Medium Vessel Occlusions Research Articles

Development of machine learning models for predicting outcome in patients with distal medium vessel occlusions: a retrospective study.

While numerous prognostic factors have been reported for large vessel occlusion (LVO)-acute ischemic stroke (AIS) patients, the same cannot be said for distal medium vessel occlusions (DMVOs). We used machine learning (ML) algorithms to develop a model predicting the short-term outcome of AIS patients with DMVOs using demographic, clinical, and laboratory variables and baseline computed tomography (CT) perfusion (CTP) postprocessing quantitative parameters. In this retrospective cohort study, consecutive patients with AIS admitted to two comprehensive stroke centers between January 1, 2017, and September 1, 2022, were screened. Demographic, clinical, and radiological data were extracted from electronic medical records. The clinical outcome was divided into two categories, with a cut-off defined by the median National Institutes of Health Stroke Scale (NIHSS) shift score. Data preprocessing involved addressing missing values through imputation, scaling with a robust scaler, normalization using min-max normalization, and encoding of categorical variables. The data were split into training and test sets (70:30), and recursive feature elimination (RFE) was employed for feature selection. For ML analyses, XGBoost, LightGBM, CatBoost, multi-layer perceptron, random forest, and logistic regression algorithms were utilized. Performance evaluation involved the receiver operating characteristic (ROC) curve, precision-recall curve (PRC), the area under these curves, accuracy, precision, recall, and Matthews correlation coefficient (MCC). The relative weights of predictor variables were examined using Shapley additive explanations (SHAP). Sixty-nine patients were included and divided into two groups: 35 patients with favorable outcomes and 34 patients with unfavorable outcomes. Utilizing ten selected features, the XGBoost algorithm achieved the best performance in predicting unfavorable outcomes, with an area under the ROC curve (AUROC) of 0.894 and an area under the PRC curve (AUPRC) of 0.756. The SHAP analysis ranked the following features in order of importance for the XGBoost model: mismatch volume, time-to-maximum of the tissue residue function (Tmax) >6 s, diffusion-weighted imaging (DWI) volume, neutrophil-to-platelet ratio (NPR), mean corpuscular volume (MCV), Tmax >10 s, hemoglobin, potassium, hypoperfusion index (HI), and Tmax >8 s. Our ML models, trained on baseline quantitative laboratory and CT parameters, accurately predicted the short-term outcome in patients with DMVOs. These findings may aid clinicians in predicting prognosis and may be helpful for future research.

A review of acute ischemic stroke caused by distal, medium vessel occlusions.

Acute ischemic stroke (AIS) due to distal, medium vessel occlusion (DMVO) is increasingly recognized as the next frontier for mechanical thrombectomy. Distal, medium vessel occlusions are typically defined as an occlusion in the following arteries: anterior cerebral artery, M2-M4 segments of the middle cerebral artery, posterior cerebral artery, posterior inferior cerebellar artery, anterior inferior cerebellar artery, and superior cerebellar artery. It is estimated that 25-40% of all AIS is due to DMVO. Because of the large burden of DMVO, the frequency of literature published regarding these occlusions has greatly increased in recent years. Furthermore, treatment modalities have been created specifically for DMVOs. Due to the rapidly evolving literature on this topic, remaining up to date on DMVO definitions, anatomy, management, imaging, and clinical course is difficult. In this review article, we synthesized existing literature regarding the aforementioned topics and discussed future directions.

The effect of occlusion location and technique in mechanical thrombectomy for minor stroke.

Endovascular mechanical thrombectomy (MT) is an established treatment for large vessel occlusion strokes with a National Institutes of Health Stroke Scale (NIHSS) score of 6 or higher. Data pertaining to minor strokes, medium, or distal vessel occlusions, and most effective MT technique is limited and controversial. A multicenter retrospective study of all patients treated with MT presenting with NIHSS score of 5 or less at 29 comprehensive stroke centers. The cohort was dichotomized based on location of occlusion (proximal vs. distal) and divided based on MT technique (direct aspiration first-pass technique [ADAPT], stent retriever [SR], and primary combined [PC]). Outcomes at discharge and 90 days were compared between proximal and distal occlusion groups, and across MT techniques. The cohort included 759 patients, 34% presented with distal occlusion. Distal occlusions were more likely to present with atrial fibrillation (p = 0.008) and receive IV tPA (p = 0.001). Clinical outcomes at discharge and 90 days were comparable between proximal and distal groups. Compared to SR, patients managed with ADAPT were more likely to have a modified Rankin Scale of 0-2 at discharge and at 90 days (p = 0.024 and p = 0.013). Primary combined compared to ADAPT, prior stroke, multiple passes, older age, and longer procedure time were independently associated with worse clinical outcome, while successful recanalization was positively associated with good clinical outcomes. Proximal and distal occlusions with low NIHSS have comparable outcomes and safety profiles. While all MT techniques have a similar safety profile, ADAPT was associated with better clinical outcomes at discharge and 90 days.

Current challenges in the endovascular treatment of medium vessel occlusions

Medium vessel occlusions (MeVOs) account for 25%−40% of acute ischemic stroke (AIS). While mechanical thrombectomy is the standard-of-care for selected patients with large vessel occlusion (LVO), there is currently a lack of level I evidence of the safety and efficacy of endovascular treatment (EVT) for MeVOs. Several randomized clinical trials (RCTs) have attempted to answer this relevant clinical question. However, several questions related to the EVT of MeVO stroke may remain unanswered even after successful completion of these trials: What is the optimal EVT approach for secondary MeVOs? Is EVT beneficial for posterior circulation MeVOs? Is pre-EVT intravenous thrombolysis better than EVT alone? What is the optimal first line thrombectomy technique for these lesions? Are the outcome assessment tools used for LVOs appropriate for MeVOs? Upcoming evidence and the natural evolution and development of new technologies will aid in overcoming these challenges.

Incidence and outcome of perforations during medium vessel occlusion compared with large vessel occlusion thrombectomy

BackgroundVessel perforation during thrombectomy is a severe complication and is hypothesized to be more frequent during medium vessel occlusion (MeVO) thrombectomy. The aim of this study was to compare the...

The incidence of medium vessel occlusions: a population-based study.

The incidence of medium vessel occlusion (MeVO) is not well known. The objective of our study is to perform a population-based assessment to estimate the incidence of MeVOs. Consecutive patients from Olmsted County, Minnesota who presented for acute ischemic stroke seen at Mayo Clinic Hospital from 1/1/2018 to 12/31/2020 who were found to have a MeVO were included in this study. MeVO was defined as occlusion at or beyond the level of the middle cerebral artery M2 segment, anterior cerebral artery A2 segment, posterior cerebral artery P1 segment, and cerebellar arteries. Census data for Olmsted County was obtained from the United States Census Bureau from the year 2020. A total of 1,718 patients were screened for the study, 77 patients fulfilled inclusion criteria to be included in the study. Presenting NIHSS was 9 (± 7). The population of Olmsted County was estimated to be 162,847. The incidence rate for MeVO was 16 cases (95% CI 12-19) per 100,000 people per year. Based on estimates of the US population in 2020 of 331,449,281 people, we estimate there are 52,236 (95% CI 40,635-64,002) new cases of MeVOs per year. As the only stroke center in Olmsted County, we have been able to estimate the incidence of ischemic stroke due to MeVO. While the incidence of MeVOs is less than both large and small vessel occlusions, they still represent a significant proportion of strokes with significant morbidity and mortality that would benefit from further studies in both acute intervention and prevention.

Pretreatment brain CT perfusion thresholds for predicting final infarct volume in distal medium vessel occlusions.

Quantitative CT perfusion (CTP) thresholds for assessing the extent of ischemia in patients with acute ischemic stroke (AIS) have been established; relative cerebral blood flow (rCBF) <30% is typically used for estimating estimated ischemic core volume and Tmax (time to maximum) >6seconds for critical hypoperfused volume in AIS patients with large vessel occlusion (LVO). In this study, we aimed to identify the optimal threshold values for patients presenting with AIS secondary to distal medium vessel occlusions (DMVOs). In this retrospective study, consecutive AIS patients with anterior circulation DMVO who underwent pretreatment CTP and follow-up MRI/CT were included. The CTP data were processed by RAPID (iSchemaView, Menlo Park, CA) to generate estimated ischemic core volumes using rCBF <20%, <30%, <34%, and <38% and critical hypoperfused volumes using Tmax (seconds) >4, >6, >8, and >10. Final infarct volumes (FIVs) were obtained from follow-up MRI/CT within 5days of symptom onset. Diagnostic performance between CTP thresholds and FIV was assessed in the successfully and unsuccessfully recanalized groups. Fifty-five patients met our inclusion criteria (32 female [58.2%], 68.0±12.1years old [mean±SD]). Recanalization was attempted with intravenous tissue-type plasminogen activator and mechanical thrombectomy in 27.7% and 38.1% of patients, respectively. Twenty-five patients (45.4%) were successfully recanalized. In the successfully recanalized patients, no CTP threshold significantly outperformed what is used in LVO setting (rCBF<30%). All rCBF CTP thresholds demonstrated fair diagnostic performances for predicting FIV. In unsuccessfully recanalized patients, all Tmax CTP thresholds strongly predicted FIV with relative superiority of Tmax >10seconds (area under the receiver operating characteristic curve=.875, p=.001). In AIS patients with DMVOs, longer Tmax delays than Tmax >6seconds, most notably, Tmax >10seconds, best predict FIV in unsuccessfully recanalized patients. No CTP threshold reliably predicts FIV in the successfully recanalized group nor significantly outperformed rCBF<30%.

Feasibility and safety of ADAPT in acute distal posterior cerebral artery occlusions

PurposeThe direct aspiration first pass technique (ADAPT) is an effective and safe endovascular treatment for distal medium vessel occlusions (DMVO) of the anterior circulation. Clinical experience with ADAPT in the distal posterior circulation, however, is still limited and published data is scarce. In this original work, feasibility, safety and efficacy of ADAPT with distal access catheters (DAC) for treatment of acute distal posterior cerebral artery occlusions (DPCAOs) is evaluated. MethodAll acute ischemic stroke patients between 2017 and 2022 with primary or secondary DPCAOs in the P2 or P3 segment, that underwent thrombectomy of the DPACO using ADAPT with DACs as frontline therapy, were identified. Demographic data, recanalization rates, procedural safety, and clinical outcome were assessed. ResultsTwenty-four patients with primary (n = 6) or secondary (n = 18) DPCAOs (P2: 21/24; P3: 3/24) were included. Median NIHSS score at admission was 14.5 (IQR 9.5). In all cases, the DPCAO could be reached with the DAC. Successful revascularization (DMVO-p-TICI ≥ 2b) with ADAPT was achieved in 79.2% (19/24), including a first pass effect of 62.5% (15/24), leading to complete recanalization (DMVO-p-TICI 3). Median number of passes was 1 (range 1–2). No complications related to distal PCA aspiration thrombectomy occurred. Median NIHSS and mRS scores at discharge were 4 (IQR 8) and 3 (IQR 2), respectively. ConclusionsADAPT appears to be feasible, safe and effective for the treatment of acute DPCAOs in the setting of different occlusion patterns. High revascularization rates without procedural complications can be achieved. Further studies are needed to consolidate these results.

Effect of anesthetic strategies on distal stroke thrombectomy in the anterior and posterior cerebral artery

BackgroundNumerous questions regarding procedural details of distal stroke thrombectomy remain unanswered. This study assesses the effect of anesthetic strategies on procedural, clinical and safety outcomes following thrombectomy for distal medium...

Prediction of 90‐Day Home Time Among Patients With Medium‐Vessel Occlusion Undergoing Endovascular Thrombectomy

Background The benefit of endovascular thrombectomy for medium‐vessel occlusion (MeVO) strokes is unclear. We used 90‐day home time to explore outcomes in patients with MeVO versus large‐vessel occlusions treated with endovascular thrombectomy. Methods Data are from the QuICR (Quality Improvement and Clinical Research) provincial stroke registry and linked administrative data to identify patients who underwent endovascular thrombectomy in our center from January 2015 to December 2020. Imaging data were scored by 2‐physician consensus. We defined MeVO as occlusion beyond and including M2–middle cerebral artery, A2–anterior cerebral artery, or P2–posterior cerebral artery segments. Successful reperfusion was defined as Thrombolysis in Cerebral ischemia grades (≥2b/3). The primary outcome was patient home time (the number of nights a patient is back at their premorbid living situation without an increase in level of care within 90 days of the stroke) using random forest regression. Covariate contribution to home time was determined using partial dependence plots. Results Among 663 patients who underwent endovascular thrombectomy, 139 (20.9%) had MeVO (median age, 71 years; 50.4% women; median National Institutes of Health Stroke Scale, 16). The majority (82%) had good pial collaterals, 10.4% had a tandem extracranial carotid occlusion or stenosis, and 41.7% received intravenous thrombolysis. The most common site of occlusion was M2–middle cerebral artery (58.3%). One hundred eighteen (86.7%) patients achieved successful reperfusion (Thrombolysis in Cerebral Ischemia grades ≥2b/3). Using partial dependence plots, the mean predicted home times were similar in patients with MeVO (45.5 days) versus large‐vessel occlusions (44.6 days). Factors predicting lower 90‐day home time in patients with MeVOs were diabetes (−8.7 days), hypertension (−6.5 days), and atrial fibrillation (−3.5 days). There was no meaningful difference in predicted 90‐day home‐time by sex, baseline National Institutes of Health Stroke Scale, collateral grade, or thrombolysis. Conclusion Patients with MeVO who are selected for endovascular therapy with similar demographic and clinical profiles to large‐vessel occlusions can achieve similar 90‐day home time outcomes to large‐vessel occlusions.

Maximum Euclidean Deflection: A Novel Metric For Safety Of Neurovascular Devices In An In-vitro Stroke Model (P3-5.010)

<h3>Objective:</h3> To enable effective comparative analyses, there is a need to develop an objective in-vitro safety metric for new endovascular thrombectomy devices. <h3>Background:</h3> Endovascular thrombectomy (EVT) devices are evolving rapidly to improve safety and efficacy of EVT-mediated recanalization of large vessel occlusion strokes, and to access medium and distal vessel occlusions. <h3>Design/Methods:</h3> We utilized three FDA-approved stent-retrievers (4mm diameter; variable lengths) and deployed them in an in-vitro ischemic stroke bench model (Sim Agility, Mentice Inc., Sweden). The stent-retrievers were deployed in the M1 segment of the middle cerebral artery of the model using a system comprised of an 0.014inch guide wire and 0.021inch microcatheter. After unsheathing in the M1 segment, in the absence of a blood clot, the microcatheter was withdrawn back into the petrous internal carotid artery, and the whole system was withdrawn at a rate of 5mm/second. Maximum deflection of the terminal internal carotid was measured in 3 axes using a specialized camera set-up. <h3>Results:</h3> A total of 3 passes were performed for each stent-retriever (stent-A, stent-B, and stent-C). Maximum deflection of the terminal internal carotid artery (from resting position to largest displacement during stent-retrieval withdrawal) was measured in 3 planes (Table)- Maximum Euclidean Deflection (MED) ranged from 6.1 to 9.1mm. Deflection varied based on 3 stent-retriever designs and the plane of measurement. Figure demonstrates deflections as seen in Stent-A. <h3>Conclusions:</h3> Withdrawing an unsheathed stent-retriever from the middle cerebral artery leads to significant deflection of the internal carotid artery terminus in an in-vitro stroke model. The degree of deflection varies based on stent-retriever design. Further studies are required to examine predictors and impact of the deflection. <b>Disclosure:</b> Dr. Desai has nothing to disclose. Dr. Catapano has nothing to disclose. Neil Majmundar has nothing to disclose. Mrs. Cooper has nothing to disclose. Mrs. Flynn has nothing to disclose. Mr. Jones has nothing to disclose. Andrew Ducruet has received personal compensation in the range of $500-$4,999 for serving as a Consultant for koswire. Andrew Ducruet has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for stryker. Andrew Ducruet has received personal compensation in the range of $500-$4,999 for serving as a Consultant for medtronic. Andrew Ducruet has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for cerenovus. Andrew Ducruet has received personal compensation in the range of $500-$4,999 for serving as a Consultant for oculus. Andrew Ducruet has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for penumbra. Dr. Jadhav has nothing to disclose.

Diagnostic accuracy of CT angiography and CT perfusion imaging for detecting distal medium vessel occlusions: Protocol for a systematic review and meta-analysis.

Distal medium vessel occlusions (DMVOs) represent 25-40% of all acute ischemic strokes (AIS). DMVO clinical syndromes are heterogenous, but as eloquent brain regions are frequently involved, they are often disabling. Since current intravenous fibrinolytic therapies may fail to recanalize up to two-thirds of DMVOs, endovascular treatment is progressively being considered in this setting. Nevertheless, the optimal imaging method for diagnosis remains to be defined. Stroke centers that use computed tomography as a routine stroke imaging approach rely on either isolated computed tomography angiography (CTA) or combined perfusion (CTP) studies. Despite a simplified non-CTP-dependent approach seeming reasonable for large vessel occlusion AIS diagnosis, CTP may still hold advantages for DMVOs workup. Therefore, this systematic review aims to compare the diagnostic performance of CTA and CTP in detecting DMVOs. We will perform a systematic search in PubMed, EMBASE, Web of Science Core Collection, and Cochrane Central Register of Controlled Trials. In addition, grey literature and ClinicalTrials.gov will be scanned. We will include any type of study that presents data on the diagnostic accuracy of CTA and/or CTP for detecting DMVOs. Two authors will independently review retrieved studies, and any discrepancies will be resolved by consensus or with a third reviewer. Reviewers will extract the data and assess the risk of bias in the selected studies. Data will be combined in a quantitative meta-analysis following the guidelines provided by the Cochrane Handbook for Systematic Reviews of Interventions. We will assess cumulative evidence using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. This will be the first systematic review and meta-analysis that compares two different imaging approaches for detecting DMVOs. This study may help to define optimal acute ischemic stroke imaging work-up. PROSPERO registration: CRD42022344006.

Mechanical thrombectomy of distal cerebral vessel occlusions of the anterior circulation

Mechanical thrombectomy (MT) is frequently performed for distal medium vessel occlusions (DMVO) of the anterior circulation in acute stroke patients. However, evidence for its clinical benefit remains scarce. In this study, we aim to investigate clinical course and safety outcomes of MT in comparison to standard medical therapy (SMT) in DMVO. This single-center retrospective observational study included 138 consecutive patients treated for DMVO of the anterior circulation between 2015 and 2021. To reduce the risk of selection bias, propensity score matching (PSM) of patients with MT versus SMT was performed for the covariates NIHSS and mRS at admission. Out of all 138 patients, 48 (34.8%) received MT and 90 (65.2%) received SMT only. Overall, patients treated with MT showed significantly higher NIHSS and mRS scores at admission. Post 1:1 PSM, there was a trend toward a better NIHSS improvement in patients with MT (median 4 vs. 1, P = 0.1). No significant differences were observed in the occurrence of symptomatic intracranial hemorrhage or mortality between the groups before and after PSM. A subgroup analysis showed significantly higher NIHSS improvement (median 5 versus 1, P = 0.01) for patients with successful MT (≥ mTICI 2b). Mechanical thrombectomy for distal medium vessel occlusions (DMVO) in the anterior circulation appeared safe and feasible. Successful recanalization was associated with clinical improvement. Larger, multi-center, randomized-controlled trials are required to corroborate these findings.

Mechanical thrombectomy with Q catheter in stroke caused by primary and secondary distal and medium vessel occlusions.

The MIVI Q aspiration catheters have been shown to achieve significantly greater flow rates than other intracranial aspiration catheters in vitro. We describe our initial real-world experience with the MIVI Q catheter in emergent acute ischemic stroke (AIS) caused by distal and medium vessel occlusions (DMVO). Data was collated from a prospectively maintained database which included patients from October 2019 to December 2022. Occlusion demographics, thrombectomy technique, reperfusion scoring, procedural complications and disposition were assessed. The primary outcome of interest was rate of successful reperfusion defined as thrombolysis in cerebral infarction (TICI) score 2b-3. Secondary outcomes included rate of first pass effect (FPE) and complications. We included 64 target occlusions in 51 patients. The Q catheter successfully reached the DMVO in all occlusions. Successful reperfusion was achieved in 49/64 (76.6%) occlusions, and TICI scores were similar for primary and secondary DMVOs (P value = 0.41). FPE was achieved in 39/64 (60.9%) occlusions and did not differ between primary and secondary DMVOs (P value = 0.13). Reperfusion hemorrhage occurred in 3/64 (4.7%) cases, small volume subarachnoid hemorrhage in 3/64 (4.7%) cases, and small hemorrhagic transformation in 1/64 (1.6%) cases; the rate of complications did not differ based on primary versus secondary DMVO (P value = 0.29). The MIVI Q catheter is both safe and effective. Our real-world experience supports the superior flow rates demonstrated in vitro and translates into high rates of successful reperfusion in AIS caused by DMVO in clinical practice.

560 Mechanical Thrombectomy Versus Best Medical Therapy for Medium Vessel Occlusions: A Cost-Effective Analysis Using Local Get with the Guidelines Registry Data

INTRODUCTION: Equipoise exists in regards to whether mechanical thrombectomy (MT) is superior to best medical management (BMM) in patients with acute ischemic stroke due to medium vessel occlusion (MeVO). While clinical outcome differences may not be statistically significant in prior series, MT for MeVO may still be cost-effective (CE). METHODS: The local Get with the Guidelines (GTWG) registry data was queued. Patients with MeVO documented on CTA presenting with NIHSS &gt;5 and treated with MT or BMM within 12 hours from symptom onset were included. Rates of each mRS outcomes was collected. Stroke cost data was derived from previous stroke literature including costs associated with imaging done at admission (non-contrast CT, CT Angiography, and CT perfusion), MRI 24 hours post-stroke, perfusion maps software, intravenous alteplase, physician and personnel costs, and thrombectomy. Costs associated with each mRS from presentation to 90-days and post-90 day care were collected. Utilizing the clinical data from GTWG registry and costs from the literature, TreeAge Pro was used to generate cost-effectiveness ratios (CE-ratio). RESULTS: Both the MT and BMM groups were similar in age, comorbidities, NIHSS and time to presentation. MT was found to be more cost-effective (CE-ratio 93,500) compared to BMM (CE-ratio 101,496. MT was more costly (total cumulative cost $59,840) than BMM (total cumulative cost $51,763). MT and BMM respectively had an effectiveness score of 0.64 and 0.51. CONCLUSIONS: This is one of the first CE studies comparing MT and BMM in acute ischemic strokes due to MeVO. We demonstrate based on GTWG data and costs in the literature that MT is more CE than BMM.

April 2023 Stroke Highlights.

April 2023 Stroke Highlights.

Rescue thrombolysis for medium vessel occlusion (RESCUE-TNK): Rationale and design of a phase 2 randomized trial.

The best reperfusion strategy for medium-sized vessel occlusion (MeVO) is not well established. Given the proven treatment effect of intra-arterial thrombolysis in patients with large vessel occlusion (LVO), we hypothesized that intra-arterial tenecteplase (TNK) could increase the recanalization rate of MeVO and thus improve clinical outcome. To explore the safety and efficacy of intra-arterial TNK in patients with MeVO. A maximum of 80 patients are required to test the superiority hypothesis, using power = 80% and α = 0.025 to conduct the one-sided test. Rescue treatment for mEdium veSsel oCclUsion by intra-artErial TNK (RESCUE-TNK) is a pilot, randomized, open-label, blinded end point, and multicenter trial. Eligible patients including primary MeVO as detected by the first DSA examination or secondary MeVO after endovascular treatment (EVT) for LVO will be assigned into the experimental group and control group as a ratio of 1:1. The experimental group will be treated with intra-arterial TNK (0.2-0.3 mg/min, for 20-30 min) via a microcatheter placed proximal to the site of occlusion, and the control group will be treated with routine therapy. Both groups of patients will be given standard stroke care based on the guidelines. The primary efficacy end point is successful recanalization of MeVO, defined as the expanded treatment in cerebral ischemia (eTICI) score 2b67-3 after the procedure, while the primary safety end point is symptomatic intracranial hemorrhage (sICH), defined as National Institutes of Health Stroke Scale score increase ≥4 caused by intracranial hemorrhage within 24 (-6/+24) hours after randomization. The results of RESCUE-TNK will provide evidence for the efficacy and safety of intra-arterial TNK in the recanalization of patients with MeVO.

Direct Aspiration versus Combined Technique for Distal Medium-Vessel Occlusions: Comparison on a Human Placenta Model.

Mechanical thrombectomy appears to be a promising option for distal medium-vessel occlusions, for which intravenous thrombolysis is effective but may be insufficient when used alone. This study aimed to determine the optimal technique for these distal mechanical thrombectomies using the human placenta model. Twenty-four procedures were performed, allowing comparison of direct aspiration (n = 12) versus the combined technique (n = 12). Two positions of the aspiration catheter were tested for each of these techniques: in direct contact with the clot and at a distance from it (5-10 mm). Two types of clots were tested: red blood cell-rich clots and fibrin-rich clots. First-pass recanalization and induced arterial collapse and traction were assessed. The first-pass recanalization was less frequent for direct aspiration than for the combined technique, without reaching statistical significance (41.7% versus 75.0%, P = .098). Full collapse (P < .001) and extended arterial traction (P = .001) were significantly less frequent for direct aspiration. For direct aspiration with the aspiration catheter not in direct contact with the clot, there was not a single first-pass recanalization and there was systematic arterial collapse, resulting in a no-flow in the aspiration syringe. The combined technique appears to be more harmful, and although direct aspiration has a lower rate of first-pass recanalization, it seems appropriate to try direct aspiration as a first-line procedure. However, if the aspiration catheter cannot reach the clot, it is not useful or even risky to try aspiration alone. These results need to be confirmed by clinical studies.

Abstract Number ‐ 53: Endovascular therapy versus medical management for mild strokes due to medium and distal vessel occlusions

Introduction Distal and medium vessel occlusion (DMVO) strokes account for 25–40% of all acute ischemic strokes1 and are associated with long‐term disability in as many as 77% of patients2. Approximately one third of DMVO stroke patients have a low National Institute of Stroke Scale (NIHSS) (≤6)3. Multiple randomized controlled trials showed superiority of endovascular therapy (EVT) over best medical management (BMT) in patients presenting with proximal LVO involving the anterior circulation and NIHSS of &gt;64. The efficacy and safety of EVT for DMVO patients is uncertain, especially in patients with low NIHSS. A better understanding of this issue is important because many patients with DMVO and low NIHSS scores suffer disabling deficits while procedural risk are increased due to the target vessels’ small caliber, tortuosity, and thinner walls. We conducted a retrospective single center study to compare clinical and safety outcomes of DMVO patients with NIHSS ≤ 6 that were treated with EVT versus BMT. Methods We retrospectively analyzed consecutive patients with acute mild (NIHSS ≤ 6) DMVO stroke that presented between January 2018 and December 2021. We defined DMVO stroke as stroke caused by an occlusion of the M2‐4 segments of the MCA, A2‐3 segments of the ACA, P1‐2 segments of the PCA. Outcomes of interest were the NIHSS at day one and at discharge, the change in NIHSS from admission to discharge (ΔNIHSS) and the mRS at 90‐days. Safety outcomes were clinical deterioration, defined as an increase in the NIHSS by 4 or more points and the occurrence of symptomatic intracranial hemorrhage (sICH), defined as any type of ICH causing an increase in the NIHSS by 4 or more points. Results Overall, we included 80 subjects that fulfilled our study criteria. Of these, 41 were treated with BMT and 39 were selected to undergo EVT. Clinical characteristics of subjects selected for BMT versus EVT were overall similar except for more frequent diabetes (p = 0.035) and antiplatelet use (p = 0.045) as well as less frequent anticoagulation (p = 0.019) in the BMT group. Moreover, subjects selected for EVT had a lower pre‐stroke mRS (p = 0.025) and a lower ASPECT score on the admission head CT (p = 0.044). Overall, there was no statistical difference between NIHSS at day 1 (p = 0.654), NIHSS at discharge (p = 0.244), and ΔNIHSS from Day 0 to Day 1 (p = 0.08). There was further no difference in the discharge (p = 0.895) and 3‐month (p = 0.957) mRS between groups. Regarding safety outcomes, there was no difference in the number of all types of ICHs combined between the two groups (p = 0.229) and there was no difference in the number of patients who had clinical deterioration (p = 0.258). Conclusions Our analysis shows that in patients who present with mild DMVO strokes, early and 3‐month clinical outcomes were comparable between EVT and BMT groups. Moreover, risk of intracranial hemorrhage, clinical deterioration, and death were similar between groups. Nevertheless, given the low number of subjects, our analysis did not reach statistical significance and further large‐scale studies are required to clarify efficacy and safety of EVT versus BMT in DMVO patients with low clinical deficit severity

Abstract Number: LBA16 Does Intracranial Hemorrhage Associated with Tenecteplase Occur Exclusively Within the Stroke Burden?

Introduction As IV tenecteplase (TNK) is becoming an alternative to IV alteplase in acute ischemic stroke (AIS), establishing the incidence of intracranial hemorrhage (ICH) complications is important. Given the higher fibrin specificity of TNK as compared to alteplase, our aim was to distinguish hemorrhage within the stroke burden versus spontaneous ICH in patients with AIS with TNK‐associated ICH. Methods Retrospective chart review of patients presenting from February 2020 to January 2022 with anterior circulation AIS to our comprehensive stroke center who received TNK was performed to evaluate for associated ICH. ECASS‐3 criteria was used to define hemorrhagic transformation and ICH score was used for primary, spontaneous ICH. Fisher exact test statistic was used to evaluate for significant differences in ASPECTS score, medium versus versus large vessel occlusion, angiographic recanalization, IV eptifibatide use, pre‐morbid antiplatelet use, and association with symptomatic versus asymptomatic hemorrhage. A benchmark less than 5% symptomatic ICH incidence was set based on historical alteplase rates within our network. Social science statistics software was used for data analysis. Results Out of 77 subjects who received TNK, 20.7% (n = 16) developed ICH, 9.1% (n = 7) of which were symptomatic ICH with a temporally‐related increase in NIHSS of at least 4 or greater. Seven subjects (43.75%) were male. Mean age was 73.38 (95% CI 65.92, 80.83). Median initial NIHSS was 16, 95% CI [11.74, 21.51]. Median ASPECTS was 9, 95% CI [8.74, 9.89]. Two subjects developed spontaneous, primary ICH (n = 1 symptomatic ICH, n = 1 non‐symptomatic ICH) in the absence of hemorrhagic transformation of ischemic stroke. No significant difference between subjects with asymptomatic hemorrhage versus symptomatic hemorrhage was found when comparing ASPECTS &gt; = 7 versus &lt; 7 (Fisher value = 1), angiographic recanalization (Fisher value = 1), use of IV eptifibatide (Fisher value = 1), pre‐morbid antiplatelet use (Fisher value = 0.13), or medium vessel occlusion (Fisher value = ‐0.63). Conclusions Expected rates of hemorrhagic transformation were higher in tenecteplase than our historical benchmark rate for alteplase. Spontaneous hemorrhage unrelated to ischemic stroke area were seen in 2 subjects without known hematological disorders. Larger, prospective studies are needed to validate safety of tenecteplase in real world settings.