The Trevo XP 3×20 mm retriever (‘Baby Trevo’) for the treatment of distal intracranial occlusions

Predictors of tissue infarction from distal emboli after mechanical thrombectomy

BACKGROUND

Distal embolization after endovascular thrombectomy (EVT) is common. We aimed to determine factors associated with tissue infarction in the territories of distal emboli.

METHODS

This is a retrospective cohort study of consecutive patients with anterior circulation large vessel occlusions who underwent EVT from 2015 to 2021. Patients with Thrombolysis In Cerebral Infarction (TICI) 2b reperfusion and follow-up imaging were identified. Baseline characteristics, procedural details, and imaging findings were reviewed. Primary outcome was categorized according to the occurrence of infarction at the territory of distal embolus on follow-up diffusion-weighted imaging MRI.

RESULTS

Of 156 subjects, 97 (62%) had at least one infarction in the territories at risk. Hypertension was significantly more prevalent in the infarct group (83% vs 53%, P=0.001). General anesthesia was more commonly used in the infarct group (60% vs 43%, P=0.037). The median number of distal emboli and diameter of the occluded vessel were similar. After adjusting for confounders, hypertension (aOR 4.73, 95% CI 1.81 to 13.25, P=0.002), higher blood glucose (aOR 1.01, 95% CI 1.00 to 1.03, P=0.023), and general anesthesia (aOR 2.75, 95% CI 1.15 to 6.84, P=0.025) were independently associated with infarction. The presence of angiographic leptomeningeal collaterals predicted tissue survival (aOR 0.13, 95% CI 0.05 to 0.33, P<0.001). 90-day modified Rankin scale (mRS) scores were worse for the infarction patients (mRS 0-2: infarct, 39% vs 55%, P=0.046).

CONCLUSIONS

Nearly 40% of patients with TICI 2b had no tissue infarction in the territory of a distal embolus. The association of infarction with hypertension and general anesthesia suggests late or post-procedural blood pressure management could be a modifiable factor. Patients with poor leptomeningeal collaterals or hyperglycemia may benefit from further attempts at revascularization.

Suction thrombectomy of distal medium vessel occlusion using microcatheter during mechanical thrombectomy for acute ischemic stroke: A case series

While mechanical thrombectomy is known to be effective for distal medium vessel occlusion (DMVO) as well as large vessel occlusion, tortuous DMVO are predisposed to vessel injury during stent retriever thrombectomy. Furthermore, getting access to the thrombus may be difficult during suction thrombectomy using a dedicated suction catheter. Most studies describe DMVO treatment using stent retrievers and dedicated suction catheters, but there are limited studies reporting DMVO treated with suction thrombectomy using a microcatheter. Herein, we describe three cases of DMVO treated with suction thrombectomy that was performed using a microcatheter and subsequently showed good results. Therefore, suction thrombectomy using a microcatheter is a viable alternative treatment for tortuous DMVO.

Reliability assessment of distal occlusion eTICI scoring

BACKGROUND

The eThrombolysis in Cerebral Infarction (eTICI) score has been validated in proximal large artery occlusion (pLAOs). Despite the growing number of distal medium vessel occlusions (DMVOs) mechanical thrombectomies (MT) and the widespread utilization of the eTICI scoring system, its reliability and standardization for more distal occlusions have not been validated. We aim to evaluate the interrater reliability of eTICI scores in primary DMVOs.

METHODS

This was a retrospective analysis of a prospectively maintained database for consecutive patients with pLAO and DMVO MT at a single comprehensive stroke center from 2015 to 2022. Two fellowship-trained neurointerventionalists blindly/independently assessed digital subtraction angiograms for final eTICI, followed by consensus reads for discrepancies.

RESULTS

59 DMVO of 2248 thrombectomies [M3:29(50%)/M4:1(2%)/A1:3(5%)/A2:12(22%)/A3: 5(9%)/P1:7(12%)/P2:1(2%)] and 124 pLAOs of 308 thrombectomies [i-ICA:13(11%)/MCA-M1: 111(90%)] were included. The distribution of final eTICI scores was comparable between pLAO vs DMVOs (p = 0.82). The pLAO final eTICI score assessment between two readers demonstrated moderate reliability with a kappa0.77 (95%CI: 0.67-0.88), while the DMVO eTICI score assessment exhibited almost-perfect agreement with kappa 0.94 (95%CI: 0.90-0.99). The agreement between the consensus read and the original report in DMVOs was 0.86 (95% CI: 0.71-1.00) while for pLAO it was 0.83(95% CI: 0.76-0.90). The performance of eTICI was comparable amongst different DMVO territories as well as for distal vs. very distal occlusions.

CONCLUSION

eTICI score exhibited comparable performance for DMVO as compared to pLAO strokes. Further studies investigating DMVO eTICI grading and clinical outcomes are warranted.

Mechanical thrombectomy with Embolus Retriever with Interlinked Cages device for medium vessel occlusions: First pass results and safety profile

BACKGROUND

Reperfusion of medium vessel occlusions is correlated with good outcomes. However, optimal techniques and medical devices are still unclear. In this study, we sought to evaluate the safety and efficacy of mechanical thrombectomy with Embolus Retriever with Interlinked Cages (ERIC™) retrieval device in patients with acute ischemic stroke due to distal medium vessel occlusions.

METHODS

A retrospective review of the prospectively collected mechanical thrombectomy database revealed 50 patients who had fulfilled the inclusion criteria. The data collected includes clinical patient characteristics, procedural measures, timestamps at each stage, and patient outcomes. Intravenous thrombolytics application, pre- and post-intervention imaging findings, device-related adverse events and any type of intracranial hemorrhage were recorded.

RESULTS

There were 25 men (50%) and 25 women (50%) with a median of 67 years (interquartile range (IQR) 41-84). Median presenting NIHSS was 14 (IQR, 3-23). First pass rates were: eTICI3 in 16 cases (32%), eTICI-2c in eight cases (16%), eTICI-2B67 in nine cases (10%), eTICI2B50 in three cases (6%) and mTICI 0-2A in 18 cases (36%). Final recanalization rate of mTICI 2b-3 was 90% and 2c-3 was 70%.

CONCLUSION

In conclusion, the ERIC thrombectomy device offers a high rate of first-pass success along with a favorable safety profile. Larger series and multi-center studies are needed for further investigation.

Distal Medium Vessel Occlusion Strokes: Understanding the Present and Paving the Way for a Better Future

Distal medium vessel occlusions (DMVOs) are thought to cause as many as 25% to 40% of all acute ischemic strokes and may result in substantial disability amongst survivors. Although intravenous thrombolysis (IVT) is more effective for distal than proximal vessel occlusions, the overall efficacy of IVT remains limited in DMVO with less than 50% of patients achieving reperfusion and about 1/3 to 1/4 of the patients failing to achieve functional independence. Data regarding mechanical thrombectomy (MT) among these patients remains limited. The smaller, thinner, and more tortuous vessels involved in DMVO are presumably associated with higher procedural risks whereas a lower benefit might be expected given the smaller amount of tissue territory at risk. Recent advances in technology have shown promising results in endovascular treatment of DMVOs with room for future improvement. In this review, we discuss some of the key technical and clinical considerations in DMVO treatment including the anatomical and clinical terminology, diagnostic modalities, the role of IVT and MT, existing technology, and technical challenges as well as the contemporary evidence and future treatment directions.

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.

Endovascular treatment for M3 occlusions

INTRODUCTION

Endovascular treatment (ET) is a beneficial treatment for M1-2 occlusions of the middle cerebral artery. Mortality and disability rates are high if large vessel occlusions are not treated. While these rates are lower in M3 occlusions, important branch blockages can lead to disability. Endovascular treatment of small vessel occlusions is difficult, and there are no studies on the effectiveness of endovascular treatment for M3 occlusions. Accordingly, in this study, our aim was to assess the feasibility, safety, and preliminary efficacy of endovascular therapy for M3 occlusions.

METHODS

This study involved a retrospective analysis of a prospectively collected from two centres for acute ischemic stroke of the anterior system between July 2015 and April 2020. Demographic, radiologic, procedural and outcome variables were collected for patients who underwent endovascular therapy for acute ischemic stroke of the anterior system.

RESULTS

Complete or near complete reperfusion (mTICI 2b-3) of the M3 occlusion was achieved in 15 cases (38.5%). Complete (mTICI 3) reperfusion was achieved in 24 cases (61.5%). Twenty-six patients were treated for primary M3 occlusion, while 13 patients with M3 occlusion were treated as a rescue strategy after successful treatment of a proximal greater vascular occlusion. Complete or near complete reperfusion (mTICI 2b-3) of primary occlusion was achieved in eight cases (30.8%), and complete (mTICI 3) reperfusion was achieved in 18 cases (69.2%). In addition, complete or near complete reperfusion (mTICI 2b-3) of rescue M3 occlusion was achieved in seven cases (%53.8), while complete (mTICI 3) reperfusion was achieved in six cases (46.2%). Only one patient with primary M3 occlusion had ICH due to extravasation. The patient's neurological examination one month later was normal.

CONCLUSIONS

This retrospective study demonstrates that endovascular treatment of M3 occlusions is safe, effective and reliable.

Post-diffusion and perfusion magnetic resonance imaging of emboli to distal territories after endovascular thrombectomy

BACKGROUND AND PURPOSE

This study aimed to investigate the clinical outcomes of emboli to distal territories (EDT) after aspiration thrombectomy in patients with acute anterior circulation occlusion.

MATERIALS AND METHODS

From January 2016 to December 2022, all eligible patients who underwent endovascular treatment (EVT) due to acute anterior circulation occlusion were retrospectively reviewed. During this period, patients with EDT after EVT underwent magnetic resonance (MR) perfusion with angiography and diffusion-weighted imaging within 12 hours from recanalization. Hypoperfusion was defined as a Tmax value > 6-second volume.

RESULTS

Of the 104 eligible patients (65 males, median age 74 years), 79 (76.0 %; 2a: 19, 2b: 55, 2c: 5) had hypoperfusion on perfusion MR (PWI). Complete mismatch on diffusion-weighted imaging (DWI) of the hypoperfusion area was significantly higher in patients with successful recanalization than in patients with incomplete recanalization (58.3 % vs. 31.6 %, p = 0.0437). Of the 79 patients with hypoperfusion, 24 had EDT in the M2, 39 in the M3, and 16 in the M4. Complete mismatch on DWI and PWI was significantly higher in patients with a distal EDT (M3 or M4) than in patients with an M2 EDT (65.8 % vs. 20.8 %, p < 0.001).

CONCLUSIONS

EDT to the M3 or more distal branches after EVT had a higher rate of complete DWI-PWI mismatch on early follow-up MRI than EDT to M2.

Comparison of 4 mm-sized and 3 mm-sized Stent Retrievers in Mechanical Thrombectomy for M2 Occlusion

INTRODUCTION

A stent retriever (SR) is widely used in mechanical thrombectomy (MT) for M2 segment occlusion. However, the suitable size of SR in M2 occlusion remains unclear. Therefore, we aimed to compare 4 mm-sized SR with 3 mm-sized SR in M2 occlusion.

METHODS

Patients who underwent MT with SR for M2 occlusion were dichotomized into 4×20 mm SR and 3×20 mm SR groups. Then, 1:1 propensity score matching was performed. The M2 segment was divided into proximal and distal segments according to the occlusion site. Subgroup analysis was then performed for each cohort.

RESULTS

A total of 111 patients were enrolled, with 4×20 mm SR and 3×20 mm SR applied in 72 (64.9%) and 39 (35.1%) cases, respectively. In propensity score matching, mean number of stent passages for reperfusion was significantly lower in the 4×20 mm SR group than in the 3×20 mm SR group (1.5 ± 0.8 vs. 2.1 ± 1.1; p = 0.004). First-pass reperfusion (FPR) was more highly achieved in the 4×20 mm SR group than in the 3×20 mm SR group (52.6% vs. 42.1%; p = 0.007). In both proximal and distal occlusion cohorts, the 4 mm SR group showed lower mean number of SR passage (p = 0.004 and p = 0.003, respectively) and higher FPR rate than the 3 mm SR group (p = 0.003 and p = 0.007, respectively).

CONCLUSION

In MT for M2 occlusion, 4×20 mm SR enables an effective procedure with lesser SR passage for reperfusion and a higher rate of FPR than 3×20 mm SR.

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.

Effectiveness of the preventive administration of vasoactive amines in counterbalancing significant patient blood pressure drops following nimodipine administration during mechanical thrombectomy procedures

BACKGROUND

Focal vasospasm (FV) of the occluded vessel can occur during the endovascular treatment of acute ischemic stroke (AIS). Nimodipine is commonly used to treat vasospasm and can play a role in distinguishing it from artery narrowing due to iatrogenic dissection or residual clot. However, nimodipine administration can result in arterial hypotension and subsequent enlargement of the ischemic core.

OBJECTIVE

To assess the efficacy of preventive and continuous vasoactive amine infusion to counterbalance nimodipine-induced hypotension.

METHODS

We reviewed data from a prospective registry of patients treated for AIS between January 2019 and January 2022 who were administered nimodipine. All patients were equipped with an arterial cannula for invasive blood pressure measurement and given vasoactive amines preemptively before general anesthesia and throughout the procedure. Data obtained from invasive monitoring of mean arterial blood pressure (MABP) in a time-lapse of 25 min before and after nimodipine administration were analyzed.

RESULTS

MABP significantly decreased after nimodipine administration but remained within the recommended range (81.79 ± 0.49 mmHg). Nimodipine was effective in reducing FV caused by stent retriever passage in 76.3% of cases. Furthermore, it proved valuable in diagnosing iatrogenic dissection (9.2%), residual clot (10.5%), or intracranial stenosis (4%).

CONCLUSIONS

Infusion of vasoactive amines effectively counteracted the intraarterial nimodipine effect, thus avoiding frank arterial hypotension during endovascular treatment. Nimodipine has been useful in differentiating the diagnosis of FV resulting from mechanical thrombectomy and other potential causes, such as iatrogenic dissection or residual clot.

Thrombectomy of Mild Stroke : An Analysis of the Nationwide Registry of the German Society for Neuroradiology

PURPOSE

Whether patients presenting with mild stroke (NIHSS at admission < 6) should be treated with mechanical thrombectomy (MT) is the subject of an ongoing debate. This retrospective study based on large-scale clinical data aims to identify factors associated with favorable outcome (FO) in patients with mild stroke.

METHODS

A total of 761 patients with mild stroke enrolled between 1 January 2020 and 31 December 2020 in the Quality Registry of the German Society for Neuroradiology were analyzed. The FO was defined as stable or improved NIHSS at discharge vs. admission. Descriptive statistics and multivariable logistic regression analyses were performed to identify factors associated with FO. Furthermore, a subgroup analysis of mild stroke based on distal vessel occlusion was conducted.

RESULTS

In this study 610 patients had FO with a median NIHSS at discharge of 1 (interquartile range, IQR, 0-2) and 151 had an unfavorable outcome (UO) with median NIHSS at discharge of 10 (IQR 13). Patients with FO had a slightly higher NIHSS at admission (4 vs. 3, p < 0.001), lower mTICI 0 (2.7% vs. 14.2%, p < 0.001), higher mTICI 3 (61.3% vs. 34.5%, p < 0.001) and a lower number of passes (1 vs. 2, p < 0.001). No statistically significant difference was observed for MT-related adverse events. Multivariable logistic regression suggested that NIHSS at admission (adjusted odds ratio (aOR) = 1.28, 95% confidence interval (CI) = 1.10-1.48), mTICI 2b (aOR = 5.44, CI = 2.06-15.03), mTICI 2c (aOR = 10.81, CI = 3.65-34.07) and mTICI 3 (aOR = 11.56, CI = 4.49-31.10) as well as number of passes (aOR 0.76, CI = 0.66-0.88) were significantly associated with FO. No MT-related adverse events were observed for distal vessel occlusions.

CONCLUSION

The FO in patients with mild stroke undergoing MT was associated with successful recanalization. No significant differences between patients with FO and UO were found for MT-related adverse events, suggesting that MT complications have no significant effects on the outcome of these patients. MT might improve the prognosis also in patients with mild stroke based on distal vessel occlusions without significantly increasing the risk of adverse events.

Middle Cerebral Artery M2 Thrombectomy: Safety and Technical Considerations in the German Stroke Registry (GSR)

There is ongoing debate concerning the safety and efficacy of various mechanical thrombectomy (MT) approaches for M2 occlusions. We compared these for MT in M2 versus M1 occlusions. Subgroup analyses of different technical approaches within the M2 MT cohort were also performed. Patients were included from the German Stroke Registry (GSR), a multicenter registry of consecutive MT patients. Primary outcomes were reperfusion success events. Secondary outcomes were early clinical improvement (improvement in NIHSS score > 4) and independent survival at 90 days (mRS 0−2). Out of 3804 patients, 2689 presented with M1 (71%) and 1115 with isolated M2 occlusions (29%). The mean age was 76 (CI 65−82) and 77 (CI 66−83) years, respectively. Except for baseline NIHSS (15 (CI 10−18) vs. 11 (CI 6−16), p < 0.001) and ASPECTS (9 (CI 7−10) vs. 9 (CI 8−10, p < 0.001), baseline demographics were balanced. Apart from a more frequent use of dedicated small vessel stent retrievers (svSR) in M2 (17.4% vs. 3.0; p < 0.001), intraprocedural aspects were balanced. There was no difference in ICH at 24 h (11%; p = 1.0), adverse events (14.4% vs. 18.1%; p = 0.63), clinical improvement (62.5% vs. 61.4 %; p = 0.57), mortality (26.9% vs. 22.9%; p = 0.23). In M2 MT, conventional stent retriever (cSR) achieved higher rates of mTICI3 (54.0% vs. 37.7−42.0%; p < 0.001), requiring more MT-maneuvers (7, CI 2−8) vs. 2 (CI 2−7)/(CI 2−2); p < 0.001) and without impact on efficacy and outcome. Real-life MT in M2 can be performed with equal safety and efficacy as in M1 occlusions. Different recanalization techniques including the use of svSR did not result in significant differences regarding safety, efficacy and outcome.

Thrombectomy of symptomatic isolated occlusions of posterior cerebral arteries in segment P1 and P2 in acute stroke treatment

BACKGROUND

Interventional stroke treatments for occlusions of the posterior circulation are established procedures. However, there are limited data on the treatment of isolated symptomatic P1 and P2 occlusions, which we have examined in this study.

PURPOSE

To investigate the mechanical thrombectomy of distal posterior occlusions.

MATERIAL AND METHODS

Retrospectively, data from patients with isolated P1 and P2 occlusions treated with MT were evaluated. Successful reperfusions have been defined as modified thrombolysis in cerebral infarct (mTICI) Grade 2b-3. A good clinical outcome was defined as a 90-day modified Rankin score 0-2.

RESULTS

All 79 treated patients were primarily aspirated. Stent retrievers were used secondarily in nine patients. Successful reperfusion was achieved in 95% of patients. Of the patients, 57% had a favorable clinical outcome after 90 days.

CONCLUSION

Mechanical thrombectomy with first line aspiration of symptomatic P1 and P2 occlusions is a safe and effective procedure.

Patient and procedure selection for mechanical thrombectomy: Toward personalized medicine and the role of artificial intelligence

Mechanical thrombectomy (MT) for ischemic stroke due to large vessel occlusion is standard of care. Evidence-based guidelines on eligibility for MT have been outlined and evidence to extend the treatment benefit to more patients, particularly those at the extreme ends of a stroke clinical severity spectrum, is currently awaited. As patient selection continues to be explored, there is growing focus on procedure selection including the tools and techniques of thrombectomy and associated outcomes. Artificial intelligence (AI) has been instrumental in the area of patient selection for MT with a role in diagnosis and delivery of acute stroke care. Machine learning algorithms have been developed to detect cerebral ischemia and early infarct core, presence of large vessel occlusion, and perfusion deficit in acute ischemic stroke. Several available deep learning AI applications provide ready visualization and interpretation of cervical and cerebral arteries. Further enhancement of AI techniques to potentially include automated vessel probe tools in suspected large vessel occlusions is proposed. Value of AI may be extended to assist in procedure selection including both the tools and technique of thrombectomy. Delivering personalized medicine is the wave of the future and tailoring the MT treatment to a stroke patient is in line with this trend.

Clinical protocol of the ischemic stroke patients treatment

Today in Ukraine there is no single standardized protocol for the treatment of patients in the acute period of ischemic stroke using modern methods of diagnosis and treatment, which include thrombolytic therapy and endovascular treatment. This protocol was created and implemented in Scientific-practical Center of endovascular neuroradiology, NAMS of Ukraine and is based on the latest recommendations of AHA/ASA and ESO, as well as registers of patients with ischemic stroke. The main purpose of this publication is the creation and implementation of «instructions» for the diagnosis and selection of objective tactics for treating patients in the acute period of ischemic stroke.

Endovascular administration of magnetized nanocarriers targeting brain delivery after stroke

The increasing use of mechanical thrombectomy in stroke management has opened the window to local intraarterial brain delivery of therapeutic agents. In this context, the use of nanomedicine could further improve the delivery of new treatments for specific brain targeting, tracking and guidance. In this study we take advantage of this new endovascular approach to deliver biocompatible poly(D-L-lactic-co-glycolic acid) (PLGA) nanocapsules functionalized with superparamagnetic iron oxide nanoparticles and Cy7.5 for magnetic targeting, magnetic resonance and fluorescent molecular imaging. A complete biodistribution study in naïve (n = 59) and ischemic (n = 51) mice receiving intravenous or intraarterial nanocapsules, with two different magnet devices and imaged from 30 min to 48 h, showed an extraordinary advantage of the intraarterial route for brain delivery with a specific improvement in cortical targeting when using a magnetic device in both control and ischemic conditions. Safety was evaluated in ischemic mice (n = 69) showing no signs of systemic toxicity nor increasing mortality, infarct lesions or hemorrhages. In conclusion, the challenging brain delivery of therapeutic nanomaterials could be efficiently and safely overcome with a controlled endovascular administration and magnetic targeting, which could be considered in the context of endovascular interventions for the delivery of multiple treatments for stroke.

Risks of Undersizing Stent Retriever Length Relative to Thrombus Length in Patients with Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Results regarding the association of thrombus length, stent retriever length, and recanalization success in patients with acute ischemic stroke are inconsistent. We hypothesized that the ratio of thrombus length to stent retriever length may be of particular relevance.

MATERIALS AND METHODS

Patients with acute ischemic stroke undergoing stent retriever thrombectomy at our institution between January 2010 and December 2018 were reviewed retrospectively. Thrombus length was assessed by measuring the susceptibility vessel sign on SWI using a 1.5T or 3T MR imaging scanner. Multivariable logistic regression models were used to determine the association between thrombus length, stent retriever length, and thrombus length/stent retriever length ratio with first-pass recanalization, overall recanalization, and embolization in new territories. Results are shown as adjusted ORs with 95% CIs. Additional mediation analyses were performed to test for indirect effects on first-pass recanalization and overall recanalization success.

RESULTS

The main analysis included 418 patients (mean age, 74.9 years). Increasing stent retriever length was associated with first-pass recanalization. Decreasing thrombus length and lower thrombus length/stent retriever length ratios were associated with first-pass recanalization and overall recanalization. Thrombus length and stent retriever length showed no association with first-pass recanalization or overall recanalization once thrombus length/stent retriever length ratio was factored in, while thrombus length/stent retriever length ratio remained a significant factor in both models (adjusted OR, 0.316 [95% CI, 0.112-0.892]; P = .030 and adjusted OR, = 0.366 [95% CI, 0.194-0.689]; P = .002). Mediation analyses showed that decreasing thrombus length and increasing stent retriever length had a significant indirect effect on first-pass recanalization mediated through thrombus length/stent retriever length ratio. The only parameter associated with embolization in new territories was an increasing thrombus length/stent retriever length ratio (adjusted OR, 5.079 [95% CI, 1.332-19.362]; P = .017).

CONCLUSIONS

Information about thrombus and stent length is more valuable when combined. High thrombus length/stent retriever length ratios, which may raise the risk of unsuccessful recanalization and embolization in new territories, should be avoided by adapting stent retriever selection to thrombus length whenever possible.

The Tigertriever 13 for mechanical thrombectomy in distal and medium intracranial vessel occlusions

PURPOSE

To report our two-center initial experience using the Tigertriever 13 in the treatment of acute stroke of distal, medium vessel occlusions (DMVO).

METHODS

We performed a retrospective analysis of all patients treated by mechanical thrombectomy using the Tigertriever 13 device (a manually expandable low profile stent retriever) due to an acute DMVO. Locations included the anterior, middle, and posterior cerebral artery in the A2 and A3, the M3 and M4, and the P2 or P3 segment and the superior cerebellar artery.

RESULTS

Forty-three patients with 45 DMVOs underwent MTE using the Tigertriever 13 with the intention-to-treat approach between May 2019 and December 2020. After a median of two thrombectomy maneuvers, the successful recanalization rate (mTICI 2b-3) was 84.4% (38/45) with a first pass effect of 26.7% (12/45). The rate of symptomatic intracranial hemorrhages (sICH) and subarachnoid hemorrhages (SAH) was 7.0% (3/43) and 14.0% (6/43), respectively. At discharge, 53.5% (23/43) of the patients had a favorable clinical outcome (mRS 0-2).

CONCLUSION

Mechanical thrombectomy in DMVOs using the Tigertriever 13 leads to high recanalization rates. The incidence of mostly asymptomatic hemorrhagic events appears higher compared to MTE procedures in LVOs. Further studies will help to identify anatomic and clinical criteria to define a guideline for MTE in DMVOs.

Initial Experience Performing Mechanical Thrombectomy With the CatchView Mini Device for Distal M2 Segment Middle Cerebral Artery Occlusions

Background: Mechanical thrombectomy (MT) has become the standard of care for acute ischemic stroke due to large vessel occlusion; however, its safety and efficacy in patients with distal strokes remains unclear. In this study, we investigated the safety and efficacy of MT for distal middle cerebral artery (MCA) occlusions using the CatchView Mini (CVM; Balt, Montmorency, France).

Methods: This was a prospective single-center analysis of patients with a single MCA-M2 occlusion treated with the CVM device. Consecutive patients were prospectively enrolled from October 2018 to March 2020. Efficacy outcomes included successful recanalization [modified Thrombolysis in Cerebral Infarction (mTICI) 2b/3], procedure times, and number of device passes. Clinical outcomes included National Institutes of Health Stroke Scale Score (NIHSS) at discharge, 90-day functional independence (modified Rankin Scale 0–2) and safety outcomes included hemorrhagic complications, and 90-day mortality.

Results: A total of 45 patients (mean age: 74.0 ± 12.6; 53.3% [24/45] female) were included in the study. Upon admission, 33.3% (15/45) of patients were mRS 3–5; and mean NIHSS was 13.2 ± 4.2 Mean time from symptom onset to final angiography was 250.0 ± 83.4 min with a mean intervention duration of 34.0 ± 12.6 min. The mean number of device passes was 1.8 ± 1.5 final mTICI 2b/3 was achieved in 91.1% (41/45) of patients. Eight hemorrhagic complications (17.8%, 8/34) occurred, none of which were symptomatic. At 90-days, 57.8% (26/45) patients were functionally independent and the rate of mortality was 15.6% (7/45).

Conclusions: The present analysis demonstrates a low risk profile and high recanalization success for patients with distal M2 occlusions treated with the CVM device.

[Border areas of thrombectomy]

Mechanical thrombectomy (MT) has become the standard procedure in the treatment of patients with acute ischemic stroke (AIS) due to occlusion of a large proximal cerebral artery of the anterior circulation. Nevertheless, according to the current guidelines large patient collectives are still excluded from this highly effective treatment method. Therefore, this article gives an overview of possible extensions of the indications for treatment with MT. For example, patients in the extended time window with distal occlusions, with large infarct cores and also for very old (90+ years) or young (0-17 years) patients. Furthermore, we discuss recent developments in the interventional treatment of stroke, such as new triage concepts or the question whether an additional intravenous thrombolysis is necessary in patients with MT. We conclude with our own estimations for the discussed indications for treatment based on our clinical experience and the current literature.

Adjunctive Intra-arterial Thrombolysis in Endovascular Thrombectomy: A Systematic Review and Meta-analysis

OBJECTIVE

To evaluate the safety and efficacy of intra-arterial thrombolysis (IAT) as an adjunct to endovascular thrombectomy (EVT) in ischemic stroke, we performed a systematic review and meta-analysis of the literature.

METHODS

Searches were performed using MEDLINE, Embase, and Cochrane databases for studies that compared EVT with EVT with adjunctive IAT (EVT + IAT). Safety outcomes included symptomatic intracerebral hemorrhage and mortality at 3 months. Efficacy outcomes included successful reperfusion (Thrombolysis in Cerebral Infarction score of 2b-3) and functional independence, defined as a modified Rankin Scale score of 0-2 at 3 months.

RESULTS

Five studies were identified that compared combined EVT + IAT (IA alteplase or urokinase) with EVT only and were included in the random-effects meta-analysis. There were 1693 EVT patients, including 269 patients treated with combined EVT + IAT and 1,424 patients receiving EVT only. Pooled analysis did not demonstrate any differences between EVT + IAT and EVT only in rates of symptomatic intracerebral hemorrhage (odds ratio [OR]: 0.61, 95% confidence interval [CI]: 0.20-1.85; p = 0.78), mortality (OR: 0.77, 95% CI: 0.54-1.10; p = 0.15), or successful reperfusion (OR: 1.05, 95% CI: 0.52-2.15; p = 0.89). There was a higher rate of functional independence in patients treated with EVT + IAT, although this was not statistically significant (OR: 1.34, 95% CI: 1.00-1.80; p = 0.053).

CONCLUSION

Adjunctive IAT appears to be safe. In specific situations, neurointerventionists may be justified in administering small doses of intra-arterial alteplase or urokinase as rescue therapy during EVT.

Subarachnoid Hemorrhage in Mechanical Thrombectomy for Acute Ischemic Stroke: Analysis of the STRATIS Registry, Systematic Review, and Meta-Analysis

Background: The indications for mechanical thrombectomy in acute ischemic stroke continue to broaden, leading neurointerventionalists to treat vessel occlusions at increasingly distal locations farther in time from stroke onset. Accessing these smaller vessels raises the concern of iatrogenic subarachnoid hemorrhage (SAH) owing to increasing complexity in device navigation and retrieval. This study aims to determine the prevalence of SAH following mechanical thrombectomy, associated predictors, and resulting functional outcomes using a multicenter registry and compare this with a systematic review and meta-analysis of the literature. Methods: Data from STRATIS (The Systematic Evaluation of Patients Treated with Neurothrombectomy Devices for Acute Ischemic Stroke) registry were analyzed dichotomized by the presence or absence of SAH after thrombectomy. Only patients with 24-h post-procedural neuroimaging were included (n = 841). Multivariable logistic regression was performed to identify significant predictors of SAH. A systematic review and random-effects meta-analysis was also conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) protocol. Results: The prevalence of post-thrombectomy SAH was 5.23% in STRATIS with 15.9% (1.84% overall) experiencing neurological decline. Distal location of vessel occlusion (OR 3.41 [95% CI: 1.75-6.63], p < 0.001) and more than 3 device passes (OR 1.34 [95% CI: 1.09-1.64], p = 0.01) were associated with a higher probability of SAH in contrast to a reduction with administration of intravenous tissue plasminogen activator (tPA) (OR 0.48 [95% CI: 0.26-0.89], p = 0.02). There was a trend toward a higher discharge NIHSS (8.3 ± 8.7 vs. 5.3 ± 6.6, p = 0.07) with a significantly reduced proportion achieving functional independence at 90 days (modified Rankin Score 0-2: 32.5% vs. 57.8%, p = 0.002) in SAH patients. Pooled analysis of 10,126 patients from 6 randomized controlled trials and 64 observational studies demonstrated a prevalence of 5.85% [95% CI: 4.51-7.34%, I ²: 85.2%]. Only location of vessel occlusion was significant for increased odds of SAH at distal sites (OR 2.89 [95% CI: 1.14, 7.35]). Conclusions: Iatrogenic SAH related to mechanical thrombectomy is more common with treatment of distally-situated occlusions and multiple device passes. While low in overall prevalence, its effect is not benign with fewer patients reaching post-procedural functional independence, particularly if symptomatic.

Blind Exchange With Mini-Pinning Technique Using the Tron Stent Retriever for Middle Cerebral Artery M2 Occlusion Thrombectomy in Acute Ischemic Stroke

Introduction: The usefulness of the blind exchange with mini-pinning (BEMP) technique has recently been reported for mechanical thrombectomy in patients with stroke owing to medium vessel occlusion (MeVO). The Tron stent retriever can be delivered and deployed through a 0.0165-inch microcatheter. This retriever has potential as an effective and safe treatment for acute ischemic stroke (AIS) due to occlusion of the M2 segment of the middle cerebral artery (MCA). Here, we report the outcomes of the BEMP technique using Tron stent retrievers for M2 occlusion thrombectomy.

Methods: Consecutive patients with AIS owing to M2 occlusion who underwent the BEMP technique using 2 × 15-mm or 4 × 20-mm Tron stent retrievers were included. The technique involves deploying a Tron stent retriever through a 0.0165-inch microcatheter, followed by microcatheter removal and blind navigation of a 3MAX or 4MAX aspiration catheter over the bare Tron delivery wire until the aspiration catheter reaches the clot. A Tron stent retriever is inserted into the aspiration catheter like a cork and subsequently pulled as a unit. We assessed procedural outcomes [first-pass expanded thrombolysis in cerebral infarction (eTICI) score 2c/3 and 2b/2c/3], safety outcomes [symptomatic intracranial hemorrhage (sICH)], and clinical outcomes (good outcome rate defined as modified Rankin Scale score 0–2 at 90 days and mortality at 90 days).

Results: Eighteen M2 vessels were treated in 15 patients (six female, median age: 80 years, and median National Institutes of Health Stroke Scale score: 18). The BEMP technique was performed successfully in all cases. Whether to use a 3MAX or 4MAX catheter was determined by considering one of the following target vessels: dominant, non-dominant, or co-dominant M2 (3MAX, n = 9; 4MAX, n = 9). The first-pass eTICI 2c/3 and 2b/2c/3 rates were 47 (7/15) and 60% (9/15), respectively; sICH was not observed. Seven patients (47%) achieved good outcomes, and one patient (7%) died within 90 days.

Conclusions: The Tron stent retriever was safely and effectively used in the BEMP technique for acute MCA M2 occlusion and can be combined with a 0.0165-inch microcatheter, which may be useful for treating MeVO, in general.

Mechanical Thrombectomy for Distal Occlusions: Efficacy, Functional and Safety Outcomes: Insight from the STAR Collaboration

BACKGROUND

Mechanical thrombectomy (MT) is the standard of care for the treatment of proximal anterior circulation large vessel occlusions. However, little is known about its efficacy and safety in the treatment of distal intracranial occlusions.

METHODS

This is a multicenter retrospective study of patients treated with MT at 15 comprehensive centers between January 2015 and December 2018. The study cohort was divided into 2 groups based on the location of occlusion (proximal vs. distal). Distal occlusion was defined as occlusion of M3 segment of the middle cerebral artery, any segment of the anterior cerebral artery, or any segment of the posterior cerebral artery. Only isolated distal occlusion was included. Good outcome was defined as 90-day modified Rankin scale score 0-2.

RESULTS

A total of 4710 patients were included in this study, of whom 189 (4%) had MT for distal occlusions. Compared with the proximal occlusion group, distal occlusion group had a higher rate of good outcome (45% vs. 36%; P = 0.03) and a lower rate of successful reperfusion (78% vs. 84%; P = 0.04). However, the differences did not retain significance in adjusted models. Otherwise there was no difference in the rate of hemorrhagic complications, mortality, or procedure-related complications between the 2 groups. Successful reperfusion, age, and admission stroke severity emerged as predictors of good functional outcome in the distal occlusion group.

CONCLUSIONS

Thrombectomies of distal vessels achieve high rate of successful reperfusion with similar safety profile to those in more proximal locations.

Expanding indications for endovascular thrombectomy-how to leave no patient behind

Endovascular thrombectomy (EVT) has become standard of care for large vessel occlusion strokes but current guidelines exclude a large proportion of patients from this highly effective treatment. This review therefore focuses on expanding indications for EVT in several borderline indications such as patients in the extended time window, patients with extensive signs of infarction on admission imaging, elderly patients and patients with pre-existing deficits. It also discusses the current knowledge on intravenous thrombolysis as an adjunct to EVT and EVT as primary therapy for distal vessel occlusions, for tandem occlusions, for basilar artery occlusions and in pediatric patients. We provide clear recommendations based on current guidelines and further literature.

Effectiveness of very low profile thrombectomy device in primary distal medium vessel occlusion, as rescue therapy after incomplete proximal recanalization or following iatrogenic thromboembolic events

Background

Recent progress with smaller retrievers has expanded the ability to reach distal brain arteries. We herein report recanalization, bleeding complications and short-term clinical outcomes with the smallest currently known low profile thrombectomy device in patients with primary or secondary distal medium vessel occlusion (DMVO).

Methods

We performed a retrospective analysis of 115 patients receiving mechanical thrombectomy (MT) in DMVO using the extended Thrombolysis in Cerebral Infarction (eTICI), European Cooperative Acute Stroke Study (ECASS) II classification, The National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) scores at admission and discharge to evaluate outcomes. Patients were stratified into three groups: (1) primary isolated distal occlusion (n=34), (2) secondary distal occlusion after MT of a proximal vessel occlusion (n=71), or (3) during endovascular treatment of aneurysms or arteriovenous malformations (AVMs) (n=10).

Results

Successful distal recanalization, defined as an eTICI score of 2b67, 2c and 3, was achieved in 74.7% (86/115) of patients. More specifically, it was 70.5% (24/34), 73.2% (52/71), and 100% (10/10) of primary DMVO, secondary DMVO after proximal MT, and rescue MT during aneurysm or AVM embolization, respectively. Symptomatic intraparenchymal bleeding occurred in 6.9% (eight patients). In-hospital mortality occurred in 18.1% (19/105) of patients with stroke. The most common cause of death was large infarct, old age, and therapy limitation.

Conclusion

Direct or rescue MT of DMVO using a very low profile thrombectomy device is associated with a high rate of successful recanalization and a reasonable rate of symptomatic hemorrhagic complication, despite a risk of 18.1% hospital mortality in elderly patients. Further trials are needed to confirm our results and assess long-term clinical outcomes.

Acute ischemic stroke endovascular therapy

Endovascular therapy (EVT) has become the standard treatment for large-vessel occlusion (LVO) acute ischemic stroke (AIS). EVT is now indicated in patients up to 24h from their last known well, provided that the patient meets specific clinical and imaging criteria. Improvements in thrombectomy devices, techniques, and operator experience have allowed successful EVT of ICA terminus, M1-MCA occlusions as well as proximal M2-MCA, basilar artery occlusions, and revascularization of tandem lesions. Mechanical thrombectomy failures still occur due to several factors, however, highlighting the need for further device and technical improvements. An ongoing debate exists regarding the need for pre-EVT thrombolytic agents, thrombectomy techniques, distal occlusions, anesthesia methods, the role of advanced neuroimaging, the treatment of patients with larger infarct core, and those presenting with milder stroke symptoms. Many of these questions are the subject of current or upcoming clinical trials. This review aims to provide an outline and discussion about the established recommendations and emerging topics regarding EVT for LVO AIS.

Endovascular therapy in the distal neurovascular territory: results of a large prospective registry

BACKGROUND

There is a paucity of data regarding mechanical thrombectomy (MT) in distal arterial occlusions (DAO). We aim to evaluate the safety and efficacy of MT in patients with DAO and compare their outcomes with proximal arterial occlusion (PAO) strokes.

METHODS

The Trevo Registry was a prospective open-label MT registry including 2008 patients from 76 sites across 12 countries. Patients were categorized into: PAO: intracranial ICA, and MCA-M1; and DAO: MCA-M2, MCA-M3, ACA, and PCA. Baseline and outcome variables were compared across the PAO vs DAO patients with pre-morbid mRS 0-2.

RESULTS

Among 407 DAOs including 350 (86.0%) M2, 25 (6.1%) M3, 10 (2.5%) ACA, and 22 (5.4%) PCA occlusions, there were 376 DAO with pre-morbid mRS 0-2 which were compared with 1268 PAO patients. The median baseline NIHSS score was lower in DAO (13 [8-18] vs 16 [12-20], P<0.001). There were no differences in terms of age, sex, IV-tPA use, co-morbidities, or time to treatment across DAO vs PAO. The rates of post-procedure reperfusion, symptomatic intracranial hemorrhage (sICH), and 90-mortality were comparable between both groups. DAO showed significantly higher rates of 90-day mRS 0-2 (68.3% vs 56.5%, P<0.001). After adjustment for potential confounders, the level of arterial occlusion was not associated with the chances of excellent outcome (DAO for 90-day mRS 0-1: OR; 1.18, 95% CI [0.90 to 1.54], P=0.225), successful reperfusion or SICH. However, DAO patients were more likely to be functionally independent (mRS 0-2: OR; 1.45, 95% CI [1,09 to 1.92], P=0.01) or dead (OR; 1.54, 95% CI [1.06 to 2.27], P=0.02) at 90 days.

CONCLUSION

Endovascular therapy in DAO appears to result in a comparable safety and technical success profile as in PAO. The potential benefits of DAO thrombectomy should be investigated in future randomized trials.

Approaching the Boundaries of Endovascular Treatment in Acute Ischemic Stroke : Multicenter Experience with Mechanical Thrombectomy in Vertebrobasilar Artery Branch Occlusions

PURPOSE

Little is known about catheter-based endovascular treatment of vertebrobasilar artery branch occlusion (VEBABO) in acute ischemic stroke (AIS). Nonetheless, the experience of mechanical thrombectomy (MT) in distal small sized arteries of the anterior circulation seems promising in AIS. In this multicenter study, we report the feasibility, efficacy and safety of MT in VEBABO.

METHODS

Retrospective analysis of consecutive AIS patients treated with MT due to VEBABO including posterior and anterior inferior cerebellar artery (PICA, AICA) and superior cerebellar artery (SCA) occlusions at seven tertiary care centers between January 2013 and May 2020. Baseline demographics and angiographic outcomes including recanalization success of the affected cerebellar arteries and procedural complications were recorded. Clinical outcomes were evaluated by the modified Rankin scale (mRS) at discharge and 90 days.

RESULTS

Out of 668 endovascularly treated posterior circulation strokes we identified 16 (0.02%) cases with MT for VEBABO. Most frequently, MT of the SCA was done (13/16, 81%). Most VEBABOs occurred after MT of initial basilar/posterior cerebral artery occlusion (9/16, 56%). In 10/16 (63%) procedures, the affected VEBABO was successfully recanalized. Out of four patients three (75%) with isolated VEBABO had benefited from endovascular therapy. Subarachnoid hemorrhage was observed in 3/16 (19%) procedures. The rate of favorable outcome (mRS ≤2) was 40% at discharge and 47% at 90-day follow-up. Mortality was 13% (2/15).

CONCLUSION

The use of MT for VEBABO is rare but appears to be feasible and effective; however, the comparatively high rate of procedure-related hemorrhage highlights that the indications for MT in these occlusion sites should be carefully weighed up.

Effectiveness and Technical Considerations of Solitaire Platinum 4×40 mm Stent Retriever in Mechanical Thrombectomy with Solumbra Technique

OBJECTIVE

The Solitaire Platinum 4×40 mm stent retriever contains radiopaque markers with a long length. We evaluated the effect of Solitaire Platinum 4×40 mm stent retriever in Solumbra technique thrombectomy, and compared it with shorter Solitaire stent retrievers.

METHODS

A total of 70 patients who underwent Solumbra technique thrombectomy with equal diameter (4 mm) and different length (40 vs. 20 mm) Solitaire stent retrievers were divided into two groups : the Solitaire Platinum 4×40 mm stent (4×40) group and the Solitaire FR 4×20 mm stent or Solitaire Platinum 4×20 mm stent (4×20) group. The clinical outcomes, Thrombolysis in Cerebral Infarction score, the first pass reperfusion status, and complications were evaluated and compared between the two groups. Multivariate analysis was performed to evaluate the predictive factors for reperfusion and complete reperfusion from the first pass.

RESULTS

Higher first-pass reperfusion and complete reperfusion were achieved in the 4×40 group (68.0% and 48.0%) than in the 4×20 group (46.7% and 33.3%; p=0.004 and 0.007, respectively). In multivariate analysis, radiopaque device and longer stent retriever were correlated with first-pass reperfusion (p=0.014 and 0.008, respectively) and first-pass complete reperfusion (p=0.022 and 0.012, respectively).

CONCLUSION

Our study demonstrated the usefulness of the Solitaire Platinum 4×40 mm stent retriever, which led to higher firstpass reperfusion and complete reperfusion rates than the Solitaire FR 4×20 mm stent or the Solitaire Platinum 4×20 mm stent, especially in Solumbra technique thrombectomy.

Clinical considerations and assessment of risk factors when choosing endovascular thrombectomy for acute stroke

INTRODUCTION

The advent of endovascular thrombectomy (EVT) has been a game changer for the management of acute ischemic stroke due to large vessel occlusion. However, the selection of suitable candidates for EVT remains a significant challenge.

AREAS COVERED

This review focuses on the clinical, radiological, and procedural considerations for EVT in acute stroke that assist in optimal patient selection.

EXPERT OPINION

All patients presenting with significant clinical deficits with treatable occlusions, who have salvageable brain tissue at presentation might benefit from treatment up to twenty-four hours from symptom onset. Neuroimaging tools form the backbone for this decision making.

Emerging therapies in acute ischemic stroke

Thrombolysis and mechanical thrombectomy have revolutionized the care of patients with acute ischemic stroke. The number of patients who can benefit from these treatments continues to increase as new studies demonstrate that not just time since stroke onset but also collateral circulation influences outcome. Technologies such as telestroke, mobile stroke units, and artificial intelligence are playing an increasing role in identifying and treating stroke. Stroke-systems-of-care models continue to streamline the delivery of definitive revascularization in the age of mechanical thrombectomy.

Repeated mechanical thrombectomy in short-term large vessel occlusion recurrence: multicenter study and systematic review of the literature

BACKGROUND

Data on the frequency and outcome of repeated mechanical thrombectomy (MT) in patients with short-term re-occlusion of intracranial vessels is limited. Addressing this subject, we report our multicenter experience with a systematic review of the literature.

METHODS

A retrospective analysis was conducted of consecutive acute stroke patients treated with MT repeatedly within 30 days at 10 tertiary care centers between January 2007 and January 2020. Baseline demographics, etiology of stroke, angiographic outcome and clinical outcome evaluated by the modified Rankin Scale (mRS) at 90 days were noted. Additionally, a systematic review of reports with repeated MT due to large vessel occlusion (LVO) recurrence was performed.

RESULTS

We identified 30 out of 7844 (0.4%) patients who received two thrombectomy procedures within 30 days due to recurrent LVO. Through systematic review, three publications of 28 participants met the criteria for inclusion. Combined, a total of 58 participants were analyzed: cardioembolic events were the most common etiology for the first (65.5%) and second LVO (60.3%), respectively. Median baseline NIHSS (National Institutes of Health Stroke Scale) was 13 (IQR 8-16) before the first MT and 15 (IQR 11-19) before the second MT (p=0.031). Successful reperfusion was achieved in 91.4% after the first MT and in 86.2% patients after the second MT (p=0.377). The rate of functional independence (mRS 0-2) was 46% at 90 days after the second procedure.

CONCLUSION

Repeated MT in short-term recurrent LVO is a rarity but appears to be safe and effective. The second thrombectomy should be pursued with the same extensive effort as the first procedure as these patients may achieve similar good outcomes.

Impact of complete recanalization on clinical recovery in cardioembolic stroke patients with M2 occlusion

BACKGROUND AND PURPOSE

We investigated the impact of complete recanalization beyond partial recanalization in distal (M2) middle cerebral artery (MCA) occlusion.

METHODS

Data regarding M2 occlusion patients treated with endovascular thrombectomy (EVT) and/or intravenous thrombolysis (tPA) were reviewed from our prospective EVT registry and multicenter tPA (YAMATO study) data bank. Complete recanalization was modified thrombolysis with cerebral infarction score (TICI) of 3 at the end of EVT or similar appearances of both MCAs on magnetic resonance angiography (MRA) within 1.5 h after tPA. Partial recanalization was defined as TICI ≥2b or > 50% recanalization on MRA. At 3 months, favorable outcome was defined as a modified Rankin Scale score ≤ 2.

RESULT

Data on 121 patients were analyzed. EVT-alone was in 38 patients; combined EVT and tPA in 28; and tPA-alone in 55. Complete recanalization was achieved in 27 (22%), partial recanalization in 48 (40%), and no-to-limited recanalization in 46 (38%). At 3 months, 51% of patients had favorable outcomes, and this rate was significantly higher in the complete recanalization group than in the partial and no-to-limited recanalization groups (75% vs. 41% vs. 49%, p = .043). Multivariate regression analysis showed that complete recanalization was an independent parameter related to favorable outcomes (odds ratio 4.78, 95% CI: 1.16-19.73, p = .030). However, combined complete and partial recanalization was not associated with favorable outcomes (odds ratio 1.49, 95% CI 0.53-4.22, p = .449).

CONCLUSION

Complete recanalization, but not partial recanalization, at the end of EVT and tPA therapy is associated with favorable outcomes in patients with M2 occlusion.

Endovascular Treatment of Acute Ischemic Stroke

PURPOSE OF REVIEW

Endovascular thrombectomy (ET), the standard of treatment for emergent large vessel occlusion (ELVO) strokes, has been subject to rigorous efforts to further improve its usage and delivery for optimised patient outcomes. This review aims to provide an outline and discussion about the recently established and emerging recommendations regarding endovascular treatment of stroke.

RECENT FINDINGS

The indications for ET have expanded continually, with perfusion imaging now enabling selection of patients presenting 6-24 h after last-known-well, and improved device and operator proficiency allowing treatment of M2-MCA occlusions and tandem occlusions. Further inclusion of paediatric patients and patients with larger infarct core or milder stroke symptoms for ET has been proposed; however, this remains unproven. This growing applicability is supported by more efficient systems of care, employing modern techniques such as telemedicine, mobile stroke units and helicopter medical services. Ongoing debate exists regarding thrombolytic agent, thrombectomy technique, anaesthesia method and the role of advanced neuroimaging, with upcoming RCTs expected to provide clarification. The journey to further improving the efficacy of ET has advanced and diversified rapidly over recent years, involving improved patient selection, increased utility of advanced neuroimaging and ongoing device redevelopment, within the setting of more efficient, streamlined systems of care. This dynamic and ongoing influx of evidence-based refinements is key to further optimising outcomes for ELVO patients.

Negative-FLAIR vascular hyperintensities serve as a marker of no recanalization during hospitalization in acute stroke

BACKGROUND

Since acute fluid-attenuated inversion recovery vascular hyperintensity (FVH) is indicative of disordered blood flow, FVH is considered a marker of acute major arterial occlusion. Conversely, the role of the absence of FVH (negative-FVH) remains unknown.

METHODS

Consecutive stroke patients were studied via magnetic resonance angiography, within 24 h of onset and major arterial occlusion. All patients were examined using serial angiography to evaluate the presence of recanalization. Patients were classified into negative-FVH and positive-FVH groups.

RESULTS

A total of 72 patients (49 [68%] male patients, aged 76 [66-83] years) were enrolled. Ten patients were allocated to the negative-FVH group and 62 to the positive-FVH group. Initial National Institutes of Health Stroke Scale (NIHSS) score was 4 (2-8) in the negative-FVH group and 10 (4-21) in the positive-FVH group (p = 0.012). Recanalization was achieved in 1 (10%) of the 10 patients in the negative-FVH group and in 49 (79%) of the 62 patients in the positive-FVH group during hospitalization (p < 0.001). Patients with recanalization were older (p = 0.023), had higher NIHSS score (p = 0.008), were admitted earlier (p = 0.014), exhibited a higher prevalence of atrial fibrillation (p = 0.010) and anterior circulation occlusion (p = 0.021), and were more frequently treated with hyperacute recanalization therapy (p = 0.004). Multivariate regression analysis demonstrated that negative-FVH (odds ratio 0.087, 95% confidential interval [0.008-0.988], p = 0.049) was a negative independent factor associated with recanalization during hospitalization.

CONCLUSIONS

In conclusion, negative-FVH in acute stroke was associated with lack of recanalization during hospitalization.

Mechanical Thrombectomy of Distal Occlusions Using a Direct Aspiration First Pass Technique Compared with New Generation of Mini-0.017 Microcatheter Compatible-Stent Retrievers: A Meta-Analysis

BACKGROUND

There are no current evidence-based recommendations on mechanical thrombectomy (MT) in M2 or other distal occlusions. The objective of this paper was to investigate clinical and radiologic outcomes of MT in distal locations using the new generation of mini-0.017 microcatheter compatible-stent retrievers (SRs) compared with a direct aspiration first pass technique (ADAPT) MT.

METHODS

A systematic search was performed for studies published from January 2016 to March 2019. According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we included studies that reported clinical and radiologic outcomes of patients undergoing MT using new generation of SRs or ADAPT in distal locations. The cumulative prevalence was estimated for each outcome. Heterogeneity of the data was assessed by the Higgins index (I²), and a random-effects model was applied.

RESULTS

Fifteen studies and 494 patients were included; 7 studies reported on patients treated with a new SR and 8 studies analyzed patients treated with ADAPT. The rate of thrombolysis in cerebral infarction score 2b-3 after MT for distal occlusions was 80.6% (383 of 494; 95% confidence interval [CI], 74.8%-86.3%; I² = 64.4%). Successful recanalization was comparable after SR use with low-profile devices and ADAPT (176 of 226; 82%; 95% CI, 72.6%-1.5%; I² = 70.5% vs. 207 of 268; 79.4%; 95% CI, 71.8%-86.9%; I² = 60.8%, respectively; P = 0.4). The rate of the modified Rankin scale score of 0-2 at 3 months was higher in the ADAPT group (160 of 251; 68.9%; 95% CI, 51.8%-85.9%; I² = 92.2%) than the SR group (92 of 177; 58.7%; 95% CI, 37.3%-80%; I² = 58.7%; P = 0.01). The mortality rate was lower among the ADAPT group (20 of 251; 5.4%; 95% CI, 1.4%-9%; I² = 63%) than the SR group (16 of 108; 13%; 95% CI, 6%-19%; I² = 13%; P = 0.008).

CONCLUSIONS

MT in distal locations using the new generation of SR yields comparable results compared with ADAPT in terms of recanalization; however, the use of SR is associated with lower functional independence and higher mortality rate.

Blind exchange with mini-pinning technique for distal occlusion thrombectomy

Introduction

Technical improvements to enhance distal occlusion thrombectomy are desirable. We describe the blind catheter exchange technique and report the pinning technique with small devices (‘mini-pinning’) for distal occlusions.

Methods

A retrospective review of a prospective database from January 2015 to August 2018 was performed for cases of distal occlusion in which the ‘blind exchange/mini-pinning’ (BEMP) techniques were used. The technique involves the deployment of a 3 mm Trevo retriever followed by microcatheter removal and blind advancement of a 3MAX aspiration catheter over the bare retriever delivery wire (‘blind exchange’) until clot contact under aspiration. The retriever is subsequently partially recaptured in order to ‘cork’ the thrombus (‘mini-pinning’) and the system pulled as a unit. Patients with distal occlusions treated with BEMP and standard techniques (either 3 mm Trevo or 3MAX) were compared.

Results

Twenty-five vessels were treated in 22 patients. The majority of patients had isolated distal occlusions predominantly in the distal middle cerebral artery (MCA) segments, half of which involved the superior division. The comparison between BEMP (n=25 vessels) and standard techniques (n=144 vessels) revealed balanced groups. One of the highlighted differences was the more distal MCA occlusions among those who underwent BEMP (M3 occlusions 52% vs 22%; p=0.001). Otherwise, the vessel, segments, divisions and luminal diameter were comparable. There was a higher rate of first-pass modified Thrombolysis in Cerebral Infarction 2b–3 (80% vs 56%; p=0.03) and a trend towards higher rates of first-pass full reperfusion (60% vs 40%; p=0.07) with BEMP compared with standard techniques. Final reperfusion and clinical outcomes were comparable.

Conclusion

BEMP appears to be a safe and effective technique for the treatment of distal occlusions. Additional studies are warranted.

Endovascular Thrombectomy for Distal Occlusion Using a Semi-Deployed Stentriever: Report of 2 Cases and Technical Note

Distal intracranial occlusions can sometimes cause significant neurological deficits. Endovascular thrombectomy in these vessels may improve outcome but carry a higher risk of haemorrhagic complications due to the small calibre and tortuosity of the target vessel. We report two cases of isolated M2/3 artery occlusion causing dense hemiplegia that was successfully treated with stent retrieval thrombectomy. A “semi-deployment technique” of a 3 mm stentriever was employed at the M2/3 bifurcation of the middle cerebral artery. Partial stent unsheathing allowed adequate clot engagement while avoiding excessive tension by the stent metal struts along the tortuous course of a distal vessel. Complete revascularization was achieved after first-pass of the stent retriever without complication, resulting in good clinical outcome in both cases. The described semi-deployment technique reduces the radial and tractional force exerted by the stentreiver on small branches, and may reduce the risk of vessel laceration or dissection in distal vessel thrombectomy.

A comparative analysis of 3MAX aspiration versus 3 mm Trevo Retriever for distal occlusion thrombectomy in acute stroke

Background

Although aspiration and stent retriever thrombectomy perform similarly in proximal occlusions, no comparative series are available in distal occlusions. We aimed to compare the 3 mm Trevo Retriever against the 3MAX thromboaspiration catheter in distal arterial occlusions.

Methods

A single-center retrospective review of a prospectively maintained databank for patients treated with the 3 mm Trevo stent retriever or 3MAX thromboaspiration as the upfront approach for distal occlusions (middle cerebral artery mid/distal M2/M3, anterior cerebral artery A1/A2/A3 or posterior cerebral artery P1/P2) from January 2014 to July 2018 was performed. The primary outcome was the rate of distal occlusion first-pass reperfusion (modified Thrombolysis in Cerebral Infarction (mTICI) 2b–3).

Results

Of 1100 patients treated within the study period, 137 patients/144 different arteries were treated with the 3 mm Trevo (n=92) or 3MAX device (n=52). The groups had comparable demographics and baseline characteristics. There was a higher rate of first-pass mTICI 2b–3 reperfusion (62% vs 44%; p=0.03), a trend towards a higher rate of final mTICI 2b–3 reperfusion (84% vs 69%; p=0.05), and lower use of adjuvant therapy (15% vs 31%; p=0.03) with the 3 mm Trevo compared with the 3MAX. The median number of passes (p=0.46), frequency of arterial spasm (p=1.00), rates of parenchymal hematomas (p=0.22)/subarachnoid hemorrhage (p=0.37) in the territory of the approached vessel were similar across the two groups. The 90-day rate of good outcomes (45% vs 46% in the 3 mm Trevo and 3MAX groups, respectively; p=0.84) was comparable. Multivariable regression identified baseline NIH Stroke Scale (NIHSS) score (OR 0.9; 95% CI 0.8 to 0.97; p<0.01) and use of 3 mm Trevo (OR 2.2; 95% CI 1.1 to 4.6; p=0.02) independently associated with first-pass mTICI 2b–3 reperfusion.

Conclusions

In the setting of distal arterial occlusions, the 3 mm Trevo may lead to higher rates of first-pass reperfusion than direct 3MAX thromboaspiration. Lower NIHSS was found to be associated with improved reperfusion rates as observed in more proximal lesions. Further studies are warranted.

Endovascular Metal Devices for the Treatment of Cerebrovascular Diseases

Cerebrovascular disease involves various medical disorders that obstruct brain blood vessels or deteriorate cerebral circulation, resulting in ischemic or hemorrhagic stroke. Nowadays, platinum coils with or without biological modification have become routine embolization devices to reduce the risk of cerebral aneurysm bleeding. Additionally, many intracranial stents, flow diverters, and stent retrievers have been invented with uniquely designed structures. To accelerate the translation of these devices into clinical usage, an in-depth understanding of the mechanical and material performance of these metal-based devices is critical. However, considering the more distal location and tortuous anatomic characteristics of cerebral arteries, present devices still risk failing to arrive at target lesions. Consequently, more flexible endovascular devices and novel designs are under urgent demand to overcome the deficiencies of existing devices. Herein, the pros and cons of the current structural designs are discussed when these devices are applied to the treatment of diseases ranging broadly from hemorrhages to ischemic strokes, in order to encourage further development of such kind of devices and investigation of their use in the clinic. Moreover, novel biodegradable materials and drug elution techniques, and the design, safety, and efficacy of personalized devices for further clinical applications in cerebral vasculature are discussed.

3MAX catheter for thromboaspiration of downstream and new territory emboli after mechanical thrombectomy of large vessel occlusions: initial experience

Distal emboli and emboli to new territories occur in up to 14% and 11% of large vessel occlusion mechanical thrombectomies, respectively. A retrospective review was conducted of 18 consecutive patients with large vessel occlusion acute stroke undergoing mechanical thrombecomy, subsequently developing distal emboli and/or emboli to new territory for which thromboaspiration using the 3MAX catheter was performed. Eighteen distal emboli and two emboli to new territory in 18 patients were treated in the distal M2 and M3 middle cerebral artery, pericallosal and callosomarginal arteries, and P2 posterior cerebral artery (all arteries ≥1.5 mm in diameter). 3MAX thromboaspiration was successful in 13/18 distal emboli and 2/2 emboli to new territory (total 15/20, 75%). 3MAX thromboaspiration resulted in improvement in the final modified treatment in cerebral ischaemia (mTICI) score in 14/18 patients (78%) compared with the initial mTICI score after large vessel occlusion thrombectomy. A shift towards higher final mTICI scores was seen with 3MAX catheter aspiration of distal emboli in this series. The initial mTICI score after large vessel occlusion thrombectomy was 2A in 4/18 (22%) patients and 2B in 14/18 (78%) patients. The final mTICI score after distal emboli/emboli to new territory aspiration improved to 2B in 7/18 (39%) patients, 2C in 3/18 (17%) patients and 3 in 8/18 (44%) patients. No procedural complications were noted. In 13 patients with successful distal emboli/emboli to new territory thromboaspiration, a 90-day modified Rankin score of 0-2 was seen in 10 patients (77%). In five patients with unsuccessful distal emboli/emboli to new territory aspiration, a 90-day modified Rankin score of 0-2 was seen in three patients (60%). 3MAX thromboaspiration of select distal emboli and emboli to new territories is feasible. Larger prospective studies are needed to establish the clinical benefit and safety of this approach.