Thrombectomy for distal medium vessel occlusion with a new generation of Stentretriever (Tigertriever 13)

Pretreatment predictors of very poor clinical outcomes in medium vessel occlusion stroke patients treated with mechanical thrombectomy

BACKGROUND

Acute ischemic stroke (AIS) from primary medium vessel occlusions (MeVO) is a prevalent condition associated with substantial morbidity and mortality. Despite the common use of mechanical thrombectomy (MT) in AIS, predictors of poor outcomes in MeVO remain poorly characterized.

METHODS

In this prospectively collected, retrospectively reviewed, multicenter, multinational study, data from the MAD-MT (Multicenter Analysis of primary Distal medium vessel occlusions: effect of Mechanical Thrombectomy) registry were analyzed. The study included 1568 patients from 37 academic centers across North America, Asia, and Europe, treated with MT, with or without intravenous tissue plasminogen activator (IVtPA), between September 2017 and July 2021.

RESULTS

Among the 1568 patients, 347 (22.2%) experienced very poor outcomes (modified Rankin score (mRS), 5-6). Key predictors of poor outcomes were advanced age (odds ratio (OR): 1.03; 95% confidence interval (CI): 1.02 to 1.04; p < 0.001), higher baseline National Institutes of Health Stroke Scale (NIHSS) scores (OR: 1.07; 95% CI: 1.05 to 1.10; p < 0.001), pre-operative glucose levels (OR: 1.01; 95% CI: 1.00 to 1.02; p < 0.001), and a baseline mRS of 4 (OR: 2.69; 95% CI: 1.25 to 5.82; p = 0.011). The multivariable model demonstrated good predictive accuracy with an area under the receiver-operating characteristic (ROC) curve of 0.76.

CONCLUSIONS

This study demonstrates that advanced age, higher NIHSS scores, elevated pre-stroke mRS, and pre-operative glucose levels significantly predict very poor outcomes in AIS-MeVO patients who received MT. These findings highlight the importance of a comprehensive risk assessment in primary MeVO patients for personalized treatment strategies. However, they also suggest a need for cautious patient selection for endovascular thrombectomy. Further prospective studies are needed to confirm these findings and explore targeted therapeutic interventions.

Mechanical thrombectomy failure in anterior and posterior circulation stroke: current results from a high-volume comprehensive center

BACKGROUND

Mechanical thrombectomy (MT) is an established therapy for acute ischemic stroke (AIS), but recanalization is not always achieved. Common reasons are inadequate removal at the thrombus site and difficulties with the access route. In order to identify risk factors for MT failure we conducted a retrospective study on a high-volume comprehensive stroke center.

METHODS

Evaluation of 552 thrombectomies (2019-23; anterior and posterior circulation, direct aspiration +/- stent retriever [SR]). MT failures (= modified Thrombolysis in Cerebral Infarction score 0 or 1) were analyzed for age, sex, pre- and post-MT modified Rankin Scale, bridging intravenous thrombolysis (IVT), occlusion site (anterior / posterior circulation, proximal / distal), the Kaesmacher classification and time trend results.

RESULTS

MT failure occurred in 56 patients (10.1%; median age 76; 53.6% female). Nineteen (33.9%) patients received IVT (p = 0.326). Logistic regression analysis did not show a significant association of age, sex or occlusion site with MT failure (p = 0.165, p = 0.738, p = 0.838). Distal MT generally demonstrated lower success rates (p < 0.01). According to the Kaesmacher classification SR failure was the most frequent cause of MT failure (category 2B: 48%, p < 0.001). Time trend analysis suggests improving recanalization rates in the further course (4 times in year-on-year comparison; p < 0.01).

CONCLUSION

MT failure occurs in AIS treatment, even in high-volume centers and occurs more frequently in distal occlusions. Improvements in device technology, particularly SR, and ongoing refinements in access route selection offer the prospect of better outcomes in the future.

The Vecta 46 intermediate catheter for mechanical thrombectomy of distal medium vessel occlusions: A single-center experience

INTRODUCTION

With emerging evidence supporting the clinical efficacy and safety of mechanical thrombectomy (MT) for distal medium vessel occlusions (DMVOs), MT devices specifically designed to navigate through smaller caliber and more delicate tortuous distal cerebrovasculature are required. This study describes our single-center experience using the AXS Vecta 46 intermediate catheter for first-line thromboaspiration of DMVOs.

METHODS

We identified all patients who underwent MT using the Vecta 46 for first-line thromboaspiration for primary or secondary DMVOs. We collected baseline clinical data, angiographic and clinical outcomes, as well as procedural complications. The primary outcome in question was the rate of successful recanalization, which was defined as a modified Thrombolysis in Cerebral Infarction score of ≥2b.

RESULTS

We identified 43 patients who underwent MT using the Vecta 46 catheter for thromboaspiration of 54 DMVOs. Intervened vessels included the M2 (23/54), M3 (19/54), and M4 (6/54) branches of the middle cerebral artery, A2 (1/54), A3 (1/54), and A4 (1/54) branches of the anterior cerebral artery, and P1 (1/54), P2 (1/54), and P4 (1/54) branches of the posterior cerebral artery. The median number of passes for primary DMVOs was 2 (IQR: 1-3) and 1 (IQR: 1-1.25) for secondary DMVOs. The rate of successful recanalization was 100% (18/18) for primary DMVOs and 80.6% (29/36) for secondary DMVOs. First-pass effect (FPE) was noted in 55.6% (30/54) of all primary and secondary DMVO cases. Improved short-term clinical outcomes were observed in both the primary (National Institute of Health Stroke Scale [NIHSS] shift: -5 [IQR: -14.25 to -0.25]) and secondary (NIHSS shift: -5 [IQR: -10 to -2]) DMVO groups. A total of six patients died during their hospitalization, though none were deemed procedural-related.

CONCLUSIONS

Our study demonstrates the safety and efficacy of the Vecta 46 intermediate catheter for thromboaspiration of both primary and secondary DMVOs, achieving high rates of successful recanalization and FPE.

High Hypoperfusion Intensity Ratio Is Independently Associated with Very Poor Outcomes in Large Ischemic Core Stroke

BACKGROUND

Recent advances have highlighted the efficacy of endovascular thrombectomy (EVT) in patients with large ischemic core stroke, yet a significant portion still experience very poor outcomes, defined as a 90-day modified Rankin Score (mRS) of 5-6. This study aims to investigate the hypoperfusion intensity ratio (HIR) as a prognostic imaging parameter for these outcomes.

METHODS

In a multicenter retrospective cohort study, data from consecutive patients undergoing EVT for acute ischemic stroke with large vessel occlusion (AIS-LVO) at two comprehensive stroke centers were analyzed. The study included patients with an Alberta Stroke Program Early CT Score (ASPECTS) of 5 or less and utilized pretreatment perfusion imaging to calculate HIR. The primary outcome was very poor outcomes (90 days mRS 5-6).

RESULTS

Among 102 patients included, 59 (57.8%) had very poor outcome (90 days mRS 5-6). Multivariable logistic regression analysis adjusting for multiple covariates including admission National Institutes of Health Stroke Scale (NIHSS) and EVT revealed that higher admission NIHSS (adjusted odds ratio [aOR] 1.224, 95% CI 1.089-1.374, p = 0.001) and HIR (aOR per 0.1 incremental change, 1.34, 95% CI 1.02-1.82, P = 0.042) were independently associated with very poor outcomes.

CONCLUSION

This study demonstrates that admission NIHSS and HIR are independently associated with very poor outcome (90 days mRS 5-6) in patients with large ischemic core strokes. These findings highlight the importance of collateral status and perfusion imaging in predicting outcomes in this patient population, suggesting a potential role for HIR in the triage and management of large core stroke patients.

Multicenter evaluation of mechanical thrombectomy for distal medium vessel occlusions with National Institute of Health Stroke Scale Scores ≥ 6 and ≤ 6

BACKGROUND

While mechanical thrombectomy is considered standard of care for large vessel occlusions, scientific evidence to support treatment for distal and medium vessel occlusions remains scarce.

PURPOSE

To evaluate feasibility, safety, and outcomes in patients with low National Institute of Health Stroke Scale scores undergoing mechanical thrombectomy for treatment of distal medium vessel occlusions.

MATERIALS AND METHODS

Retrospective data review and analysis of prospectively maintained databases at 41 academic centers in North America, Asia, and Europe between January 2017 and January 2022. Characteristics and outcomes were compared between groups with low stroke scale score (≤ 6) versus and higher stroke scale scores (> 6). Propensity score matching using the optimal pair matching method and 1:1 ratio was performed.

RESULTS

Data were collected on a total of 1068 patients. After propensity score matching, there were a total of 676 patients included in the final analysis, with 338 patients in each group. High successful reperfusion rates were seen in both groups, 90.2% in ≤ 6 and 88.7% in the > 6 stroke scale groups. The frequency of excellent and good functional outcome was seen more common in low versus higher stroke scale score patients (64.5% and 81.1% versus 39.3% and 58.6%, respectively). The 90-day mortality rate observed in the ≤ 6 stroke scale group was 5.3% versus 13.3% in the > 6 stroke scale group.

CONCLUSION

Mechanical thrombectomy in distal and medium vessel occlusions, specifically in patients with low stroke scale scores is feasible, though it may not necessarily improve outcomes over IVT.

Combining the deployment of only the distal basket segment of the EMBOTRAP III and an aspiration catheter for M2 occlusions: the ONE-SEG technique

Background

Endovascular therapy (EVT) for distal medium vessel occlusions requires prioritizing effectiveness and safety. We developed a technique combining the deployment of only the distal basket segment of the EMBOTRAP III and an aspiration catheter (AC) for M2 occlusions, called the "ONE-SEG technique," and evaluated its clinical and technical impacts.

Methods

This was a retrospective review of 30 consecutive patients with M2 segment middle cerebral artery occlusion treated using the ONE-SEG technique. This method involves deploying the EMBOTRAP III through a microcatheter in only one segment and guiding the AC to the M2 origin or distal M1. The rates of final-pass expanded thrombolysis in cerebral infarction (eTICI) scores of 2c/3 or 2b/2c/3, safety (symptomatic intracranial hemorrhage [sICH]), and clinical outcomes (modified Rankin Scale [mRS] score 0-2, 0-3 at 90 days, and mortality at 90 days) were evaluated.

Results

Of the 30 cases, 36.7% were female, and the mean age was 75.6 ± 11.0 years. The ONE-SEG technique was used for 17 cases (56.7%, median NIHSS 10 [5-15.5]) with primary M2 occlusion and 13 cases (43.3%, median NIHSS 20 [14-22.5]) with secondary M2 occlusion after proximal thrombus removal. The successful final reperfusion rate (eTICI 2b/2c/3) was 90% overall (27/30 cases). One case (3.3%) developed sICH with secondary M2 occlusion. At 3 months, mRS scores 0-2 were seen in 64.7% of patients with primary M2 occlusion (11/17 cases) and in 23.1% (3/13 cases) with secondary M2 occlusion.

Conclusion

EVT using the ONE-SEG technique appears to be safe and effective for M2 occlusion.

Optimizing thrombectomy in medium vessel occlusion: Focus on vessel diameter

OBJECTIVES

Mechanical thrombectomy for medium vessel occlusion (MeVO) is a challenging field with limited results. In this study, we aimed at evaluating the efficacy and safety of a procedural strategy beginning with occluded vessel diameter measurement and matched aspiration catheter selection.

MATERIALS AND METHODS

We retrospectively analyzed all sequentially treated patients by mechanical thrombectomy at two comprehensive stroke centers between May 2020 and April 2023, focusing on the occluded vessel diameter. We included patients who underwent thrombectomy for MeVO based on the matching strategy (a procedural approach involving vessel diameter assessment, matching aspiration catheter selection, and firm clot engagement with or without a stent retriever). We evaluated efficacy and safety using the modified Thrombolysis in the Cerebral Infarction Scale (mTICI) and intracranial hemorrhage (ICH) and procedure-related complications.

RESULTS

Seventy patients fulfilled the final inclusion criteria. The median occluded vessel diameter was 1.71 mm. We achieved mTICI 2b/2c/3 in 82.9% and mTICI 2c/3 in 51.4% of the cases and did not observe any symptomatic ICH. We detected asymptomatic subarachnoid hemorrhage (SAH) in 24.3% of the cases, that is, 5.6%, 20.0%, and 45.5% in the vessel diameter groups ≥2.0, 1.5-2.0, and ≤1.5 mm, respectively. The SAH incidence was significantly higher in narrower vessel groups. The occluded vessel diameter and the contact method with clots predicted clinical outcomes.

CONCLUSIONS

Matching strategy-based thrombectomy yields acceptable efficiency and safety results. In narrower vessels, it is optimal to engage matched aspiration catheters and clots without the assistance of conventional stent retrievers.

Pretreatment CTP Collateral Parameters Predict Good Outcomes in Successfully Recanalized Middle Cerebral Artery Distal Medium Vessel Occlusions

BACKGROUND/PURPOSE

Distal medium vessel occlusions (DMVOs) account for a large percentage of vessel occlusions resulting in acute ischemic stroke (AIS) with disabling symptoms. We aim to assess whether pretreatment quantitative CTP collateral status (CS) parameters can serve as imaging biomarkers for good clinical outcomes prediction in successfully recanalized middle cerebral artery (MCA) DMVOs.

METHODS

We performed a retrospective analysis of consecutive patients with AIS secondary to primary MCA-DMVOs who were successfully recanalized by mechanical thrombectomy (MT) defined as modified thrombolysis in cerebral infarction (mTICI) 2b, 2c, or 3. We evaluated the association between the CBV index and HIR independently with good clinical outcomes (modified Rankin score 0-2) using Spearman rank correlation, logistic regression, and ROC analyses.

RESULTS

From 22 August 2018 to 18 October 2022 8/22/2018 to 10/18/2022, 60 consecutive patients met our inclusion criteria (mean age 71.2 ± 13.9 years old [mean ± SD], 35 female). The CBV index (r = -0.693, p < 0.001) and HIR (0.687, p < 0.001) strongly correlated with 90-day mRS. A CBV index ≥ 0.7 (odds ratio, OR, 2.27, range 6.94-21.23 [OR] 2.27 [6.94-21.23], p = 0.001)) and lower likelihood of prior stroke (0.13 [0.33-0.86]), p = 0.024)) were independently associated with good outcomes. The ROC analysis demonstrated good performance of the CBV index in predicting good 90-day mRS (AUC 0.73, p = 0.003) with a threshold of 0.7 for optimal sensitivity (71% [52.0-85.8%]) and specificity (76% [54.9-90.6%]). The HIR also demonstrated adequate performance in predicting good 90-day mRS (AUC 0.77, p = 0.001) with a threshold of 0.3 for optimal sensitivity (64.5% [45.4-80.8%]) and specificity (76.0% [54.9-90.6%]).

CONCLUSION

A CBV index ≥ 0.7 may be independently associated with good clinical outcomes in our cohort of AIS caused by MCA-DMVOs that were successfully treated with MT. Furthermore, a HIR < 0.3 is also associated with good clinical outcomes. This is the first study of which we are aware to identify a CBV index threshold for MCA-DMVOs.

Endovascular treatment of distal medium vessel occlusions using microcatheter aspiration thrombectomy

BACKGROUND AND PURPOSE

Recent studies suggest that endovascular treatment (EVT) in distal medium vessel occlusion (DMVO) stroke is beneficial even beyond middle cerebral artery (MCA) - M2 segment. However, data about aspiration thrombectomy of DMVOs is scarce since common state-of-the-art aspiration catheters are usually too large for small distal intracranial arteries. We report our initial experiences using the microcatheter aspiration thrombectomy (MAT) technique as frontline therapy for acute DMVOs in the MCA territory.

METHODS

We retrospectively analyzed all acute ischemic stroke (AIS) patients that underwent MAT of a primary or secondary DMVO in the M3 or M4 segment between January 2019 and October 2021. Recanalization rates, procedural safety and outcome data were recorded.

RESULTS

MAT of acute M3 and M4 occlusions was performed in 19 patients with AIS. Six had isolated DMVO strokes, 13 had secondary DMVOs during EVT of a proximal large vessel occlusion. Successful revascularization to DMVO TICI ≥ 2b was achieved in 58% (11/19) with a single pass in all of them. The median National Institutes of Health Strokes Scale (NIHSS) score at admission and discharge was 12 and 3, respectively. 68% (13/19) of the patients had a good clinical outcome at discharge (modified Rankin Scale 0-2). No symptomatic complications related to MAT occurred.

CONCLUSIONS

MAT of DMVOs in the MCA territory is technically feasible and effective. Compared to stent retriever-based thrombectomy in DMVOs the hemorrhagic complication rate appears notably lower. Further studies are needed to validate the benefit of mechanical thrombectomy in the distal intracranial vasculature.

Prognostic value of recanalization attempts in endovascular therapy for M2 segment middle cerebral artery occlusions

BACKGROUND

There is growing evidence suggesting efficacy of endovascular therapy for M2 occlusions of the middle cerebral artery. More than one recanalization attempt is often required to achieve successful reperfusion in M2 occlusions, associated with general concerns about the safety of multiple maneuvers in these medium vessel occlusions.

AIM

The aim of this study was to investigate the association between the number of recanalization attempts and functional outcomes in M2 occlusions in comparison with large vessel occlusions (LVO).

METHODS

Retrospective multicenter cohort study of patients who underwent endovascular therapy for primary M2 occlusions. Patients were enrolled in the German Stroke Registry at 1 of 25 comprehensive stroke centers between 2015 and 2021. The study cohort was subdivided into patients with unsuccessful reperfusion (mTICI 0-2a) and successful reperfusion (mTICI 2b-3) at first, second, third, fourth, or ⩾fifth recanalization attempt. Primary outcome was 90-day functional independence defined as modified Rankin Scale score of 0-2. Safety outcome was the occurrence of symptomatic intracranial hemorrhage. Internal carotid artery or M1 occlusions were defined as LVO and served as comparison group.

RESULTS

A total of 1078 patients with M2 occlusion were included. Successful reperfusion was observed in 87.1% and 90-day functional independence in 51.9%. The rate of functional independence decreased gradually with increasing number of recanalization attempts (p < 0.001). In both M2 occlusions and LVO, successful reperfusion within three attempts was associated with greater odds of functional independence, while success at ⩾fourth attempt was not. Patients with ⩾4 attempts exhibited higher rates of symptomatic intracranial hemorrhage in M2 occlusions (6.5% vs 2.7%, p = 0.02) and LVO (7.2% vs 3.5%, p < 0.001).

CONCLUSION

This study suggests a clinical benefit of successful reperfusion within three recanalization attempts in endovascular therapy for M2 occlusions, which was similar in LVO. Our findings reduce concerns about the risk-benefit ratio of multiple attempts in M2 medium vessel occlusions.

DATA ACCESS STATEMENT

The data that support the findings of this study are available on reasonable request after approval of the German Stroke Registry (GSR) steering committee.

CLINICAL TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov Identifier: NCT03356392.

The Management of Persistent Distal Occlusions after Mechanical Thrombectomy and Thrombolysis: An Inter- and Intrarater Agreement Study

BACKGROUND AND PURPOSE

The best management of patients with persistent distal occlusion after mechanical thrombectomy with or without IV thrombolysis remains unknown. We sought to evaluate the variability and agreement in decision-making for persistent distal occlusions.

MATERIALS AND METHODS

A portfolio of 60 cases was sent to clinicians with varying backgrounds and experience. Responders were asked whether they considered conservative management or rescue therapy (stent retriever, aspiration, or intra-arterial thrombolytics) a treatment option as well as their willingness to enroll patients in a randomized trial. Agreement was assessed using κ statistics.

RESULTS

The electronic survey was answered by 31 physicians (8 vascular neurologists and 23 interventional neuroradiologists). Decisions for rescue therapies were more frequent (n = 1116/1860, 60%) than for conservative management (n = 744/1860, 40%; P < .001). Interrater agreement regarding the final management decision was "slight" (κ = 0.12; 95% CI, 0.09-0.14) and did not improve when subgroups of clinicians were studied according to background, experience, and specialty or when cases were grouped according to the level of occlusion. On delayed re-questioning, 23 of 29 respondents (79.3%) disagreed with themselves on at least 20% of cases. Respondents were willing to offer trial participation in 1295 of 1860 (69.6%) cases.

CONCLUSIONS

Individuals did not agree regarding the best management of patients with persistent distal occlusion after mechanical thrombectomy and IV thrombolysis. There is sufficient uncertainty to justify a dedicated randomized trial.

Penumbral cooling in ischemic stroke with intraarterial, intravenous or active conductive head cooling: A thermal modeling study

In ischemic stroke, selectively cooling the ischemic penumbra might lead to neuroprotection while avoiding systemic complications. Because penumbral tissue has reduced cerebral blood flow and in vivo brain temperature measurement remains challenging, the effect of different methods of therapeutic hypothermia on penumbral temperature are unknown. We used the COMSOL Multiphysics® software to model a range of cases of therapeutic hypothermia in ischemic stroke. Four ischemic stroke models were developed with ischemic core and/or penumbra volumes between 33-300 mL. Four experiments were performed on each model, including no cooling, and intraarterial, intravenous, and active conductive head cooling. The steady-state temperature of the non-ischemic brain, ischemic penumbra, and ischemic core without cooling was 37.3 °C, 37.5-37.8 °C, and 38.9-39.4 °C respectively. Intraarterial, intravenous and active conductive head cooling reduced non-ischemic brain temperature by 4.3 °C, 2.1 °C, and 0.7-0.8 °C respectively. Intraarterial, intravenous and head cooling reduced the temperature of the ischemic penumbra by 3.9-4.3 °C, 1.9-2.1 °C, and 1.2-3.4 °C respectively. Active conductive head cooling was the only method to selectively reduce penumbral temperature. Clinical studies that measure brain temperature in ischemic stroke patients undergoing therapeutic hypothermia are required to validate these hypothesis-generating findings.

Safety and efficacy of endovascular thrombectomy for primary and secondary MeVO

BACKGROUND

Medium-vessel occlusions (MeVO) are emerging as a new target for endovascular treatment (EVT). Primary MeVO occur de novo, while secondary MeVO arise from large vessel occlusion (LVO) through clot migration or fragmentation - spontaneously, following intravenous thrombolysis or EVT. We aimed to evaluate efficacy and safety of EVT in primary and EVT-induced secondary MeVO.

METHODS

Retrospective single-center study on consecutive EVT-treated acute ischemic stroke, from 2019-to-2021. We considered: (1) exclusive-LVO, patients with LVO and - in case of residual distal occlusion - no rescue endovascular procedure; (2) primary MeVO: initial A2, A3, M2 non-dominant, M3, P2, P3 occlusions; (3) EVT-induced secondary MeVO, presenting LVO with subsequent (treated) EVT-induced MeVO. We compared (univariable/multivariable logistic regression) EVT efficacy (eTICI≥2b, 3-month modified Rankin Scale [mRS] 0-2) and safety (EVT-complications [vessel dissection, perforation, persistent-SAH], symptomatic ICH) in all MeVO versus exclusive-LVO, primary MeVO versus exclusive-LVO, EVT-induced secondary MeVO versus exclusive-LVO and EVT-induced secondary MeVO versus primary MeVO.

RESULTS

We included 335 patients: 221 (66.0 %) exclusive-LVO and 114 (34.0 %) MeVO (55 [48.2 %] primary, 59 [51.8 %] secondary). Compared to exclusive-LVO, primary MeVO had higher rates of EVT complications (aOR 3.77 [95%CI 1.58-9.00],p=0.003), lower rates of eTICI≥2b (aOR 0.32 [95%CI 0.12-0.88],p=0.027) and mRS 0-2 (aOR 0.28 [95%CI 0.13-0.63],p=0.002). EVT-induced secondary MeVO had no major differences in efficacy and safety outcomes compared to exclusive-LVO, but a better mRS 0-2 (aOR 8.00 [95%CI 2.12-30.17],p=0.002) compared to primary MeVO.

CONCLUSIONS

Primary and EVT-induced secondary MeVO showed different safety/efficacy EVT-related profiles. Dedicated randomized data are needed to identify the best acute reperfusion strategy in the two categories.

Mechanical thrombectomy for the treatment of primary and secondary distal medium-vessel occlusion stroke: systematic review and meta-analysis

BACKGROUND

There is limited evidence on the indication and role of mechanical thrombectomy (MT) in patients with distal medium-vessel occlusions (DMVOs). The aim of this systematic review and meta-analysis was to evaluate all the evidence available on the efficacy and safety of MT techniques (stent retriever, aspiration) in primary and secondary DMVOs.

METHODS

Five databases were searched from inception to January 2023 for studies of MT in primary and secondary DMVOs. Outcomes of interest included favorable functional outcome (90-day modified Rankin scale (mRS) 0-2), successful reperfusion (modified Thrombolysis in Cerebral Infarction (mTICI) 2b-3), symptomatic intracerebral hemorrhage (sICH), and 90-day mortality. Prespecified subgroup meta-analyses according to the specific MT technique and to the vascular territory (distal M2-M5, A2-A5, P2-P5) were also performed.

RESULTS

A total of 29 studies with 1262 patients were included. For primary DMVOs (n=971 patients), pooled rates of successful reperfusion, favorable outcome, 90-day mortality and sICH were 84% (95% confidence interval (CI) 76 to 90%), 64% (95% CI 54 to 72%), 12% (95% CI 8 to 18%), and 6% (95% CI 4 to 10%), respectively. For secondary DMVOs (n=291 patients), pooled rates of successful reperfusion, favorable outcome, 90-day mortality and sICH were 82% (95% CI 73 to 88%), 54% (95% CI 39 to 69%), 11% (95% CI 5 to 20%), and 3% (95% CI 1 to 9%), respectively. Subgroup analyses by MT technique and by vascular territory showed no differences in primary and secondary DMVOs.

CONCLUSION

Our findings suggest that MT using aspiration or stent retriever techniques appears to be effective and safe in primary and secondary DMVOs. However, given the level of evidence of our results, further confirmation in well-designed randomized controlled trials is needed.

Endovascular therapy for acute ischemic stroke with distal medium vessel occlusion: a systematic review and meta-analysis

AIMS

Endovascular therapy (EVT) for distal medium vessel occlusions (DMVOs) is a potential frontier of acute ischemic stroke (AIS) treatment, but its efficacy against best medical therapy (BMT) remains unknown. We performed a systematic review and meta-analysis evaluating the efficacy and safety of EVT versus BMT in primary DMVO.

METHODS

We systematically searched PubMed, Cochrane Library and Embase, from inception to August 14, 2022, for studies comparing EVT with BMT in DMVO-AIS. We adopted the Distal Thrombectomy Summit Group's definition of DMVO. Efficacy outcomes were functional independence (90-day modified Rankin Scale (mRS) 0-2) and excellent functional outcomes (90-day mRS 0-1). Safety outcomes were symptomatic intracranial hemorrhage (sICH) and 90-day mortality.

RESULTS

Fourteen observational and two randomized-controlled studies were included, with 1202 patients receiving EVT and 1267 receiving BMT. After trim-and-fill correction, EVT achieved significantly better odds of functional independence than BMT (adjusted OR 1.61, 95% CI 1.06 to 2.43). There were no significant differences in overall excellent functional outcomes (OR 1.23, 95% CI 0.88 to 1.71), sICH (OR 1.44, 95% CI 0.78 to 2.66), and mortality (OR 1.03, 95% CI 0.73 to 1.45). Stratified by EVT method, mechanical thrombectomy±intra-arterial thrombolysis achieved more excellent functional outcomes than BMT (OR 1.59, 95% CI 1.13 to 2.23). In mild strokes (National Institutes of Health Stroke Scale score <6), EVT caused significantly more sICH (OR 6.30, 95% CI 1.55 to 25.64).

CONCLUSIONS

EVT shows promising efficacy benefit over BMT for primary DMVO-AIS. Further randomized controlled trials are necessary to evaluate the efficacy and safety of EVT in DMVO-AIS.

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

BACKGROUND AND PURPOSE

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) >6 seconds 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).

METHODS

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 5 days of symptom onset. Diagnostic performance between CTP thresholds and FIV was assessed in the successfully and unsuccessfully recanalized groups.

RESULTS

Fifty-five patients met our inclusion criteria (32 female [58.2%], 68.0 ± 12.1 years 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 >10 seconds (area under the receiver operating characteristic curve = .875, p = .001).

CONCLUSION

In AIS patients with DMVOs, longer Tmax delays than Tmax  > 6 seconds, most notably, Tmax  > 10 seconds, best predict FIV in unsuccessfully recanalized patients. No CTP threshold reliably predicts FIV in the successfully recanalized group nor significantly outperformed rCBF < 30%.

Contemporary Methods for Detection and Intervention of Distal Medium and Small Vessel Occlusions

The efficacy of using mechanical thrombectomy for proximal large vessel occlusions has been demonstrated in multiple large-scale trials and has further raised the question of its potential utility for distal medium and small vessel occlusions (DMSVOs). Their longer, more tortuous course and smaller corresponding vascular territories render a significant challenge for detection and intervention. The aim of this study is to provide a comprehensive overview of the current imaging and endovascular intervention options for DMSVOs and review the current works in the literature. Compared with traditional computed tomography angiography (CTA) and CT perfusion, recent advances such as multiphase CTA and maps derived from the time-to-maximum parameter coupled with artificial intelligence have demonstrated increased sensitivity for the detection of DMSVOs. Furthermore, newer generations of mini stent retrievers and thromboaspiration devices have allowed for the access and navigation of smaller and more fragile distal arteries. Preliminary studies have suggested that mechanical thrombectomy using this newer generation of devices is both safe and feasible in distal medium-sized vessels, such as M2. However, endovascular intervention utilizing such contemporary methods and devices must be balanced at the discretion of operator experience and favorable vascular anatomy. Further large-scale multicenter clinical trials are warranted to elucidate the indications for as well as to strengthen the safety and efficacy of this approach.

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

Background

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.

Methods

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).

Results

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.

Conclusions

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.

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

Introduction

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.

Methods

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.

Results

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.

Conclusion

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.

Distal medium vessel occlusions in acute ischaemic stroke - Stent retriever versus direct aspiration: A systematic review and meta-analysis

BACKGROUND

Acute ischaemic stroke due to distal medium vessel occlusion (AIS-DMVO) causes significant morbidity. Endovascular thrombectomy advancement has made treating AIS-DMVO with stent retrievers (SR) and aspiration catheters (AC) possible, however the optimal technique remains unknown. We performed a systematic review and meta-analysis to investigate the efficacy and safety of SR use compared to purely AC use in patients with AIS-DMVO.

METHODS

We systematically searched PubMed, Cochrane Library and EMBASE, from inception to 2nd September 2022, for studies comparing SR or primary combined (SR/PC) against AC in AIS-DMVO. We adopted the Distal Thrombectomy Summit Group's definition of DMVO. Efficacy outcomes were functional independence (modified Rankin Scale (mRS) 0-2 at 90 days), first pass effect (modified Thrombolysis in Cerebral Infarction scale (mTICI) 2c-3 or expanded Thrombolysis in Cerebral Infarction scale (eTICI) 2c-3 at first pass), successful final recanalisation (mTICI or eTICI 2b-3), and excellent final recanalisation (mTICI or eTICI 2c-3). Safety outcomes were symptomatic intracranial haemorrhage (sICH) and 90-day mortality.

RESULTS

12 cohort studies and 1 randomised-controlled trial were included, involving 1881 patients with 1274 receiving SR/PC and 607 receiving AC only. SR/PC achieved higher odds of functional independence (odds ratio (OR) 1.33, 95% confidence interval (CI) 1.06-1.67) and lower odds of mortality (OR 0.69, 95% CI 0.50-0.94) than AC. Odds of successful/excellent recanalisation and sICH were similar between both groups. Stratified to compare only SR and only AC, the use of only SR, achieved significantly higher odds of successful recanalisation as compared to only AC (OR 1.80, 95% CI 1.17-2.78).

CONCLUSION

There is potential for efficacy and safety benefits in SR/PC use as compared to AC only in AIS-DMVO. Further trials are necessary to validate the efficacy and safety of SR use in AIS-DMVO.

Treatment of Acute Stroke: Current Practices and Future Horizons

PURPOSE

This review will discuss revascularization of acute ischemic stroke (AIS), discussing the concept of the ischemic penumbra and how thrombolysis and thrombectomy take advantage of it.

SUMMARY

The goal of AIS revascularization is to rescue the ischemic penumbra and the approach to has gone from a time-based to tissue-based approach. Patients must be carefully selected for thrombolysis, which traditionally was limited to those whose last known normal time (LKNT) was known and within 4.5 h. However, newer imaging techniques involving MRI and CT perfusion (CTP) can select patients for thrombolysis whose LKNT is unknown. Alteplase, or tPA, is still the agent of choice for thrombolysis in patients with AIS but tenecteplase (TNK) may be just as effective and more efficient to use. Endovascular thrombectomy (EVT) has shown considerable efficacy for treating large-vessel occlusions and using CTP, patients can be selected for hours after symptom-onset if viable tissue remains. Further research is underway to determine if EVT can be used for medium vessel occlusions and for basilar artery thromboses as well as to determine whether an "EVT-alone" strategy is superior to "tPA + EVT" strategy.

Comparing Tigertriever 13 to other thrombectomy devices for distal medium vessel occlusion: A systematic review and meta-analysis

BACKGROUND

There is limited evidence on the optimal endovascular strategy for treatment of distal medium-vessel occlusions (DMVO). The low-profile Tigertriever 13 stent-triever shows early promise as an adaptable device that can navigate the distal vasculature without increasing complication risk in DMVO.

METHODS

Using Nested Knowledge, we screened literature for RCTs and cohort studies on the endovascular treatment of DMVO. The primary outcome was reperfusion success, as measured by thrombolysis in cerebral infarction (TICI) ≥ 2b and secondary outcomes included rate of symptomatic intracranial hemorrhage (sICH), mortality at 90 days, and modified Rankin scale (mRS) scores 0-2 at 90 days. A random-effects model was used to compute pooled prevalence rates and their corresponding 95% confidence intervals (CI).

RESULTS

Eleven studies with 1402 patients, 167 patients treated by Tigertriever 13 and 1235 patients treated by other devices, were included in the meta-analysis. The rate of reperfusion success was similar in patients treated by Tigertriever 13 (83.2% [95% CI: 71.5-96.7%]) versus other devices (81.6% [95% CI: 75.3-88.4%], p > 0.05). The rate of sICH was also similar in patients treated by Tigertriever 13 (7.2% [95% CI: 4.1-12.5%]) versus other devices (6.9% [95% CI: 5.5-8.8%]). There was significant heterogeneity in the reporting of mortality and mRS.

CONCLUSIONS

Tigertriever 13 had similar rates of reperfusion success and sICH as other devices used for the treatment of DMVO. Heterogeneity in data element reporting prevented further analyses. Further studies evaluating Tigertriever 13 and other potential devices in DMVO should attempt to harmonize data element reporting.

[Neurothrombectomy 2022-Extension of indications and technical innovations]

For advanced territorial ischemia numerous retrospective and prospective studies have shown a positive effect of mechanical thrombectomy (MT) compared to best medicinal treatment alone. For patients with minor stroke (NIHSS < 6) there is currently a lack of evidence for MT. Appropriate study protocols must differentiate between patients with large vessel occlusion with disproportionately mild symptoms and more distal vascular occlusion and therefore correspondingly fewer clinical symptoms. The role of intravenous lysis treatment before MT as bridging lysis also currently retains its general recommendation, as large studies could not show a uniform noninferiority of MT alone. In addition, the use of intra-arterial lysis after successful MT offers a promising approach, which still needs to be evaluated. Novel aspiration catheters and stent-retrievers as well as competing thrombectomy techniques can be compared by the first pass effect, the successful recanalization with only one attempt at thrombectomy. Contact aspiration and stent-retriever thrombectomy under aspiration are equivalent and established thrombectomy procedures. For the latter, several detailed maneuver tactics are described for improvement of thrombectomy success. Also, in retrospective studies the combination with a balloon-guided catheter promises a further improvement of recanalization results. In the case of failure of supra-aortic vessel probing with inguinal access, radial access and direct carotid puncture are alternative access routes. Recent studies on ICA stenting with tandem occlusions showed a benefit of stents without an increased risk for symptomatic intracranial hemorrhage. The retrograde approach, to first treat the intracranial vessel occlusion and then the carotid stenosis, seems to be advantageous.

The Anch'Or Harpoon Technique With a Manually Expandable Stentretriever (Tigertriever 13), a Technical Note

Background and purpose

Stent and balloon anchor techniques have been described to obtain distal support and straighten catheter loops, stabilize microcatheters in giant aneurysms, or access distal tortuous anatomy during thrombectomy. These techniques require catheterization of distal arteries with a microcatheter but tortuosity and length issues may render it challenging, precluding the distal unsheathing of a classical auto-expandable stentretriever with the anchor technique.

Methods

Therefore, we developed the so-called Anch'Or Harpoon Technique using a manually expandable stent retriever, the Tigertriever 13 (Rapid Medical, Yoqneam, Israel). Here, the stent retriever is not unsheathed but pushed out of a microcatheter, and then advanced as far as possible before manual opening.

Results and conclusion

This technique may be used in 2 different situations. First, in the case of vessel tortuosity if the microcatheter can't be advanced as far as the physician wants: the Tigertriever 13 could be delivered through the microcatheter without having to unsheathe it, and be advanced and opened distally to its microcatheter to establish a stable anchor prior to advancing the guiding, intermediate, and micro-catheters (Anchor technique). The second situation is when distal occlusions lead to length issues; the microcatheter may be too short to cross a distal clot: the Tigertriever 13 could then be pushed out of the microcatheter, and be used to cross a sub-occlusive clot as it has a soft shaped distal tip and the physician has a visual on the artery beyond the sub-occlusion. Then, the Tigertriever would be manually expanded through the clot and retrieved (Harpoon technique) to obtain a recanalization.

Early Neurological Improvement Predicts Clinical Outcome After Thrombectomy for Distal Medium Vessel Occlusions

Background and Purpose

Good clinical outcome predictors have been established in mechanical thrombectomy (MT) for acute ischemic stroke (AIS) caused by large vessel occlusion (LVO). An early neurological improvement (ENI), defined as a reduction of ≥8 on the National Institutes of Health Stroke Scale (NIHSS), compared with the baseline score or an NIHSS of 0 or 1 at 24 h after MT, is a strong predictor of favorable outcome. We aimed to study the impact of ENI after MT for distal medium vessel occlusions (DMVO).

Methods

We retrospectively analyzed the data of consecutive patients who underwent MT for a primary DMVO in one large academic center. We compared clinical outcomes between patients with DMVO stratified by ENI. Multivariate analyses were performed to determine the impact of ENI on good 90-day outcome (modified Rankin scale of 0–2) and identify factors contributing to ENI.

Results

Between January 2018 and January 2021, 61 patients underwent an MT for an AIS with a primary DMVO. An ENI was seen in 24 (39%) patients (ENI+). Outcomes were significantly better in ENI+ patients, with 83% achieving a good outcome at 3 months vs. 43% for patients without ENI (ENI–; p = 0.019). ENI was an independent predictive factor of good clinical outcome even after adjusting for potential confounding factors [odds ratio 12.49 (1.49–105.01), p = 0.020]. The use of intravenous tissue plasminogen activator [IVtPA; Odds-ratio 6.59 (1.82–23.89), p = 0.004] was a positive predictor of ENI.

Conclusion

ENI at day 1 following MT for DMVO stroke is a strong independent predictor of good to excellent 3-month clinical outcome.

Predictors of Good Clinical Outcome after Thrombectomy for Distal Medium Vessel Occlusions

OBJECTIVE

Good clinical outcome predictors have been emphasized in mechanical thrombectomy (MT) for acute ischemic stroke (AIS) with large vessel occlusion (LVO). MT for distal, medium vessel occlusions (DMVO) is still debated. We sought to assess the factors associated with clinical outcome after MT for DMVO.

METHODS

We retrospectively analyzed the data of consecutive patients who underwent MT for a primary DMVO in one large academic center and aimed to identify the baseline clinical, imaging and MT factors associated with good clinical outcome (defined as modified Rankin scale [mRS] of 0-2) at 3 months.

RESULTS

Between January 2018 and January 2021, 61 patients underwent a MT for an AIS with a primary DMVO. Overall, good clinical outcome was achieved in 56% (34/61) of our patients. In multivariate analysis, an older age (ODDS ratio 0.89 [0.83-0.96], p=0.003), longer puncture to recanalization time (ODDS ratio 0.97 [0.93-0.99], p=0.033), and higher baseline core volume (ODDS ratio 0.84 [0.75-0.94], p=0.003) decreased the probability of good clinical outcomes, while a final complete (or near-) recanalization (mTICI 2c-3) increased the probability of good outcome (ODDS ratio 14.19 [1.99-101.4], p=0.008).

CONCLUSION

An older age, a longer puncture to recanalization time and a higher baseline core volume decreased the probability of good clinical outcomes, while successful recanalization (mTICI 2c-3) was associated with better outcomes after MT for DMVO.