver and Aspiration Technique in a Medium Vessel Thrombectomy Model

Introduction With the advent of smaller stent retrievers (SR) and aspiration catheters (AC) capable of accessing more distal locations, distal and medium vessel occlusions (DMVO) are emerging as promising targets for endovascular thrombectomy (EVT). However, considering the vulnerability of distal vessels to injury, it is imperative to understand the safety of various frontline techniques in these challenging scenarios. Using a vascular flow model, we sought to investigate the optimal size, strategy, and positioning of a stent retriever and aspiration catheter to minimize the pulling force exerted on the M2 vasculature. Methods We used a silicone vascular flow model with moderate tortuosity that replicated the left‐sided anterior circulation, including middle cerebral artery (MCA) branches in the M2 territory. An 8 French Cook Shuttle guide sheath was inserted coaxially with a Catalyst 7‐132 cm aspiration catheter and TrevoTrak 21 microcatheter. To measure pulling force, an Imada force gauge DST‐1A was placed at the M2 and a DST‐11A at the proximal end of the microcatheter. The Solitaire 4x20 mm Solitaire stent‐retriever was pulled at 4 mm/sec with the AC in the proximal cavernous carotid segment (NoAsp), proximal M1 (M1P), and distal M1 (M1D), a total of 8 times per AC position, using the ingestion technique. The pinching technique was also examined using the 4x20mm stent. Results The average pulling force measured on M2 using the 4x20mm stent was 169.1mN with the AC docked in the proximal NoAsp position, 26.5mN with the AC at M1P, and 23.0mN at M1D (p&lt;0.0001). The difference in pulling force between M1P and M1D was not significant (p=0.472). The average pulling force exerted on M2 from pinching the 4x20mm stent with the AC at M1D, rather than ingestion of the stent at M1D, was 62.9mN. Average pulling force was noted to decrease from the first to the last run in most cases, with an average drop of 26.4% at the fourth run. Conclusion ADAPT and stent‐retrieval have recently been shown to be comparable in DMVO (1), however some studies have suggested a combined approach may reduce bleeding complications compared to stent‐retrieval alone (2). In our in‐vitro model, we demonstrated that positioning the AC in M1 (M1D or M1P) reduced the pulling force exerted by the stent‐retriever on M2 compared with AC placement in the cavernous carotid (NoAsp). The pulling force exerted from pinching the 4x20mm stent with the AC at M1D was higher than with the ingestion technique, for which the explanation is uncertain, but may be due to the additional friction in the M1 segment. Taken together, these findings suggest a combined approach decreases frictional pulling force during stent‐retrieval and is safer than SR alone. We also note that the pulling force of each stent decreased after its third usage, in line with the manufacturer’s instructions for use, which suggest no more than 3 retrievals per stent (3). Future experiments will compare a wider range of techniques using stents of varying sizes to better clarify factors associated with decreased pulling force in EVT.

Abstract 064: The Pushability of Commonly Used Microwires in Neuroendovascular Procedures

Introduction In distal and medium‐vessel occlusions (DMVOs), there are increasing opportunities to deliver devices through tortuous and medium sized arteries. However, this comes at the risk of microwire perforation during distal microcatheter advancement for navigation in these curved, slender vessels, leading to hemorrhagic complications. Currently, microwires with a range of stiffness levels are available. However, it is unclear how the variations in stiffness and the relative positioning of the microwire and microcatheter may affect the force applied to the vessel wall. Few studies have compared objective metrics across different commonly used devices. We sought to compare the pushability of various Synchro Select and Chikai microwires using both proximal and distal support. Methods In a moderate tortuosity, silicone flow model of the middle cerebral artery (MCA) branches, we tested 0.014” nitinol microwires (Synchro Select Soft, Standard, or Support), or 0.014” stainless steel microwires (Chikai, Black, and Black Soft) in a TrevoTrak 21 microcatheter docked either in the proximal M1 segment or distal M2 segment. Applied force was measured using an Imada force gauge DST‐1A at the M2 ten times for each experiment. The slope, measured in mN per mm, of the applied distal force during the maximal pushing period was calculated. Results The average slope of the pushing force within a distal microcatheter was 10.64 mN/mm with a Synchro Soft, 10.85 mN/mm with a Standard, and 15.28 mN/mm with a Support microwire (p &lt; 0.0001). The average slope of the pushing force in a proximal microcatheter was 1.61 mN/mm with a Synchro Soft, 3.15 mN with a Synchro Standard, and 3.87 mN with a Synchro Support microwire (p &lt;0.001). With the Chikai microwires, the average slope of the pushing force within a distal microcatheter was 12.48 mN/mm with a Chikai Black Soft wire, 12.82 mN/mm with a Chikai Black microwire, and 14.11 mN/mm using a Chikai microwire (p=0.801). Within a proximal microcatheter, the average maximal force was 2.42 mN/mm using a Chikai Black Soft wire, 3.16 mN/mm using Chikai Black, and 3.91 mN/mm using the Chikai wire (p &lt; 0.001). Conclusion This study demonstrated that stiffer microwires push the arterial wall with significantly greater force within a microcatheter close to the wall. Pushability of the microwire significantly dropped across all microwires when the microcatheter was positioned more proximally. This is the first known report of the pushability of commonly used microsystems in neuroendovascular procedures.

Abstract 198: Case Report: Thrombectomy using Zoom Reperfusion System In Pediatric Acute Ischemic Strokes

Introduction Zoom reperfusion system (Imperative Care, CA) has proven to be promising for use in mechanical thrombectomies in adults but has not been described in pediatrics to our knowledge. We present two cases of a 14‐year‐old boy with acute right middle cerebral artery (MCA) syndrome and a 10‐year‐old boy with acute left MCA syndrome who underwent mechanical thrombectomy using Zoom Reperfusion System safely with TICI 2B and 3 recanalization respectively. Methods Case report and review of literature Results Case 1: 14‐year‐old previously healthy boy presented to our facility for acute right MCA syndrome secondary to right supraclinoid internal carotid artery (ICA) occlusion. After receiving alteplase, patient was taken for mechanical thrombectomy. After femoral access was obtained, an 8‐French sheath was introduced into the right femoral artery through which a Zoom 88 catheter and 5‐French BERN catheter (Terumo) were coaxially advanced over a Terumo Glidewire into the right common carotid artery. Under roadmap guidance, the Zoom 88 catheter was parked at the lacerum ICA segment with BERN catheter and Glidewire then removed. Angiogram demonstrated complete occlusion of the ICA just past the origin of the ophthalmic artery. Via Zoom 88 catheter, a Zoom 71 catheter was then navigated to the face of clot over a velocity microcatheter (Penumbra) and synchro 2 wire system (Stryker) which was then removed. The vacuum manifold was then attached to Zoom 71 catheter and allowed to engage with the clot for 3 minutes prior to withdrawal into the Zoom 88 catheter. TICI 2B recanalization was achieved with sub‐occlusive thrombus within the proximal M1 segment. Retrieval of the sub‐occlusive thrombus in the M1 segment was performed with TREVO stentriever (Stryker). Procedure was complicated by vasospasm in the A1 and M2 segments which resolved with milrinone and verapamil infused through the Zoom 88 catheter. Case 2: 10‐year‐old with left hypoplastic heart syndrome presented to our facility for acute left MCA syndrome due to left ICA terminus occlusion. Mechanical thrombectomy was performed after receiving alteplase. Femoral artery access was obtained with a 8‐French sheath, through which Zoom 88 catheter and 5‐French select catheter (Penumbra) were advanced over Terumo Glidewire into the left common carotid artery. Under roadmap guidance, the Zoom 88 catheter was parked at the ophthalmic segment of ICA with select catheter and Glidewire then removed. Angiogram demonstrated complete occlusion at the ICA terminus. Zoom 71 catheter was introduced through Zoom 88 catheter and navigated to the face of clot at the ICA terminus over velocity microcatheter (Penumbra) and synchro wire system (Stryker) which was then removed. Zoom 71 was then attached to a vacuum manifold to engage with the clot for 90 seconds. TICI 2A recanalization after first pass was achieved with flow restoration in anterior cerebral artery but none in the MCA.TICI 3 recanalization was achieved after second pass. Conclusion The use of Zoom reperfusion system potentially proves to be safe for use in the pediatric age group with good recanalization results and no intraoperative or postoperative complications.