Frequency and relevance of anterior cerebral artery embolism caused by mechanical thrombectomy of middle cerebral artery occlusion

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.

Efficacy of early integrated rehabilitation therapy on treatment outcomes and limb functional recovery in patients with cerebral embolism: An observational study

Cerebral embolism presents a significant challenge for recovery of motor and neurological function. Early integrated rehabilitation therapy (EIRT) has been proposed as a beneficial approach, yet its efficacy requires thorough evaluation. This retrospective study, conducted from January 2020 to January 2023, involved 117 patient's post-cerebral embolism, divided into an EIRT group (n = 56) receiving EIRT and a control group (n = 61) receiving standard care. The Fugl-Meyer Assessment (FMA) and the National Institutes of Health Stroke Scale (NIHSS) were used to evaluate motor and neurological functions, while muscle strength was categorized from Level 0 (complete paralysis) to Level V (normal strength) to assess physical recovery. Eligibility centered on confirmed cerebral embolism diagnosis, timing of poststroke admission, and baseline functional status. The study adhered to strict ethical standards, with informed consent obtained from all participants. The EIRT group showed substantial improvements in both FMA and NIHSS scores compared to the control group, indicating better motor and neurological recovery. Significant differences were found in the posttreatment FMA (P < .01) and NIHSS scores (P < .01). Muscle strength analysis further confirmed the positive impact of EIRT with more patients in the EIRT group achieving higher levels of muscle strength at discharge. The study demonstrates the potential of EIRT to significantly improve motor and neurological outcomes for patient's post-cerebral embolism. The marked improvements in the observation group suggest that EIRT should be considered for broader application in stroke rehabilitation to enhance recovery and improve quality of life.

Efficacy and safety of combined stent retriever and contact aspiration vs. stent retriever alone on revascularization in patients with acute ischemic stroke: a systematic review and meta-analysis

Objective

Whether the efficacy of combined stent retriever and contact aspiration (S + A) is superior to stent retriever (S) alone for revascularisation in patients with large vessel occlusive stroke remains uncertain. The aim of this meta-analysis was to assess the safety and efficacy of combined stent retriever and contact aspiration for the treatment of acute ischaemic stroke with large vessel occlusion by comparing it with stent retriever alone.

Methods

We systematically searched the PubMed, Embase, Web of Science, and The Cochrane Library databases for randomised controlled trials and observational studies (case-control and cohort studies) published before 1 October 2023 comparing the efficacy of combined stent retriever and contact aspiration versus tent retriever alone in patients with large vessel occlusive stroke. The end point of the primary efficacy observed in this meta-analysis study was the rate of first pass nearly complete or complete recanalisation (mTICI 2c-3). Secondary effectiveness nodes were: rate of first pass successful recanalisation (mTICI 2b-3), rate of near-complete or complete recanalisation of the postoperative vessel, rate of successful recanalisation of the postoperative vessel, and MRS 0-2 within 90 days. Safety endpoints were interoperative embolism, symptomatic intracranial haemorrhage, and mortality within 90 days.

Results

A total of 16 studies were included in the literature for this meta-analysis, with a total of 7,320 patients (S + C group: 3,406, S group: 3,914). A comprehensive analysis of the included literature showed that combined stent retriever and contact aspiration had a higher rate of near-complete or complete recanalisation of the postoperative vessel [OR = 1.53, 95% CI (1.24, 1.88), p < 0.0001] and rate of successful recanalisation of the postoperative vessel compared to stent retriever alone [OR = 1.83, 95% CI (1.55, 2.17), p < 0.00001]; there were no statistically significant differences between the two groups in terms of the rate of first pass nearly complete or complete recanalisation [OR = 1.00, 95% CI (0.83, 1.19), p = 0.96], rate of first pass successful recanalisation [OR = 1.02, 95% CI (0.85, 1.24), p = 0.81], interoperative embolism [OR = 0.93, 95% CI (0.72, 1.20), p = 0.56], symptomatic intracranial haemorrhage [OR = 1.14, 95% CI (0.87, 1.48), p = 0.33], MRS 0-2 within 90 days [OR = 0.89, 95% CI (0.76, 1.04), p = 0.14] and mortality within 90 days [OR = 1.11, 95% CI (0.94, 1.31), p = 0.22].

Conclusion

Combined stent retriever and contact aspiration has a higher rate of postprocedural revascularisation (mTICI 2c-3/mTICI 2b-3) compared with stent retriever alone in patients with large vessel occlusion stroke. In addition, it was not superior to stenting alone in terms of the rate of first pass recanalisation (mTICI 2c-3/mTICI 2b-3), interoperative embolisation, symptomatic intracranial haemorrhage, good functional prognosis within 90 days and mortality within 90 days.

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.

Comparison between transradial and transfemoral mechanical thrombectomy for ICA and M1 occlusions: insights from the Stroke Thrombectomy and Aneurysm Registry (STAR)

BACKGROUND

The role for the transradial approach for mechanical thrombectomy is controversial. We sought to compare transradial and transfemoral mechanical thrombectomy in a large multicenter database of acute ischemic stroke.

METHODS

The prospectively maintained Stroke Thrombectomy and Aneurysm Registry (STAR) was reviewed for patients who underwent mechanical thrombectomy for an internal carotid artery (ICA) or middle cerebral artery M1 occlusion. Multivariate regression analyses were performed to assess outcomes including reperfusion time, symptomatic intracerebral hemorrhage (ICH), distal embolization, and functional outcomes.

RESULTS

A total of 2258 cases, 1976 via the transfemoral approach and 282 via the transradial approach, were included. Radial access was associated with shorter reperfusion time (34.1 min vs 43.6 min, P=0.001) with similar rates of Thrombolysis in Cerebral Infarction (TICI) 2B or greater reperfusion (87.9% vs 88.1%, P=0.246). Patients treated via a transradial approach were more likely to achieve at least TICI 2C (59.6% vs 54.7%, P=0.001) and TICI 3 reperfusion (50.0% vs 46.2%, P=0.001), and had shorter lengths of stay (mean 9.2 days vs 10.2, P<0.001). Patients treated transradially had a lower rate of symptomatic ICH (8.0% vs 9.4%, P=0.047) but a higher rate of distal embolization (23.0% vs 7.1%, P<0.001). There were no significant differences in functional outcome at 90 days between the two groups.

CONCLUSIONS

Radial and femoral thrombectomy resulted in similar clinical outcomes. In multivariate analysis, the radial approach had improved revascularization rates, fewer cases of symptomatic ICH, and faster reperfusion times, but higher rates of distal emboli. Further studies on the optimal approach are necessary based on patient and disease characteristics.

Impact of stent-retriever tip design on distal embolization during mechanical thrombectomy: a randomized in vitro evaluation

BACKGROUND

Repeated number of passes, clot fragmentation, and distal embolization during mechanical thrombectomy (MT) lead to worse clinical outcomes in acute ischemic stroke. This study aimed to assess the recanalization and embolic outcomes of different stent-retrievers (SRs): open-tip SR (Solitaire X 6×40 mm), closed-tip SR (EmboTrap II 5×33 mm), and filter-tip SR (NeVa NET 5.5×37 mm).

METHODS

Stiff-friable clot analogs were used to create middle cerebral artery (M1-MCA) occlusions in a benchtop model. After occlusion, experiments were randomized into one of the three treatment arms. The thrombectomy technique consisted of retrieving the SR into a balloon guide catheter under proximal flow arrest and continuous aspiration. A total of 150 single-attempt cases were performed (50 cases/treatment arm). Distal emboli (>100 µm) were collected and analyzed after each experiment.

RESULTS

Filter-tip SR achieved a non-significantly higher first-pass recanalization rate than open-tip SR and closed-tip SR (66% vs 48% vs 44%; P=0.064). Filter-tip SR prevented clot fragments>1 mm from embolizing distal territories in 44% of cases, compared with 16% in open-tip SR and 20% in closed-tip (P=0.003). There were no significant differences between treatment arms in terms of total emboli count (open-tip=19.2±13.1, closed-tip=19.1±10.7, filter-tip=17.2±13.0; P=0.660). Nonetheless, the number of large emboli (>1 mm) and total area of emboli were significantly lower in the filter-tip arm (n=0.88±1.2, A=2.06±1.85 mm2) than in the closed-tip arm (n=2.34±3.38, A=4.06±4.80 mm2; P<0.05).

CONCLUSIONS

When facing fragment-prone clots, the filter-tip SR significantly reduces the number of large clots (>1 mm) that embolize distally during an MT procedure, which in turn may increase the chances of first-pass complete recanalization.

A prospective, multicentre, registry study of RECO in the endovascular treatment of acute ischaemic stroke

The RECO is a novel endovascular treatment (EVT) device that adjusts the distance between two mesh segments to axially hold the thrombus. We organized this postmarket study to assess the safety and performance of RECO in acute ischaemic stroke (AIS) patients with large vessel occlusion (LVO). This was a single-arm prospective multicentre study that enrolled patients as first-line patients treated with RECO at 9 stroke centres. The primary outcome measures included functional independence at 90 days (mRS 0-2), symptomatic intracranial haemorrhage (sICH), time from puncture to recanalization and time from symptom onset to recanalization. The secondary outcome measures were a modified thrombolysis in cerebral infarction (mTICI) score of 2b or 3 after the first attempt and at the end of the procedure and the all-cause mortality rate within 90 days. From May 22, 2020, to July 30, 2022, a total of 268 consecutive patients were enrolled in the registry. The median puncture-to-recanalization time was 64 (IQR, 45-92), and the symptom onset-to-recanalization time was 328 min (IQR, 228-469). RECO achieved successful reperfusion (mTICI 2b-3) after the first pass in 133 of 268 patients (49.6%). At the end of the operation, 96.6% of the patients reached mTICI 2b-3, and 97.4% of the patients ultimately achieved successful reperfusion. Sixteen (7.2%) patients had sICH. A total of 132 (49.3%) patients achieved functional independence at 90 days, and the all-cause mortality rate within 90 days was 17.5%. In this clinical experience, the RECO device achieved a high rate of complete recanalization with a good safety profile and favourable 90-day clinical outcomes.Clinical trial registration: URL: https://www.clinicaltrials.gov/ ; Unique identifier: NCT04840719.

Predictors of Emboli in Mechanical Thrombectomy for Anterior Circulation Stroke

OBJECTIVE

Emboli commonly occurs in mechanical thrombectomy (MT). The objective of this study was to analyze predicting factors of emboli after MT.

METHODS

Patients who underwent MT with successful reperfusion for anterior circulation occlusion were enrolled. Emboli included distal emboli at digital subtraction angiography (DSA) and unexpected embolic infarct on diffusion-weighted image (DWI) without distal emboli at DSA. Baseline characteristics, procedural details, angiographic outcomes, and clinical outcomes were reviewed. Multivariable analyses were performed to evaluate predictive factors for the occurrence of emboli.

RESULTS

Of 601 patients, 149 (24.8%) patients had distal emboli at DSA, and 169 (28.1%) patients had unexpected embolic infarction on DWI even without distal emboli at DSA. A total of 318 (52.9%) patients were enrolled in the embolic group, and 283 (47.1%) patients were assigned to the non-embolic group. In multivariate analysis, larger microcatheter (OR 1.26, 95% CI 1.12-1.94; p = 0.047), clot passage (OR 1.33, 95% CI 1.07-1.87; p = 0.041), use of balloon guide catheter (BGC) (OR 0.70, 95% CI 0.52-0.92; p = 0.014), early ballooning of BGC (OR 0.68, 95% CI 0.50-0.90; p = 0.009), and longer stent retriever (OR 0.72, 95% CI 0.54-0.90; p = 0.029) were associated with occurrence of emboli.

CONCLUSION

MT with only a stent retriever, use of a larger microcatheter, and clot passage might increase the risk of emboli. In contrast, contact aspiration thrombectomy, use of BGC, early ballooning of BGC, and use of longer stent retrievers could reduce the chance of emboli.

Mechanical thrombectomy for the treatment of primary and secondary anterior cerebral artery occlusions: insights from STAR

BACKGROUND

The safety and efficacy of mechanical thrombectomy (MT) for the treatment of acute anterior cerebral artery (ACA) occlusions have not clearly been delineated. Outcomes may be impacted based on whether the occlusion is isolated to the ACA (primary ACA occlusion) or occurs in conjunction with other cerebral arteries (secondary).

METHODS

We performed a retrospective review of the multicenter Stroke Thrombectomy and Aneurysm (STAR) database. All patients with MT-treated primary or secondary ACA occlusions were included. Baseline characteristics, procedural outcomes, complications, and clinical outcomes were collected. Primary and secondary ACA occlusions were compared using the Mann-Whitney U test and Kruskal-Willis test for continuous variables and the χ2 test for categorical variables.

RESULTS

The study cohort comprised 238 patients with ACA occlusions (49.2% female, median (SD) age 65.6 (16.7) years). The overall rate of successful recanalization was 75%, 90-day good functional outcome was 23%, and 90-day mortality was 35%. There were 44 patients with a primary ACA occlusion and 194 patients with a secondary ACA occlusion. When adjusted for baseline variables, the rates of successful recanalization (68% vs 76%, P=0.27), 90-day good functional outcome (41% vs 19%, P=0.38), and mortality at 90 days (25% vs 38%, P=0.12) did not differ between primary and secondary ACA occlusion groups.

CONCLUSION

Clinical and procedural outcomes are similar between MT-treated primary and secondary ACA occlusions for select patients. Our findings demonstrate the need for established criteria to determine ideal patient and ACA stroke characteristics amenable to MT treatment.

Mechanical Thrombectomy for Patients with Occlusions in Both the Anterior Cerebral Artery and Middle Cerebral Artery: Case Series and Review of the Literature

Objective

Most large-vessel occlusions (LVOs) amenable to acute recanalization occur in the internal carotid or middle cerebral artery. However, few LVOs with a multivessel disease can be difficult to treat. This study aimed to determine the outcomes of mechanical thrombectomy in patients with both anterior and middle cerebral artery occlusions.

Methods

We retrospectively collected data for patients who had undergone mechanical thrombectomy since January 2016 at Fukushima Medical University and its affiliated institutions (10 institutions). Patients with occluded vessels in the anterior and middle cerebral arteries were selected, and patient background, treatment course, and outcomes were reviewed.

Results

A total of 341 mechanical thrombectomies were performed during the study period. Seven patients had occlusions involving both anterior and middle cerebral arteries. In these seven patients, the median time from onset to imaging, imaging to puncture, and puncture to recanalization was 106, 60, and 74 min, respectively. Only one patient (14%) had a modified Rankin Scale of 0-2 at 90 days.

Conclusion

Comorbid anterior cerebral artery occlusion may worsen the outcome of patients with middle cerebral artery occlusion.

Comparison of a direct aspiration first pass technique vs. stent retriever thrombectomy for the treatment of acute large vessel occlusion stroke in the anterior circulation with atrial fibrillation

Objectives

The stent retriever thrombectomy (SRT) and a direct aspiration first-pass technique (ADAPT) are the two main mechanical thrombectomy (MT) techniques for acute ischemic stroke. Few data are available for comparing the therapeutic effects associated with the two mechanical thrombectomy techniques in acute ischemic stroke with atrial fibrillation. The purpose of this study was to compare the efficacy and safety of both techniques for the treatment of acute large vessel occlusion stroke in the anterior circulation with atrial fibrillation.

Methods

Retrospective analysis was performed in stroke patients with atrial fibrillation admitted to Guangzhou Red Cross Hospital from January 2018 to June 2022 who received mechanical thrombectomy by either SRT or ADAPT. Comparisons were made with regards to the initial traits, course of therapy, effectiveness indicators, and complications of these individuals. The primary outcome is recanalization rate.

Results

In this study, after screening 431 patients, 92 eligible patients, with 48 patients received SRT and 44 patients received ADAPT, were included. There was no significant difference in the recanalization rate between the two groups (SRT 87.5% vs. ADAPT 84.1%, P = 0.639). Compared with SRT, patients in ADAPT group had a shorter puncture to recanalization time [33.5 min (27.0-59.5) vs. 50.5 min (31.5-91.5), P = 0.009], a higher first pass success recanalization rate (54.5 vs. 33.3%, p = 0.040), and a higher rate of patients with improvement of NIHSS scores ≥4 at discharge (84.1 vs. 56.3%, P = 0.004). However, distal embolization occurred more frequently in the ADAPT group than that in SRT group (50.0 vs. 22.9%, P = 0.007). There was no significant difference between the two groups in the 3-month mRS score, symptomatic cerebral hemorrhage, or mortality.

Conclusions

Compared with SRT, ADAPT has similar recanalization rate for the treatment of acute large vessel occlusion stroke in the anterior circulation with atrial fibrillation. However, ADAPT might be more effective in terms of shorter puncture to recanalization time and higher first pass success recanalization rate. Further studies are needed for confirming our results.

Mechanical Thrombectomy for the Treatment of Anterior Cerebral Artery Occlusion: A Systematic Review of the Literature

BACKGROUND

The overall safety and efficacy of mechanical thrombectomy for anterior cerebral artery strokes remain unclear.

PURPOSE

Our aim was to summarize procedural and clinical outcomes in patients who underwent mechanical thrombectomy for treatment of anterior cerebral artery ischemic stroke.

DATA SOURCES

A systematic literature review was performed using PubMed, Ovid MEDLINE, and the Web of Science from inception until March 4, 2022.

STUDY SELECTION

We identified 9 studies with a total of 168 patients with mechanical thrombectomy-treated anterior cerebral artery occlusions.

DATA ANALYSIS

Recanalization, procedural data, and clinical outcome at last follow-up were collected and summarized. Categoric variables were reported as proportions. The χ² test of independence or the Kruskal-Wallis test was performed to assess the relationship between selected variables and the anterior cerebral artery embolus type (ie, primary isolated anterior cerebral artery, primary combined anterior cerebral artery, and secondary anterior cerebral artery occlusion) or the mechanical thrombectomy technique.

DATA SYNTHESIS

For mechanical thrombectomy-treated anterior cerebral artery occlusions, recanalization modified TICI 2b/3 was achieved in 80%, postprocedural complications occurred in 17% of patients, and the 90-day mortality rate was 19%. The rate of symptomatic intracranial hemorrhage varied depending on the anterior cerebral artery embolus type (χ² = 8.45, P = .01).

LIMITATIONS

This analysis did not consider factors such as small-study effects that affect reliability and limit interpretation.

CONCLUSIONS

Mechanical thrombectomy for the treatment of anterior cerebral artery occlusions is safe and efficacious, offering a favorable rate of recanalization and procedural complications. Mechanical thrombectomy-treated anterior cerebral artery occlusions appear to have lower rates of short-term good functional outcomes and an increased risk of symptomatic intracerebral hemorrhage compared with mechanical thrombectomy-treated MCA/ICA occlusions. Single and multicenter studies are needed to further examine the safety and efficacy of mechanical thrombectomy-treated anterior cerebral artery occlusions.

Safety and Efficacy of the Novel Low-Profile APERIO Hybrid17 for a Treatment of Proximal and Distal Vessel Occlusion in Acute Ischemic Stroke: A Multi-Center Experience

OBJECTIVE

To report our initial experience with the novel low-profile APERIO Hybrid17 Thrombectomy Device (AP17) for proximal and distal vessel occlusions in acute ischemic stroke.

METHODS

A multicentric retrospective analysis of patients treated with the AP17 was performed. The primary effectiveness endpoint was first-pass TICI ≥2b (Thrombolysis in cerebral infarction scale). The primary safety endpoint was the occurrence of hemorrhagic complications. Further outcome measures were number of passes, device-related complications, and 3-month functional outcome.

RESULTS

The AP17 was used in 71 patients (mean age: 73 years) with a median baseline National Institutes of Health Stroke Scale score of 9. Treated vessels were the carotid-T in 8 cases (11%), the M1-segment in 16 (23%), the M2-segment in 29 (41%), the anterior cerebral artery in 3 (4%), and basilar/posterior cerebral arteries in 15 (21%). The rates of first-pass and final TICI ≥2b were 75.6% and 92.7%, retrospectively, with a mean number of passes of 3 ± 2. Final TICI ≥2b rates were comparable between large and medium vessel occlusions. Symptomatic intracranial hemorrhages were recorded in 2 cases (2.8%). At 3-month clinical follow-up, a modified Rankin scale score ≤2 was achieved in 69.0% (29/42). The all-cause mortality at discharge was 17.4%.

CONCLUSIONS

The AP17 was associated with a reasonable safety and efficacy profile for both proximal and distal vessel occlusions. These results may contribute to establish mechanical thrombectomy for distal occlusions.

Retrograde Angiography to Detect Dropped Thrombus in Mechanical Thrombectomy

OBJECTIVE

The risk of embolization to distal territory or to new territory in mechanical thrombectomy remains a major issue despite advancements in technological device. This condition can be caused by a large and firm dropped thrombus without passing through a guiding catheter during stent retriever or aspiration catheter withdrawal. This report introduced a novel technique referred to as retrograde angiography to detect dropped thrombus.

METHODS

The retrograde angiography to detect dropped thrombus technique is a kind of retrograde angiography that consists of a contrast medium injection via a distal microcatheter and aspiration through an inflated balloon-guiding catheter. This method was used to detect dropped thrombus at the balloon-guiding catheter tip when back flow was blocked from the balloon-guiding catheter after stent retriever or aspiration catheter withdrawal. We retrospectively reviewed four consecutive patients who underwent the retrograde angiography to detect dropped thrombus technique during mechanical thrombectomy for acute ischemic stroke due to large vessel occlusion in the anterior circulation between January 2018 and January 2021.

RESULTS

Three of four patients had dropped thrombus, which was diagnosed with the technique and retrieved completely with subsequent procedures while maintaining the balloon-guiding catheter inflated. None of the patients experienced embolization to distal territory/embolization to new territory, and a successful reperfusion was achieved in all four cases.

CONCLUSIONS

The retrograde angiography to detect dropped thrombus is a technique to detect a dropped thrombus at the balloon-guiding catheter tip and allows us to retrieve it with subsequent mechanical thrombectomy procedures while maintaining the balloon-guiding catheter inflated and it may be useful for reducing the risk of embolization to distal territory/embolization to new territory.

A Meta-analysis of Combined Aspiration Catheter and Stent Retriever versus Stent Retriever Alone for Large-Vessel Occlusion Ischemic Stroke

BACKGROUND

The efficacy of combined aspiration catheter and stent retriever compared with stent retriever alone for the treatment of large-vessel occlusion acute ischemic stroke is unclear.

PURPOSE

Our aim was to conduct a systematic literature review and meta-analysis on several metrics of efficacy comparing aspiration catheter and stent retriever with stent retriever alone.

DATA SOURCES

MEDLINE and the Cochrane Library Databases were searched. Randomized controlled trials and case-control and cohort studies were included.

STUDY SELECTION

Ten comparative studies were included detailing a combined 1495 patients with aspiration catheter and stent retriever and 1864 with stent retrievers alone.

DATA ANALYSIS

Data on first pass effect (TICI 2b/2c/3 after first pass), final successful reperfusion (modified TICI ≥2b), and 90-day functional independence (mRS ≤ 2) were collected. Meta-analysis was performed using a random-effects model.

DATA SYNTHESIS

There was a pooled composite first pass effect of 40.8% (611/1495) versus 32.6% (608/1864) for aspiration catheter and stent retriever and stent retriever alone, respectively (P < .0001). Similarly, on a meta-analysis, aspiration catheter and stent retriever were associated with a higher first pass effect compared with stent retriever alone (OR = 1.63; 95% CI, 1.20-2.21; P = .002; I² = 72%). There was no significant difference in composite rates of successful reperfusion between aspiration catheter and stent retriever (72.8%, 867/1190) and stent retriever alone (70.8%, 931/1314) (P = .27) or on meta-analysis (OR = 1.31; CI, 0.81-2.12; P = .27; I² = 82%). No difference was found between aspiration catheter and stent retriever and stent retriever alone on 90-day functional independence (OR = 1.02; 95% CI, 0.77-1.36; P = .88; I² = 40%).

LIMITATIONS

This study is limited by high interstudy heterogeneity.

CONCLUSIONS

On meta-analysis, aspiration catheter and stent retriever are associated with a superior first pass effect compared with stent retriever alone, but they are not associated with statistically different final reperfusion or functional independence.

Leptomeningeal anastomoses: Mechanisms of pial collateral remodeling in ischemic stroke

Arterial collateralization, as determined by leptomeningeal anastomoses or pial collateral vessels, is a well‐established vital player in cerebral blood flow restoration and neurological recovery from ischemic stroke. A secondary network of cerebral collateral circulation apart from the Circle of Willis, exist as remnants of arteriole development that connect the distal arteries in the pia mater. Recent interest lies in understanding the cellular and molecular adaptations that control the growth and remodeling, or arteriogenesis, of these pre‐existing collateral vessels. New findings from both animal models and human studies of ischemic stroke suggest a multi‐factorial and complex, temporospatial interplay of endothelium, immune and vessel‐associated cell interactions may work in concert to facilitate or thwart arteriogenesis. These valuable reports may provide critical insight into potential predictors of the pial collateral response in patients with large vessel occlusion and may aid in therapeutics to enhance collateral function and improve recovery from stroke.

This article is categorized under:

Neurological Diseases > Molecular and Cellular Physiology

A human brain test bed for research in large vessel occlusion stroke

OBJECTIVE

Endovascular removal of emboli causing large vessel occlusion (LVO)-related stroke utilizing suction catheter and/or stent retriever technologies or thrombectomy is a new standard of care. Despite high recanalization rates, 40% of stroke patients still experience poor neurological outcomes as many cases cannot be fully reopened after the first attempt. The development of new endovascular technologies and techniques for mechanical thrombectomy requires more sophisticated testing platforms that overcome the limitations of phantom-based simulators. The authors investigated the use of a hybrid platform for LVO stroke constructed with cadaveric human brains.

METHODS

A test bed for embolic occlusion of cerebrovascular arteries and mechanical thrombectomy was developed with cadaveric human brains, a customized hydraulic system to generate physiological flow rate and pressure, and three types of embolus analogs (elastic, stiff, and fragment-prone) engineered to match mechanically and phenotypically the emboli causing LVO strokes. LVO cases were replicated in the anterior and posterior circulation, and thrombectomy was attempted using suction catheters and/or stent retrievers.

RESULTS

The test bed allowed radiation-free visualization of thrombectomy for LVO stroke in real cerebrovascular anatomy and flow conditions by transmural visualization of the intraluminal elements and procedures. The authors were able to successfully replicate 105 LVO cases with 184 passes in 12 brains (51 LVO cases and 82 passes in the anterior circulation, and 54 LVO cases and 102 passes in the posterior circulation). Observed recanalization rates in this model were graded using a Recanalization in LVO (RELVO) scale analogous to other measures of recanalization outcomes in clinical use.

CONCLUSIONS

The human brain platform introduced and validated here enables the analysis of artery-embolus-device interaction under physiological hemodynamic conditions within the unmodified complexity of the cerebral vasculature inside the human brain.

Experimental Evaluation of the Risk of Distal Embolization during Endovascular Clot Retrieval Using Various Techniques

Background:

This study was conducted to evaluate various devices and techniques for endovascular thrombectomy that can reduce the risk of intraprocedural distal embolism in a preliminary in vitro setting with different types of thrombi.

Materials and Methods:

Endovascular clot retrieval was performed in a vascular model with collateral circulation. White and red thrombi were prepared using whole blood collected from a pig. A Direct Aspiration First Pass Technique (ADAPT), simple stentretrieving with and without proximal flow arrest by a guiding balloon (SR [B+] and SR [B±]), the AspirationRetriever Technique for Stroke (ARTS), and A stentretrieving into an Aspiration catheter with Proximal balloon (ASAP) were performed three times, respectively. The saline samples that were collected at the distal side during each procedure were examined using a particle counter. The particles were counted and categorized into three groups based on size (100 μm).

Results:

SR (B−) and SR (B+) could not achieve complete retrieval of the clot, especially using the white thrombus. ASAP was the only method that was able to retrieve the clots in all attempts. In both clot types, SR (B−), SR (B+), and ARTS, which involved a temporary flow restoration through stent deployment, demonstrated the migration of a greater number of particles measuring >100 μm in size than that shown by ADAPT and ASAP.

Conclusions:

ASAP was the safest method in terms of intraprocedural clot migration among the five methods evaluated in this study. Temporary flow restoration through stent deployment may affect the dangerous distal clot migration.

First-Pass Reperfusion by Mechanical Thrombectomy in Acute M1 Occlusion: The Size of Retriever Matters

Introduction: Single-pass complete reperfusion using stent retrievers has been shown to improve functional outcome in patients with large vessel occlusion strokes. The aim of this study was to investigate the optimal size of stent retrievers to achieve one-pass complete reperfusion by mechanical thrombectomy. Methods: The study evaluated the results of aspiration-assisted mechanical thrombectomy of acute isolated occlusion of the middle cerebral artery in the M1 segment with a novel 5 × 40-mm stent retriever compared to the usual 4 × 20-mm device. Reperfusion status was quantified using the Thrombolysis In Cerebral Infarction (TICI) scale. We hypothesized that thrombectomy of M1 occlusions with 5 × 40-mm stent retriever yields higher rates of complete first-pass reperfusion (FP) (TICI ≥2c after one pass) and successful or modified FP (mFP) (TICI ≥2b after one pass) than thrombectomy with 4 × 20. We included isolated M1 occlusions treated with pRESET 5 × 40 (phenox) as first-choice device for thrombectomy and compared with M1 occlusions treated with pRESET 4 × 20. We excluded patients with additional occlusions or tandem stenosis or who received an intracranial stent or angioplasty as a part of the endovascular treatment. Results: One hundred thirteen patients were included in the 4 × 20 group and 57 patients in the 5 × 40 group. The 5 × 40 group achieved higher FP compared to 4 × 20 group [61.4% (35 of 57 patients) vs. 40.7% (46 of 113), respectively; adjusted odds ratio (OR) and 95% confidence interval (95% CI) = 2.20 (1.08-4.48), p = 0.030] and a higher mFP [68.4%, 39 of 57 patients vs. 48.7%, 55 of 113; adjusted OR (95% CI) = 2.11 (1.04-4.28), p = 0.037]. Frequency of successful reperfusion (TICI ≥2b) was similar in both groups (100 vs. 97.3%), but frequency of complete reperfusion (TICI ≥2c) was higher in the 5 × 40 group [82.5 vs. 61.9%, adjusted OR (95% CI) = 2.47 (1.01-6.04), p = 0.047]. Number of passes to achieve reperfusion was lower in the 5 × 40 group than in the 4 × 20 group [1.6 ± 1.1 vs. 2 ± 1.4, p = 0.033; adjusted incidence rate ratio (95% CI) = 0.84 (0.69-1.03), p = 0.096]. Modified Rankin scale at 90 days was similar in 5 × 40 and 4 × 20 groups. Conclusions: The size of stent retriever matters in acute M1 occlusions treated with aspiration-assisted mechanical thrombectomy. A longer stent retriever with a larger nominal diameter achieves a higher complete and successful FP and higher successful reperfusion compared to a shorter stent retriever.

Anterior Cerebral Artery Stroke: Role of Collateral Systems on Infarct Topography

[Figure: see text].

Clinical prognosis of isolated anterior cerebral artery territory infarction: a retrospective study

Background

Isolated anterior cerebral artery territory (ACA) infarction is a rare phenomenon, and is known to have distinctive clinical features. Little is known regarding the clinical prognosis of isolated ACA territory infarction with associated factors, and its impact on dwelling and job status. We investigated the short- and long-term outcomes of anterior cerebral artery (ACA) territory infarction, and the associated factors involved in the development of the distinctive symptoms.

Methods

This retrospective study in a prospective cohort of acute ischaemic stroke patients included consecutively enrolled patients with isolated ACA territory infarction. We investigated the functional status using the modified Rankin scale (mRS) score at discharge, three months’ post-discharge, and one-year post-discharge. We also investigated the occlusion site of the ACA (proximal vs. distal); presence of distinctive symptoms of ACA territory infarction including behaviour changes, indifference, aphasia, and urinary incontinence; and the effect of these symptoms on dwelling and job status one year after discharge.

Results

Between April 2014 and March 2019, 47 patients with isolated ACA territory infarction were included. Twenty-nine patients (61.7 %) had good outcomes (mRS ≤ 2) at discharge; however, the mRS score increased at three months (40; 85.1 %, p < 0.001) and one year (41; 87.2 %) post-discharge. Occlusion of the ACA proximal segment was independently associated with the development of distinctive symptoms (adjusted odds ratio, 17.68; 95 % confidence interval: 2.55–122.56, p < 0.05). Twenty-one (48.8 %) patients with good outcomes at one year experienced a change in dwelling status and job loss; 20 (95.2 %) of them had distinctive ACA territory symptoms with proximal ACA occlusion.

Conclusions

Short- and long-term outcomes of isolated ACA territory infarction were favourable. However, proximal segment occlusion was associated with the development of distinctive symptoms, possibly related to future dwelling and job status.

Novel Human Acute Ischemic Stroke Blood Clot Analogs for In Vitro Thrombectomy Testing

BACKGROUND AND PURPOSE

Previous studies have successfully created blood clot analogs for in vitro endovascular device testing using animal blood of various species. Blood components vary greatly among species; therefore, creating clot analogs from human blood is likely a more accurate representation of thrombi formed in the human vasculature.

MATERIALS AND METHODS

Following approval from the Mayo Clinic institutional review board, human whole-blood and platelet donations were obtained from the blood transfusion service. Twelve clot analogs were created by combining different ratios of red blood cells + buffy coat, plasma, and platelets. Thrombin and calcium chloride were added to stimulate coagulation. Clot composition was assessed using histologic and immunohistochemical staining. To assess the similarities of mechanical properties to patient clots, 3 types of clot analogs (soft, elastic, and stiff) were selected for in vitro thrombectomy testing.

RESULTS

The range of histopathologic compositions produced is representative of clots removed during thrombectomy procedures. The red blood cell composition ranged from 8.9% to 91.4%, and fibrin composition ranged from 3.1% to 53.4%. Platelets (CD42b) and von Willebrand Factor ranged from 0.5% to 47.1% and 1.0% to 63.4%, respectively. The soft clots had the highest first-pass effect and successful revascularization rates followed by the elastic and stiff clots. Distal embolization events were observed when clot ingestion could not be achieved, requiring device pullback. The incidence rate of distal embolization was the highest for the stiff clots due to the weak clot/device integration.

CONCLUSIONS

Red blood cell-rich, fibrin-rich, and platelet-rich clot analogs that mimic clots retrieved from patients with acute ischemic stroke were created in vitro. Differing retrieval outcomes were confirmed using in vitro thrombectomy testing in a subset of clots.

Modelling the impact of clot fragmentation on the microcirculation after thrombectomy

Many ischaemic stroke patients who have a mechanical removal of their clot (thrombectomy) do not get reperfusion of tissue despite the thrombus being removed. One hypothesis for this 'no-reperfusion' phenomenon is micro-emboli fragmenting off the large clot during thrombectomy and occluding smaller blood vessels downstream of the clot location. This is impossible to observe in-vivo and so we here develop an in-silico model based on in-vitro experiments to model the effect of micro-emboli on brain tissue. Through in-vitro experiments we obtain, under a variety of clot consistencies and thrombectomy techniques, micro-emboli distributions post-thrombectomy. Blood flow through the microcirculation is modelled for statistically accurate voxels of brain microvasculature including penetrating arterioles and capillary beds. A novel micro-emboli algorithm, informed by the experimental data, is used to simulate the impact of micro-emboli successively entering the penetrating arterioles and the capillary bed. Scaled-up blood flow parameters-permeability and coupling coefficients-are calculated under various conditions. We find that capillary beds are more susceptible to occlusions than the penetrating arterioles with a 4x greater drop in permeability per volume of vessel occluded. Individual microvascular geometries determine robustness to micro-emboli. Hard clot fragmentation leads to larger micro-emboli and larger drops in blood flow for a given number of micro-emboli. Thrombectomy technique has a large impact on clot fragmentation and hence occlusions in the microvasculature. As such, in-silico modelling of mechanical thrombectomy predicts that clot specific factors, interventional technique, and microvascular geometry strongly influence reperfusion of the brain. Micro-emboli are likely contributory to the phenomenon of no-reperfusion following successful removal of a major clot.

A review of endovascular treatment for medium vessel occlusion stroke

Medium-vessel occlusions (MeVOs), that is, occlusions of the M2/3 middle cerebral artery, A2/3 anterior cerebral artery, and P2/3 posterior cerebral artery segments, account for 25%-40% of all acute ischemic stroke cases. Clinical outcomes of MeVO stroke with intravenous thrombolysis, which is the current standard of care, are moderate at best. With improving imaging technologies and a growing literature, MeVOs are increasingly recognized as a target for endovascular treatment (EVT). For the time being, there is limited but promising evidence for the safety and efficacy of MeVO EVT, and many neurointerventionists are already routinely offering EVT for MeVO stroke, despite the lack of clear guideline recommendations. In this article, we review the evidence on endovascular treatment for MeVO stroke and summarize the available literature on current imaging strategies, commonly used EVT selection criteria, EVT techniques, and outcome assessment for MeVO stroke.

Time-to-Maximum of the Tissue Residue Function Improves Diagnostic Performance for Detecting Distal Vessel Occlusions on CT Angiography

BACKGROUND AND PURPOSE

Detecting intracranial distal arterial occlusions on CTA is challenging but increasingly relevant to clinical decision-making. Our purpose was to determine whether the use of CTP-derived time-to-maximum of the tissue residue function maps improves diagnostic performance for detecting these occlusions.

MATERIALS AND METHODS

Seventy consecutive patients with a distal arterial occlusion and 70 randomly selected controls who underwent multimodal CT with CTA and CTP for a suspected acute ischemic stroke were included in this retrospective study. Four readers with different levels of experience independently read the CTAs in 2 separate sessions, with and without time-to-maximum of the tissue residue function maps, recording the presence or absence of an occlusion, diagnostic confidence, and interpretation time. Accuracy for detecting distal occlusions was assessed using receiver operating characteristic analysis, and areas under curves were compared to assess whether accuracy improved with use of time-to-maximum of the tissue residue function. Changes in diagnostic confidence and interpretation time were assessed using the Wilcoxon signed rank test.

RESULTS

Mean sensitivity for detecting occlusions on CTA increased from 70.7% to 90.4% with use of time-to-maximum of the tissue residue function maps. Diagnostic accuracy improved significantly for the 4 readers (P < .001), with areas under the receiver operating characteristic curves increasing by 0.186, 0.136, 0.114, and 0.121, respectively. Diagnostic confidence and speed also significantly increased.

CONCLUSIONS

All assessed metrics of diagnostic performance for detecting distal arterial occlusions improved with the use of time-to-maximum of the tissue residue function maps, encouraging their use to aid in interpretation of CTA by both experienced and inexperienced readers. These findings show the added diagnostic value of including CTP in the acute stroke imaging protocol.

Mechanical thrombectomy with a novel device: initial clinical experience with the ANA thrombectomy device

INTRODUCTION

The ANA™ (Anaconda Biomed) thrombectomy system is a novel stroke thrombectomy device comprising a self-expanding funnel designed to reduce clot fragmentation by locally restricting flow while becoming as wide as the lodging artery. Once deployed, ANA allows distal aspiration in combination with a stentretriever (SR) to mobilize the clot into the funnel where it remains copped during extraction. We investigate safety and efficacy of ANA™ in a first-in-man study.

METHODS

Prospective data was collected on 35 consecutive patients treated as first line with ANA™ at a single centre. Outcome measures included per-pass reperfusion scores, symptomatic intracerebral hemorrhage (sICH), NIHSS at day 5, and mRS at 90 days.

RESULTS

Median NIHSS was 12(9-18). Sites of primary occlusion were: 5 ICA, 15 M1-MCA, 15 M2-MCA. Primary performance endpoint, mTICI 2b-3 within 3 passes without rescue therapy was achieved in 91.4% (n = 32) of patients; rate of complete recanalization (mTICI 2c-3) was 65.7%. First pass complete recanalization rate was 42.9%, and median number of ANA passes 1(IQR: 1-2). In 17.1% (n = 6) rescue treatment was used; median number of rescue passes was 2(1-7), leading to a final mTICI2b-3rate of 94.3% (n = 33). There were no device related serious adverse events, and rate of sICH was 5.7% (n = 2). At 5 days median NIHSS was 1 (IQR 1-6) and 90 days mRS 0-2 was achieved in 60% of patients.

CONCLUSIONS

In this initial clinical experience, the ANA™ device achieved a high rate of complete recanalization with a good safety profile and favourable 90 days clinical outcomes.

Predictors and prognoses of Willisian collateral failure during mechanical thrombectomy

During mechanical thrombectomy in the anterior cerebral circulation, thrombus embolization resulting in Willisian collateral failure may lead to critical stroke outcomes due to a shutdown of leptomeningeal collaterals. We hypothesized that the outcomes of dynamic Willisian collateral failure (DWF), induced during mechanical thrombectomy, would be associated with grave outcomes. We evaluated this hypothesis in consecutive patients, between January 2011 and May 2016, who underwent mechanical thrombectomy for anterior circulation occlusions, with an onset-to-puncture of 24 h. Patients with initial Willisian collateral failure (IWF) were identified first, with remaining patients classified into the DWF and Willisian collateral sparing (WCS) groups. Comparative and multivariable analyses were performed to predict grave outcomes (3-month modified Rankin Scale score of 5–6). Among 567 patients, 37 were in the IWF group, 38 in the DWF group, and 492 in the WCS group. Compared to the WCS and DWF groups, the IWF group had a higher baseline National Institute of Health Stroke Scale score and lower Alberta Stroke Program Early CT Score. The prevalence of grave outcomes was similarly high in the IWF (48.6%) and DWF (47.4%) groups, but lower in the WCS group (22.0%; p < 0.001). IWF and DWF were independent risk factors for a grave outcome.

Quantitative Characterization of Recanalization and Distal Emboli with a Novel Thrombectomy Device

PURPOSE

The first-pass effect during mechanical thrombectomy improves clinical outcomes regardless of first-line treatment approach, but current success rates for complete clot capture with one attempt are still less than 40%. We hypothesize that the ThrombX retriever (ThrombX Medical Inc.) can better engage challenging clot models during retrieval throughout tortuous vasculature in comparison with a standard stent retriever without increasing distal emboli.

MATERIALS AND METHODS

Thrombectomy testing with the new retriever as compared to the Solitaire stent retriever was simulated in a vascular replica with hard and soft clot analogs to create a challenging occlusive burden. Parameters included analysis of distal emboli generated per clot type, along with the degree of recanalization (complete, partial or none) by retrieval device verified by angiography.

RESULTS

The ThrombX device exhibited significantly higher rates of first-pass efficacy (90%) during hard clot retrieval in comparison with the control device (20%) (p < 0.009), while use of both techniques during soft clot retrieval resulted in equivalent recanalization. The soft clot model generated higher numbers of large emboli (>200 μm) across both device groups (p = 0.0147), and no significant differences in numbers of distal emboli were noted between the ThrombX and Solitaire techniques.

CONCLUSIONS

Irrespective of clot composition, use of the ThrombX retriever demonstrated high rates of complete recanalization at first pass in comparison with a state-of-the-art stent retriever and proved to be superior in the hard clot model. Preliminary data suggest that risk of distal embolization associated with the ThrombX system is comparable to that of the control device.

Thrombectomy for acute ischemic stroke patients with isolated distal internal carotid artery occlusion: a retrospective observational study

Purpose

Acute stroke patients presenting with a distal internal carotid artery occlusion and patent carotid terminus, allowing for collateral flow via the circle of Willis, may have a more favorable natural history. Therefore, benefit of endovascular treatment (EVT) is less evident. We performed an exploratory analysis of EVT results compared to conservative treatment in patients with ‘carotid-I’ occlusions.

Methods

We report on EVT-treated and non-EVT-treated patients with carotid-I occlusions from the MR CLEAN Registry, MR CLEAN trial, and our comprehensive stroke center. CT-angiography was reviewed on primary collateral patency and choroid plexus enhancement. Perfusion deficits were assessed on CT-perfusion (CTP). Clot migration was assessed by comparing clot location on baseline CTA to its location on periprocedural digital subtraction angiography. Outcomes included 90-day functional independence (mRS 0–2), successful reperfusion and mortality.

Results

We included 51 patients. Forty-one patients received EVT, ten patients did not. Intravenous thrombolysis was administered in 32 (78%) EVT-treated patients and 6 (60%) non-EVT-treated patients. CTP, available for 17 patients, showed hypoperfusion on cerebral blood flow maps in 13 (76%) patients. Successful reperfusion after EVT occurred in 23 (56%), and clot migration in 8 patients (20%). Functional independence was achieved in 54% (21/39) of EVT-treated and in 10% (1/10) of non-EVT-treated patients. Mortality was 26% (10/39) and 30% (3/10), respectively. Anterior choroidal artery patency and choroid plexus enhancement were positively associated with functional independence.

Conclusion

In our population, data suggest improved outcomes after EVT in carotid-I occlusion patients and provide no arguments to withhold EVT in these patients.

Electronic supplementary material

The online version of this article (10.1007/s00234-020-02550-5) contains supplementary material, which is available to authorized users.

Standardized Fabrication Method of Human-Derived Emboli with Histologic and Mechanical Quantification for Stroke Research

BACKGROUND

As access to patient emboli is limited, embolus analogs (EAs) have become critical to the research of large vessel occlusion (LVO) stroke and the development of thrombectomy technology. To date, techniques for fabricating standardized human blood-derived EAs are limited in the variety of compositions, and the mechanical properties relevant to thrombectomy are not quantified.

METHODS

EAs were made by mixing human banked red blood cells (RBCs), plasma, and platelet concentrate in 10 different volumetric percentage combinations to mimic the broad range of patient emboli causing LVO strokes. The samples underwent histologic analysis and tensile testing to mimic the pulling action of thrombectomy devices, and were compared to patient emboli.

RESULTS

EAs had histologic compositions of 0-96% RBCs, 0.78%-92% fibrin, and 2.1%-22% platelets, which can be correlated with the ingredients using a regression model. At fracture, EAs elongated from 81% to 136%, and the ultimate tensile stress ranged from 16 to 949 kPa. These EAs' histologic compositions and tensile properties showed great similarity to those of emboli retrieved from LVO stroke patients, indicating the validity of such EA fabrication methods. EAs with lower RBC and higher fibrin contents are more extensible and can withstand higher tensile stress.

CONCLUSIONS

EAs fabricated and tested using the proposed new methods provide a platform for stroke research and pre-clinical development of thrombectomy devices.

Infarct in new territory after endovascular stroke treatment: A diffusion-weighted imaging study

Data on infarcts in new territory (INT) in patients undergoing endovascular stroke treatment for acute large-vessel occlusions are sparse. Aim of this study was to assess the prevalence, risk factors, and clinical relevance of INT. For this purpose, all patients in a single-center prospective registry who underwent endovascular stroke treatment and received pre- and post-interventional diffusion-weighted imaging were included (N = 259). Using an established scoring system, INT were classified according to size (I-III, ≤2 mm, >2 mm ≤20 mm, >20 mm) and likelihood of being related to the intervention (A, high likelihood; B, low likelihood). Additionally, a new type of infarct, that occurred in a territory distal to the occlusion, but was initially not hypoperfused, was defined as an infarct in initially not hypoperfused territory (IINHT). A total of 180 INT and 38 IINHT were observed in 32.8% (N = 85/259) of patients. In most patients, INT were angiographically occult (90.2%), and 13 patients had INT/IINHT larger than 2 cm (type III). Absence of protection during stent-retrieval and a cardio-embolic stroke origin were associated with higher incidence of INT/IINHT, whereas pretreatment with IV tPA showed no association, even when different bolus timing was considered. INT/IINHT were associated with lower rates of functional independence with increasing size type after adjusting for confounders (adjusted Odds Ratio per size group increase 0.63, 95% confidence interval 0.46-0.86). In conclusion, INT and IINHT are not rare, are associated with poor outcome with increasing size, and they may serve as a surrogate endpoint for safety evaluation of new devices and endovascular techniques. Further research on associated factors is warranted.

Insights Into Intra-arterial Thrombolysis in the Modern Era of Mechanical Thrombectomy

Background and Purpose: The role of intra-arterial (IA) thrombolysis in modern endovascular therapy is not well-understood. Here, we surveyed neurointerventionalists to understand their current clinical practices and opinions of IA thrombolysis in the new era of mechanical thrombectomy (MT).

Method: A 24-question anonymous survey was distributed via email to the members of the Society of Vascular and Interventional Neurology.

Results: One hundred and four responses were included in the analysis. Most respondents were interventional neurologists (76.9%) and had ≥5-years in neuro-interventional practice (80.8%). IA thrombolytics are presently used by 60.6%. Aspiration plus stent-retriever was the most common MT approach used with IA-thrombolysis (66.0%). IA-thrombolysis was used in mainly three approaches: (1) treatment of primary distal occlusions, (2) as rescue after proximal occlusion thrombectomy, and (3) or as adjunct therapy to primary MT approach. The most frequent IA-rtPA dose was 3–10 mg, with 1 mg/min infusion rate (56.6%). 84.9% do not have a standardized protocol for administering IA-rtPA. About half (50.9%) believed there should be no time limit for administering IA lytic if there is a favorable imaging profile, while 30.2% indicated ≤6 h. Most respondents (76.5%) would consider using IA-tenecteplase in a trial setting. Only 12.9% felt there was no role for IA thrombolysis in modern endovascular practice. Respondents with ≥10-years' experience were less supportive of the future of IA lytic (98.0 vs. 76.4%, p = 0.006).

Conclusion: IA-thrombolysis is currently used in clinical practice; however, there is no clear consensus on best practices or criteria for administration. Further studies are needed to define the role of IA-thrombolysis in the context of MT.

Mechanical Thrombectomy of Primary Distal Anterior Cerebral Artery Occlusion: A Case Report

Objective

Primary anterior cerebral artery (ACA) occlusion is a rare condition and sometimes leads to significant neurological deficits. We herein report on the efficacy of mechanical thrombectomy (MT) in treating the distal ACA occlusion in a clinical setting.

Case Presentation

A 76-year-old woman presented with a sudden onset of right hemiparesis. Computed tomographic angiography and perfusion imaging and subsequent analysis with RAPID software revealed acute left ACA occlusion with salvageable penumbra. The patient obtained a score of 11 on the National Institutes of Health Stroke Scale. MT was performed for occlusion of the left ACA (A4), and successful reperfusion (Thrombolysis in Cerebral Infarction score of 3) was achieved on the first attempt using a stent retriever. The patient's recovery progressed well, and she was discharged 13 days after admission with a modified Rankin Scale score of 1.

Conclusion

This case report demonstrates the clinical efficacy, safety, and favorable clinical outcome of treating a primary distal ACA occlusion with MT.

Iodine-stained fragmented thromboembolism

AIM

Iodine-stained fragmented thromboembolism (ISFT) is a rare phenomenon encountered in the immediate aftermath of mechanical thrombectomy or rarely as a complication of post-carotid stenting. The aim was to describe the imaging appearance and discuss its pathophysiology.

METHOD

This is a retrospective review of patients who underwent mechanical thrombectomy for acute stroke at a single institution over the period of one year. All patients underwent the standard acute stroke imaging protocol (CT head, CT angiogram (CTA) and CT brain perfusion) and when clinically appropriate followed by catheter angiogram and mechanical thrombectomy. ISFT was defined as an arterial luminal filling defect with Hounsfield density equal to or greater than iodine seen on the biplanar CT or conventional CT. The presence and location of ISFT were documented. Standard CT angiogram (CTA) or magnetic resonance angiogram (MRA) was performed 24-48 hours after the neurointerventional procedure to assess for recanalization, volume of infarction and the fate of the ISFT.

RESULTS

ISFTs were identified in eight (five males and three females, age range 18-80 years) out of 49 patients in the following locations: distal M1 (n = 1), M2 (n = 4), M3 (n = 1), A1 (n = 1), distal A2 (n = 1). ISFT and vessel recanalization occurred in five patients on follow-up. ISFT and vessel occlusion persisted in two patients.

CONCLUSION

ISFT is likely the result of mechanical disruption of a thromboembolus, and porosity of the thromboembolus fragment may transiently retain iodinated contrast. Recognition of this entity may be important to aid detection of residual thromboembolism and avoid misinterpretation as calcified thromboembolism.

The Effects of Balloon-Guide Catheters on Outcomes after Mechanical Thrombectomy in Acute Ischemic Strokes : A Meta-Analysis

Objective

Mechanical thrombectomies with balloon-guide catheters (BGC) are thought to improve successful recanalization rates and to decrease the incidence of distal emboli compared to thrombectomies without BGC. We aimed to assess the effects of BGC on the outcomes of mechanical thrombectomy in acute ischemic strokes.

Methods

Studies from PubMed, EMBASE, and the Cochrane library database from January 2010 to February 2018 were reviewed. Random effect model for meta-analysis was used. Analyses such as meta-regression and the “trim-and-fill” method were additionally carried out.

Results

A total of seven articles involving 2223 patients were analyzed. Mechanical thrombectomy with BGC was associated with higher rates of successful recanalization (odds ratio [OR], 1.632; 95% confidence interval [CI], 1.293–2.059). BGC did not significantly decrease distal emboli, both before (OR, 0.404; 95% CI, 0.108–1.505) and after correcting for bias (adjusted OR, 1.165; 95% CI, 0.310–4.382). Good outcomes were observed more frequently in the BGC group (OR, 1.886; 95% CI, 1.564–2.273). Symptomatic intracranial hemorrhage and mortality did not differ significantly with BGC use.

Conclusion

Our meta-analysis demonstrates that BGC enhance recanalization rates. However, BGC use did not decrease distal emboli after mechanical thrombectomies. This should be interpreted with caution due to possible publication bias and heterogeneity. Additional meta-analyses based on individual patient data are needed to clarify the role of BGC in mechanical thrombectomies.

Beyond Large Vessel Occlusion Strokes: Distal Occlusion Thrombectomy

BACKGROUND AND PURPOSE

Endovascular therapy is the standard of care for the treatment of proximal large vessel occlusion strokes. Its safety and efficacy in the treatment of distal intracranial occlusions has not been well studied.

METHODS

The data that support the findings of this study are available from the corresponding author on reasonable request. Retrospective review of a prospectively collected endovascular database (2010-2015, n=949) for all patients with distal intracranial occlusions treated endovascularly. Distal occlusions were defined as any segment of the anterior cerebral artery (ACA), posterior cerebral artery, or occlusion at or distal to the middle cerebral artery (MCA)-M3 opercular segment.

RESULTS

Distal occlusions were treated in 69 patients. The mean age was 66.7±15.8 and 57% were male. Patients (29 [42%]) received intravenous tPA (tissue-type plasminogen activator). The median preprocedure National Institutes of Health Stroke Scale score was 18 (interquartile range, 13-23). The distal occlusion was the primary treatment location in 45 patients, in 23 patients the distal occlusion was treated as a rescue strategy after successful treatment of a proximal large vessel occlusion strokes, and 1 patient had both primary and rescue treatment. The locations of the primary cases were MCA-M3 (n=21), ACA alone (n=8), ACA with a concomitant MCA-M1 or MCA-M2 (n=10), ACA with a concomitant MCA-M3 (n=3), and posterior cerebral artery (n=3). The locations of the rescue cases were MCA-M3 (n=11), ACA (n=7), posterior cerebral artery (n=4), and both MCA-M3 and ACA (n=1). There was a single patient with primary ACA and MCA-M2 occlusions treated, who then had a rescue MCA-M3 thrombectomy addressed after initial reperfusion. The most common treatment modalities used were stent-retrievers (n=37, 54%), intra-arterial tPA (n=36, 52%), and thromboaspiration (n=31, 45%). Near complete or complete reperfusion of the distal territory (modified Treatment In Cerebral Ischemia [mTICI] 2b-3) was achieved in 57 cases (83%). Three parenchymal hematomas (4%) occurred in the territory of the treated distal occlusion with 2 of these patients also receiving intravenous tPA. At 90 days, 21 patients (30%) had a modified Rankin Scale score of 0 to 2 and 14 (20%) had died.

CONCLUSIONS

Distal intracranial occlusions can be treated safely and successfully with endovascular therapy. These results need to be corroborated by larger prospective controlled studies.

Anterior cerebral artery embolism during thrombectomy increases disability and mortality

Objective

During thrombectomy, thromboembolic migration in previously unaffected territory may occur and is not systematically notified. We report our data on the incidence, predictors, and clinical outcome of anterior cerebral artery emboli (ACAE).

Methods

From a prospectively collected thrombectomy database of consecutive patients with anterior circulation stroke between January 2012 and December 2016, 690 angiographic images were analyzed to assess ACAE. The primary outcome was a favorable outcome, defined as a 3 month modified Rankin Scale score of 0–2 or equal to the pre-stroke score.

Results

ACAE occurred in 65 patients (9.4%; 95% CI 7.2% to 11.6%). Internal carotid artery occlusion (tandem or terminal), Alberta Stroke Program Early CT Score <7, increasing number of passes, and use of stent retriever alone (compared with distal aspiration alone or combined with stent retriever) were found to be independent predictors of ACAE. Compared with patients without ACAE, patients with ACAE had lower rates, with an adjusted OR (95% CI) of 0.48 (0.25 to 0.92; P=0.027) for favorable outcome and 0.49 (0.25 to 0.96; P=0.038) for early neurologic improvement. ACAE was significantly associated with a higher mortality (adjusted OR 1.93; 95% CI 1.03 to 3.61; P=0.039) and intracranial hemorrhagic complications (adjusted OR 2.45; 95% CI 1.33 to 4.47; P=0.004). Despite a successful reperfusion modified Thrombolysis in Cerebral Infarction score of 2b–3 at the end of the procedure, a favorable outcome was reached in 30% of patients with ACAE compared with 52.4% in the other patients (OR 0.39; 95% CI 0.19 to 0.78; P=0.008).

Conclusions

Procedural ACAE was not an uncommon condition, and was associated with increased mortality and disability rates, regardless of the success of reperfusion.

Posterior Circulation Occlusions May Be Associated with Distal Emboli During Thrombectomy : Factors for Distal Embolization and a Review of the Literature

Background

Distal embolization or movement of the thrombus to previously uninvolved vasculature are feared complications during stroke thrombectomy. We looked at associated factors in a consecutive series of patients who underwent thrombectomy with the same endovascular device.

Methods

We included all patients with acute ischemic stroke in the anterior or posterior circulation, who underwent thrombectomy with the same thrombectomy device for acute stroke from 2013 to 2016. Distal embolization was defined as any movement of the thrombus into a previously uninvolved portion of the cerebral vasculature or the presence of thrombotic material further downstream in the affected vessel, which occurred after the initial angiogram. We studied patient-related as well as technical factors to determine their association with distal emboli.

Results

In this study 167 consecutive acute stroke patients treated with the emboTrap® device (Cerenovus, Irvine, CA, USA) were included with a median National Institutes of Health Stroke Scale (NIHSS) of 15 (range 2–30) and mean age of 67 years (SD 13.1 years). Of the patients in our cohort 20 (11.9%) experienced distal emboli, with 2.3% into a new territory and 9.6% into a territory distal to the primary occlusion. On univariate analysis, age, intravenous tissue plasminogen activator (tPA), posterior circulation occlusions, and general anesthesia were associated with distal emboli. On multivariate analysis, only posterior circulation occlusions (odds ratio OR 4.506 95% confidence interval CI 1.483–13.692, p = 0.008) were significantly associated with distal emboli. Distal embolization was not significantly associated with worse functional outcomes at 3 months, increased mortality or increased bleeding risk.

Conclusion

Posterior circulation occlusions were significantly associated with distal emboli during thrombectomy, possibly due to the lack of flow arrest during such procedures. New techniques and devices should be developed to protect against embolic complications during posterior circulation stroke thrombectomy.

Novel Distal Emboli Protection Technology: The EmboTrap

Background

Over the course of the thrombectomy procedure, clot fragments may become dislodged and lead to downstream emboli due to manipulation of an endovascular device. The EmboTrap thrombectomy system features an inner stent channel with an outer stent trap design that may potentially reduce the risk of distal clot fragmentation during clot removal. We tested the hypothesis that distal emboli to both the same and new territory generated during mechanical thrombectomy are a function of device design.

Methods

EmboTrap and Solitaire thrombectomy were conducted in an in vitro model system that mimicked a middle-cerebral artery (MCA) occlusion within a complete circle of Willis vascular replica and a contrast-enhanced clot analog. Emboli generated during the procedure with a size >1,000 μm were collected and measured with calipers. The Coulter principle was used to characterize emboli with a size between 200 and 1,000 µm.

Results

EmboTrap thrombectomy resulted in a significant reduction in the risk of large emboli (>1,000 μm) formation as compared to first-generation stent retriever thrombectomy (p = 0.031, Fisher exact test). The majority of emboli >1,000 μm (∼80%) were found in the MCA, regardless of device type. There was no significant difference between the EmboTrap and Solitaire in 200 to 1,000 μm emboli formation (p = 0.89, Mann-Whitney test). When combining all emboli in the most dangerous range (>200 μm), EmboTrap offered a size reduction of emboli (p = 0.022).

Conclusion

The risk of distal embolization can be altered with improved stent retriever design. When encountering fragment-prone clots, EmboTrap thrombectomy may lower the risk of distal embolization.

Manual aspiration thrombectomy with a Penumbra catheter for acute anterior cerebral artery occlusion

Purpose The purpose of this article is to assess the efficacy and safety of manual aspiration thrombectomy (MAT) using a Penumbra catheter in patients with anterior cerebral artery (ACA) occlusions. Materials and methods From January 2012 to March 2016, 16 patients underwent MAT with Penumbra catheters using a proximal and distal supporting technique to treat ACA occlusions. We evaluated immediate angiographic results and clinical outcomes by reviewing patient electrical medical records. Results Of these patients, 11 had a complete obstruction of the distal internal carotid artery (ICA) and five had ACA and middle cerebral artery (MCA) occlusions. All patients achieved successful recanalization of the distal ICA or MCA (Thrombolysis in Cerebral Infarction (TICI) grade ≥2b). Overall the recanalization rate for ACA occlusions (TICI grade≥2b) was 93.7% (15/16). The median procedure time was 45 minutes (range: 35-65 minutes). No patients were observed to have a procedure-related subarachnoid hemorrhage. Four patients (25.0%) died during hospitalization because of massive symptomatic hemorrhage, brain edema, or herniation. At discharge, the median NIHSS score for surviving patients was 6 (range: 1-17). Five patients had favorable clinical outcomes (modified Rankin scale ≤2). Conclusion MAT appears to be safe and successfully achieves recanalization in patients with ACA occlusions.

Efficacy of Balloon-Guiding Catheter for Mechanical Thrombectomy in Patients with Anterior Circulation Ischemic Stroke

Objective

To evaluate the efficacy of balloon guiding catheter (BGC) during thrombectomy in anterior circulation ischemic stroke.

Methods

Sixty-two patients with acute anterior circulation ischemic stroke were treated with thrombectomy using a Solitaire stent from 2011 to 2016. Patients were divided into the BGC group (n=24, 39%) and the non-BGC group (n=38, 61%). The number of retrievals, procedure time, thrombolysis in cerebral infarction (TICI) grade, presence of distal emboli, and clinical outcomes at 3 months were evaluated.

Results

Successful recanalization was more frequent in BGC than in non-BGC (83% vs. 66%, p=0.13). Distal emboli occurred less in BGC than in non-BGC (23.1% vs. 57.1%, p=0.02). Good clinical outcome was more frequent in BGC than in non-BGC (50% vs. 16%, p=0.03). The multivariate analysis showed that use of BGC was the only independent predictor of good clinical outcome (odds ratio, 5.19: 95% confidence interval, 1.07–25.11). More patients in BGC were successfully recanalized in internal carotid artery (ICA) occlusion with small retrieval numbers (<3) than those in non-BGC (70% vs. 24%, p=0.005). In successfully recanalized ICA occlusion, distal emboli did not occur in BGC, whereas nine patients had distal emboli in non-BGC (0% vs. 75%, p=0.001) and good clinical outcome was superior in BGC than in non-BGC (55.6% vs. 8.3%, p=0.01).

Conclusion

A BGC significantly reduces the number of retrievals and the occurrence of distal emboli, thereby resulting in better clinical outcomes in patients with anterior circulation ischemic stroke, particularly with ICA occlusion.

Wire escalation in emergent revascularization procedures of internal carotid artery occlusions: the use of high tip stiffness microguidewires

Objective

We examined the usefulness and safety of high tip stiffness cardiac microguidewires in the endovascular revascularization of selected cases of internal carotid artery (ICA) occlusion.

Methods

Files of patients with acute ischemic symptoms due to ICA occlusions managed from August 2010 to August 2016 by urgent endovascular revascularization were retrospectively reviewed with a waiver of informed consent. Cases where there was escalation to stiff tipped cardiovascular microguidewires after at least two failed attempts to cross the carotid occlusion with standard neuro-microguidewires were included. Radiological and interventional data were recorded.

Results

63 patients with acute carotid occlusions underwent emergent endovascular revascularization in the study period; 5/63 patients met the inclusion criteria. In 4/5 patients, there was no angiographic evidence of the remnant origin of the ICA; in 1/5 there was a wide round shaped proximal calcified cap that precluded soft guidewire entry. In all cases, antegrade wiring was achieved only after switching to stiffer guidewires designed for the management of chronic cardiac occlusions. The use of these stiffer tip wires was considered of critical importance in achieving the successful performance of the ICA revascularization procedure. In all patients, revascularization was achieved, and 90 day modified Rankin Scale score ranged from 0 to 2.

Conclusions

When regular neuro-guidewires do not allow antegrade wiring in cases of ICA occlusion, wire escalation to high tip stiffness guidewires may improve success. These wires, designed to deal with chronic total coronary occlusions, can serve as a platform for new neuro-guidewires to be used in the challenging field of resistant supra-aortic occlusions.

[Mechanical thrombectomy: Acute complications and delayed sequelae]

BACKGROUND

Due to the positive evidence for mechanical thrombectomy (mTE), it will be increasingly used in future. Profound knowledge of potential complications, prevention and management of complications is necessary to safely implement mTE into clinical practice.

AIM

Description of specific complications of mTE and their clinical relevance, measures for prevention and management. Summary of the current knowledge on long-term side effects of mTE.

MATERIAL AND METHODS

Analysis of current trial results and selected case series to address specific topics. Summary of own practical clinical experience.

RESULTS

Vascular injury (1-5%) and emboli (5-9%) are the most relevant intraprocedural complications but the clinical outcome is variable. Measures for prevention and management are described in detail. Vasospasms frequently occur (20-26%) but rarely need specific treatment and do not affect the clinical course. In the case of restrictive indications the frequency of symptomatic hemorrhage is similar to that for medicinal treatment (up to 8%). Contrast medium enhancement in the area of the infarction on post-treatment imaging should not be mistaken for hemorrhages. Focal subarachnoid contrast medium enhancement or hemorrhage occurs in up to 24% of cases and is predominantly benign. In follow-up imaging stenoses or occlusions can be detected in 4-10% of the treated vessels, most of which are asymptomatic. They are considered to be caused by microtrauma to the vascular wall.

CONCLUSION

Clinically relevant complications of mTE are rare. Preventive measures and effective management of complications may even increase safety. Stenoses occasionally occur as a long-term side effect but are asymptomatic in the majority of cases.