Autonomous navigation of catheters and guidewires in mechanical thrombectomy using inverse reinforcement learning

PURPOSE

Autonomous navigation of catheters and guidewires can enhance endovascular surgery safety and efficacy, reducing procedure times and operator radiation exposure. Integrating tele-operated robotics could widen access to time-sensitive emergency procedures like mechanical thrombectomy (MT). Reinforcement learning (RL) shows potential in endovascular navigation, yet its application encounters challenges without a reward signal. This study explores the viability of autonomous guidewire navigation in MT vasculature using inverse reinforcement learning (IRL) to leverage expert demonstrations.

METHODS

Employing the Simulation Open Framework Architecture (SOFA), this study established a simulation-based training and evaluation environment for MT navigation. We used IRL to infer reward functions from expert behaviour when navigating a guidewire and catheter. We utilized the soft actor-critic algorithm to train models with various reward functions and compared their performance in silico.

RESULTS

We demonstrated feasibility of navigation using IRL. When evaluating single- versus dual-device (i.e. guidewire versus catheter and guidewire) tracking, both methods achieved high success rates of 95% and 96%, respectively. Dual tracking, however, utilized both devices mimicking an expert. A success rate of 100% and procedure time of 22.6 s were obtained when training with a reward function obtained through 'reward shaping'. This outperformed a dense reward function (96%, 24.9 s) and an IRL-derived reward function (48%, 59.2 s).

CONCLUSIONS

We have contributed to the advancement of autonomous endovascular intervention navigation, particularly MT, by effectively employing IRL based on demonstrator expertise. The results underscore the potential of using reward shaping to efficiently train models, offering a promising avenue for enhancing the accessibility and precision of MT procedures. We envisage that future research can extend our methodology to diverse anatomical structures to enhance generalizability.

Combined Aspiration and Stent Retriever Thrombectomy for Distal Carotid Artery Occlusion Using Balloon Guide versus Non-Balloon Guide Catheter

Background: The introduction of endovascular thrombectomy dramatically changed acute stroke management and became the standard treatment. Balloon guide catheters provide flow arrest during the clot retrieval process and have several advantages.This study aimed to compare balloon guide catheters (BGCs) versus non-balloon guide catheters (NBGCs) as a part of a combined treatment modality in patients presenting with acute ischemic stroke. Methods: This retrospective study included n = 65 patients who underwent a combined endovascular stroke treatment for distal internal carotid artery (ICA) occlusion. Patients underwent aspiration and stent retriever thrombectomy with the use of BGCs (Group 1, n = 27) or NBGCs (Group 2, n = 38). Results: The groups were compared for outcomes: the National Institutes of Health Stroke Scale (NIHSSS) score change, successful recanalization, good functional outcome at three months, and in-hospital mortality. Conclusion: The two groups didn't differ in terms of the NIHSS score change compared to baseline (p > 0.05). Moreover, there were no significant differences between the two groups in terms of the successful recanalization rate, three-month favorable functional outcome rate, and in-hospital mortality (p = 0.292, p = 0.952, p = 0.178), respectively. Further prospective studies with a larger number of patients and better methodology are warranted.

Outcomes of mechanical thrombectomy in orally anticoagulated patients with anterior circulation large vessel occlusion: a propensity-matched analysis of the Imperial College Thrombectomy Registry

BACKGROUND

Mechanical thrombectomy (MT) remains an effective treatment for patients with acute ischemic stroke receiving oral anticoagulation (OAC) and large vessel occlusion (LVO). However, to date, it remains unclear whether MT is safe in patients on treatment with OAC.

AIMS

In our study, we performed a propensity-matched analysis to investigate the safety and efficacy of MT in patients with acute ischemic stroke receiving anticoagulants. A propensity score method was used to target the causal inference of the observational study design.

METHODS

This observational, prospective, single-centre study included consecutive patients with acute LVO ischemic stroke of the anterior circulation. Demographic, neuro-imaging and clinical data were collected and compared according to the anticoagulation status at baseline, patients on OAC vs those not on OAC. The primary study outcomes were the occurrence of any intracerebral haemorrhage (ICH) and symptomatic ICH. The secondary study outcomes were functional independence at 90 days after stroke (defined as modified Rankin Scale (mRS) scores of 0 through 2), mortality at 3 months and successful reperfusion rate according to the modified treatment in cerebral infarction (mTICI) score.

RESULTS

Overall, our cohort included 573 patients with acute ischemic stroke and LVO treated with MT. After propensity score matching, 495 patients were matched (99 OAC group vs 396 no OAC group). There were no differences in terms of clinical characteristics between the two groups, except for the rate of intravenous thrombolysis less frequently given in the OAC group. There was no significant difference in terms of the rate of any ICH and symptomatic ICH between the two groups. With regards to the secondary study outcome, there was no significant difference in terms of the rate of successful recanalization post-procedure and functional independence at 3 months between the two groups. Patients in the OAC group showed a reduced mortality rate at 90 days compared to the patients with no previous use of anticoagulation (20.2% vs 21.2%, p = 0.031). Logistic regression analysis did not reveal a statistically significant influence of the anticoagulation status on the likelihood of any ICH (OR = 0.95, 95% CI = 0.46-1.97, p = 0.900) and symptomatic ICH (OR = 4.87, 95% CI = 0.64-37.1, p = 0.127). Our analysis showed also that pre-admission anticoagulant use was not associated with functional independence at 90 days after stroke (OR = 0.76, 95% CI = 0.39-1.48, p = 0.422) and rate of successful reperfusion (OR = 0.81, 95% CI = 0.38-1.72, p = 0.582).

CONCLUSION

According to our findings anticoagulation status at baseline did not raise any suggestion of safety and efficacy concerns when MT treatment is provided according to the standard guidelines. Confirmation of these results in larger controlled prospective cohorts is necessary.

Safety of Mechanical Thrombectomy in Patients on Antiplatelet/Anticoagulation

BACKGROUND

Mechanical thrombectomy (MT) is performed in patients who are already on anticoagulation (AC)/antiplatelet therapy (AP). However, data are insufficient regarding MT's safety and efficacy profiles in these patients.

OBJECTIVE

Investigate the outcome of stroke patients already on anticoagulation/antiplatelet receiving MT.

METHODS

We included consecutive acute ischemic stroke patients treated with MT for 10 years (2012-2022) in a comprehensive stroke center. Baseline variables, efficacy (recanalization [Thrombolysis in Cerebral Infraction] ≥ 2b), good functional outcome (modified Ranking Scale ≤ 2 at 3 months), and safety (symptomatic intracranial hemorrhage [sICH], mortality rates) were evaluated. Additionally, we conducted a subgroup analysis of patients with prior single-AP versus DAPT.

RESULTS

Six hundred forty-six patients were included (54.5% women, median age 71 years), 84 (13%) were on AC, 196 (30.3%) on AP, and 366 (56.7%) in the control group. The AC and AP groups were older and had more comorbidities. sICH occurred in 7.3% of cases. There was no significant difference in sICH incidence across the groups. The AC group had a lower rate of intravenous thrombolysis (15.9%; P < 0.001), a higher rate of sICH (11.9% vs. AP 7.7% and control 6%; P = 0.172), and higher mortality at discharge (17.9% vs. AP 8.7% and control 10.4%; P = 0.07). However, the groups had similar functional outcomes and mortality rates at 3 months. Successful recanalization was achieved in 92.7% and was similar across groups. Multivariable logistic regression and the subgroup analysis (single-AP vs. dual AP) did not reveal statistically significant associations.

CONCLUSIONS

MT in patients with prior anticoagulation and AP presenting with acute ischemic strokeis feasible, effective, and safe.

Safety of recanalization therapy in patients with acute ischemic stroke on direct oral anticoagulants: A sub-analysis of PASTA registry study

BACKGROUND

The safety of intravenous recombinant tissue plasminogen activator (rtPA) and mechanical thrombectomy (MT) in patients treated with direct oral anticoagulants (DOACs) before stroke has not been fully investigated. Therefore, we aimed to investigate the safety of recanalization therapy in patients receiving DOACs.

METHODS

We assessed data from a prospective multicenter registry of patients with stroke, including those with acute ischemic stroke (AIS) treated with rtPA and/or MT who were administered DOACs. We evaluated the safety of recanalization considering the DOACs dosage and interval between the last DOAC intake and recanalization.

RESULTS

The final analysis included 108 patients (women, n = 54; median age, 81 years; DOAC overdose, n = 7; appropriate dose, n = 74; and inappropriate low dose, n = 27). The rate of any ICH differed significantly among overdose-, appropriate dose-, and inappropriate-low dose DOACs groups (71.4, 23.0, and 33.3%, respectively; P = 0.0121), whereas no significant difference was observed in respect of symptomatic ICH (P = 0.6895). Multivariate analysis showed that the National Institutes of Health Stroke Scale score on admission (odds ratio [OR]: 1.06, 95% confidence interval [CI]: 1.01-1.11; P = 0.0267) and overdose-DOAC (OR: 8.40, 95% CI: 1.24-56.88; P = 0.0291) were independently associated with any ICH. No relationship was observed between the timing of the last DOAC intake and occurrence of ICH in patients treated with rtPA and/or MT (all P > 0.05).

CONCLUSION

Recanalization therapy during DOAC treatment may be safe in selected patients with AIS, if it is performed >4 h after the last DOAC intake and the patient is not overdosed with DOACs.

REGISTRATION

https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000034958.

Novel predictors and a predictive model of cerebrovascular atherosclerotic ischemic stroke based on clinical databases

BACKGROUND AND PURPOSE

Early identification of cerebrovascular atherosclerotic ischemic stroke is necessary for accurate treatment and clinical research.

AIMS

To identify novel predictors and build a predictive model of ischemic strokes due to cerebrovascular atherosclerosis.

METHOD

MIMIC-IV database was used to search for clinical data of patients with ischemic stroke. Included patients were divided into two groups according to their etiologies. Univariate and multivariate logistic regressions were used to build the predictive model, and the model reliability parameters were calculated. The cut-off value for the model was selected according to the Youden index. Clinical data from the Neurovascular Center of Changhai Hospital were used to verify the predictive model.

RESULTS

Logistical regressions showed a positive correlation between advanced age, peripheral atherosclerosis, history of transient ischemia, and the diagnosis of ischemic strokes due to cerebrovascular atherosclerosis. The history of atrial fibrillation, levels of the National Institutes of Health Stroke Scale, serum potassium, and activated partial thromboplastin time were negatively correlated to the diagnosis of cerebrovascular atherosclerotic ischemic stroke. The predictive model was constructed from logistic regression results, and the area under the curve was 0.764. The cut-off value for the model was set at 0.089 to achieve the highest Youden index, with sensitivity and specificity of 75.9% and 64.1%. Clinical verification of the model revealed that the sensitivity and specificity of the model were 52.5% and 93.0% respectively.

CONCLUSION

The efficacy of the predictive model was acceptable as an aid in predicting cerebrovascular atherosclerotic ischemic stroke.

Malnutrition risk and oropharyngeal dysphagia in the chronic post-stroke phase

Background

Oropharyngeal dysphagia (OD) and malnutrition are associated with poor clinical outcomes after stroke. The present study evaluated (1) malnutrition risk and OD-related characteristics in patients with chronic post-stroke OD, and (2) the relationship between on the one hand OD severity and on the other hand functional oral intake and dysphagia-specific quality of life.

Methods

A cross-sectional study was conducted in a Dutch interdisciplinary outpatient clinic for OD. The standardized examination protocol comprised: clinical ear, nose, and throat examination, body mass index, the short nutritional assessment questionnaire (SNAQ), a standardized fiberoptic endoscopic evaluation of swallowing (FEES), the functional oral intake scale (FOIS), and the MD Anderson dysphagia inventory (MDADI).

Results

Forty-two consecutive patients with chronic post-stroke OD were included. Mean (±SD) age and BMI of the population were 69.1 (±8.7) years and 26.8 (±4.1) kg/m2 respectively. Seventeen (40.4%) patients presented a moderate to high risk of malnutrition (SNAQ score≥2). The FEES examination showed moderate to severe OD in 28 (66.7%) patients. The severity of OD was significantly related to the FOIS score but not to the MDADI scores.

Conclusion

In this specific sample of referred stroke patients, moderate to severe OD and moderate to high risk of malnutrition were common. Despite the use of clinical practice guidelines on stroke and a normal nutritional status at first sight, repeated screening for malnutrition and monitoring the severity and management of OD remain important elements in the care of patients with chronic post-stroke OD.

Predictors of Symptomatic Hemorrhage After Endovascular Treatment for Anterior Circulation Occlusions: Turkish Endovascular Stroke Registry

We evaluated the predictive factors of symptomatic intracranial hemorrhage (SICH) in endovascular treatment of stroke. We included 975 ischemic stroke patients with anterior circulation occlusion. Patients that had hemorrhage and an increase of ≥4 points in their National Institutes of Health Stroke Scale (NIHSS) after the treatment were considered as SICH. The mean age of patients was 65.2±13.1 years and 469 (48.1%) were women. The median NIHSS was 16 (13-18) and Alberta Stroke Program Early CT 9 (8-10). In 420 patients (43.1%), modified Rankin Scale was favorable (0-2) and mortality was observed in 234 (24%) patients at the end of the third month. Patients with high diastolic blood pressure (P<.05) had significantly higher SICH. SICH was significantly higher in those with high NIHSS scores (P<.001), high blood glucose (P<.001), and leukocyte count at admission (P<.05). Diabetes mellitus (DM) (OR 1.90; P<.001), NIHSS (OR 1.07; P<.05), adjuvant intra-arterial thrombolytic therapy (IA-rtPA) (OR, 1.60; P<.05), and puncture-recanalization time (OR 1.01; P<.05) were independent factors of SICH. Higher baseline NIHSS score, longer procedure time, multiple thrombectomy maneuvers, administration of IA-rtPA, and the history of DM are independent predictors of SICH in anterior circulation occlusion.

Activation and Role of Astrocytes in Ischemic Stroke

Ischemic stroke refers to the disorder of blood supply of local brain tissue caused by various reasons. It has high morbidity and mortality worldwide. Astrocytes are the most abundant glial cells in the central nervous system (CNS). They are responsible for the homeostasis, nutrition, and protection of the CNS and play an essential role in many nervous system diseases’ physiological and pathological processes. After stroke injury, astrocytes are activated and play a protective role through the heterogeneous and gradual changes of their gene expression, morphology, proliferation, and function, that is, reactive astrocytes. However, the position of reactive astrocytes has always been a controversial topic. Many studies have shown that reactive astrocytes are a double-edged sword with both beneficial and harmful effects. It is worth noting that their different spatial and temporal expression determines astrocytes’ various functions. Here, we comprehensively review the different roles and mechanisms of astrocytes after ischemic stroke. In addition, the intracellular mechanism of astrocyte activation has also been involved. More importantly, due to the complex cascade reaction and action mechanism after ischemic stroke, the role of astrocytes is still difficult to define. Still, there is no doubt that astrocytes are one of the critical factors mediating the deterioration or improvement of ischemic stroke.

Performance feedback on the quality of care in hospitals performing thrombectomy for ischemic stroke (PERFEQTOS): protocol of a stepped wedge cluster randomized trial

Background

Although the provision of performance feedback to healthcare professionals based on data from quality registries is common practice in many fields of medicine, observational studies of its effect on the quality of care have shown mixed results. The objective of this study is to evaluate the effect of performance feedback on the quality of care for acute ischemic stroke.

Methods

PERFEQTOS is a stepped wedge cluster randomized trial in 13 hospitals in the Netherlands providing endovascular thrombectomy for ischemic stroke. The primary outcome is the hospital’s door-to-groin time. The study starts with a 6-month period in which none of the hospitals receives the performance feedback intervention. Subsequently, every 6 months, three or four hospitals are randomized to cross over from the control to the intervention conditions, until all hospitals receive the feedback intervention. The feedback intervention consists of a dashboard with quarterly reports on patient characteristics, structure, process, and outcome indicators related to patients with ischemic stroke treated with endovascular thrombectomy. Hospitals can compare their present performance with their own performance in the past and with other hospitals. The performance feedback is provided to local quality improvement teams in each hospital, who define their own targets on specific indicators and develop performance improvement plans. The impact of the performance feedback and improvement plans will be evaluated by comparing the primary outcome before and after the intervention.

Discussion

This study will provide evidence on the effectiveness of performance feedback to healthcare providers. The results will be actively disseminated through peer-reviewed journals, conference presentations, and various stakeholder engagement activities.

Trial registration

Netherlands Trial Register NL9090. Registered on December 3, 2020

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05819-z.

Ischaemic stroke in anticoagulated patients with atrial fibrillation

Anticoagulation substantially reduces the risk of stroke in patients with atrial fibrillation (AF). However, recent studies have shown that up to 22%-36% of patients on anticoagulation will suffer an ischaemic stroke (IS). In this narrative review, we provide an overview of risk factors, mechanisms, management of acute IS and strategies for secondary prevention for patients with AF with stroke despite oral anticoagulation. For this paper, we reviewed available literature from important studies (randomised clinical trials, meta-analyses, reviews and case series) on patients with IS despite anticoagulation. We focused on recent studies that examined safety and efficacy of acute stroke treatments and evaluation and management strategies for secondary prevention. The literature review suggests that patients with AF with IS despite anticoagulation are a heterogeneous group with several possible mechanisms, which may include reduced or non-adherence to anticoagulation, competing non-cardioembolic stroke aetiologies or cardioembolic mechanisms separate from AF. The identification of one or more possible mechanisms of stroke despite anticoagulation may allow for a more targeted and individualised approach for secondary prevention. There are limited data to guide management in such patients, and strategies to prevent recurrent strokes include strict risk factor control and therapies targeting the most likely stroke mechanism. In cases where AF is suspected to be the culprit, clinical trials are needed to test the safety and efficacy of left atrial appendage occlusion plus anticoagulation versus continued anticoagulation alone.

Mechanical thrombectomy with or without thrombolysis: A meta-analysis of RCTs

BACKGROUND

Mechanical thrombectomy (MT) is effective in treating ischemic strokes due to large vessel occlusion. However, the risk-benefit ratio of intravenous thrombolysis (IVT) prior to MT is still unclear. Aim of the study was to provide a pooled analysis of only randomized controlled trials (RCTs) comparing direct MT (dMT) vs bridging treatment (IVT+MT).

METHODS

PubMed, EMBASE and Cochrane Central were searched only for RCTs comparing IVT+MT vs dMT in ischemic stroke patients. Primary endpoint was functional independence at 90 days (mRS<3), while secondary endpoints were represented by successful recanalization (TICI>2a), mortality at 90 days and symptomatic intracranial hemorrhage (sICH). Odds ratios for endpoints were pooled with meta-analysis and compared between reperfusion strategies.

RESULTS

The pooled analysis comprised 5 studies (n. patients = 1657). The rates for the primary endpoint were 39% and 34.5% for dMT and IVT+MT, respectively (OR 1.06; 95%CI 0.80-1.40). For the secondary endpoints, we did not observe significant differences between groups, even if the rate of successful recanalization was higher in IVT+MT treated patients (OR: 0.58; 95%CI 0.26-1.30;p_{heterogeneity} = 0.002), without a significant increase in sICH rates (4.3% vs 5.5%; OR: 0.96; 95%CI 0.43-2.13;p_{heterogeneity} = 0.26). Finally, mortality rates were 19.8% and 15.9% for dMT and IVT+MT, respectively.

CONCLUSIONS

In this meta-analysis including only RCTs, dMT and bridging treatment were substantially equivalent for good functional outcome. IVT+MT was associated to higher rates of successful recanalization, even if not significant. Therefore, further adequately powered RCTs comparing dMT vs IVT+MT are warranted.

Endovascular treatment versus intravenous thrombolysis alone in isolated M2 occlusion: a meta-analysis

BACKGROUND

Optimal reperfusion strategies for M2 occlusion are still uncertain, with previous studies questioning benefit of mechanical thrombectomy (MT) over intravenous thrombolysis alone (IVT). Here we systematically reviewed and meta-analyzed data from studies comparing IVT alone vs MT with/without previous IVT, to define risk/benefit profile of each paradigm.

METHODS

The study followed PRISMA guidelines. PubMed, EMBASE, and Cochrane Central were searched only for RCTs comparing MT with or without IVT vs IVT alone in adults with acute ischemic stroke and M2 occlusion. Primary endpoint was functional independence at 90 days (modified Rankin Scale<3); secondary endpoints were represented by symptomatic intracranial hemorrhage (sICH) and good recanalization (TICI>2a). Odds ratios for endpoints were pooled with meta-analysis and compared between reperfusion strategies.

RESULTS

Seven studies (n=779) were included, all of high quality. Rate of good functional outcome was similar for MT and IVT (62.4% vs 66.3%; OR=0.73; 95%CI: 0.38-1.41; p_{heterogeneity}=0.008) (Fig. 1).sICH was significantly more frequent in the MT group (8.5%) vs IVT group (3%) (OR 2.76, 95%CI 1.19-6.36, p_{heterogeneity}=0.14). Good recanalization (TICI>2a) rate was higher in MT group vs IVT alone group (81.2% vs 51.4%; OR 3.99; 95%CI: 1.98-8.94; p_{heterogeneity}=0.80).

CONCLUSIONS

IVT alone provides similar clinical benefit compared to MT with/without IVT in cases of M2 occlusion. MT quadruplicates rates of good recanalization, but triplicates risk of sICH. Further trials are needed to define if MT confers any advantage over IVT for M2 occlusion.

Exosomes containing miR-451a is involved in the protective effect of cerebral ischemic preconditioning against cerebral ischemia and reperfusion injury

Aim

To study the role of exosomes in the protective effect of cerebral ischemic preconditioning (cerebral‐IPC) against cerebral I/R injury.

Method

Mouse models of cerebral‐IPC and MCAO/R were established as described previously, and their behavioral, pathological, and proteomic changes were analyzed. Neuro‐2a subjected to OGD/R were treated with exosomes isolated from the plasma of sham‐operated and cerebral‐IPC mice. The differentially expressed miRNAs between exosomes derived from sham‐operated (S‐exosomes) and preconditioned (IPC‐exosomes) mice were identified through miRNA array, and their targets were identified through database search. The control and OGD/R cells were treated with the IPC‐exosomes, miRNA mimic or target protein inhibitor, and their viability, oxidative, stress and apoptosis rates were measured. The activated pathways were identified by analyzing the levels of relevant proteins.

Results

Cerebral‐IPC mitigated the cerebral injury following ischemia and reperfusion, and increased the number of plasma exosomes. IPC‐exosomes increased the survival of Neuro‐2a cells after OGD/R. The miR‐451a targeting Rac1 was upregulated in the IPC‐exosomes relative to S‐exosomes. The miR‐451a mimic and the Rac1 inhibitor NSC23766 reversed OGD/R‐mediated activation of Rac1 and its downstream pathways.

Conclusion

Cerebral‐IPC ameliorated cerebral I/R injury by inducing the release of exosomes containing miR‐451a.

Oral Anticoagulation and Risk of Symptomatic Hemorrhagic Transformation in Stroke Patients Treated With Mechanical Thrombectomy: Data From the Nordictus Registry

Introduction: We aimed to evaluate if prior oral anticoagulation (OAC) and its type determines a greater risk of symptomatic hemorrhagic transformation in patients with acute ischemic stroke (AIS) subjected to mechanical thrombectomy.

Materials and Methods: Consecutive patients with AIS included in the prospective reperfusion registry NORDICTUS, a network of tertiary stroke centers in Northern Spain, from January 2017 to December 2019 were included. Prior use of oral anticoagulants, baseline variables, and international normalized ratio (INR) on admission were recorded. Symptomatic intracranial hemorrhage (sICH) was the primary outcome measure. Secondary outcome was the relation between INR and sICH, and we evaluated mortality and functional outcome at 3 months by modified Rankin scale. We compared patients with and without previous OAC and also considered the type of oral anticoagulants.

Results: About 1.455 AIS patients were included, of whom 274 (19%) were on OAC, 193 (70%) on vitamin K antagonists (VKA), and 81 (30%) on direct oral anticoagulants (DOACs). Anticoagulated patients were older and had more comorbidities. Eighty-one (5.6%) developed sICH, which was more frequent in the VKA group, but not in DOAC group. OAC with VKA emerged as a predictor of sICH in a multivariate regression model (OR, 1.89 [95% CI, 1.01–3.51], p = 0.04) and was not related to INR level on admission. Prior VKA use was not associated with worse outcome in the multivariate regression model nor with mortality at 3 months.

Conclusions: OAC with VKA, but not with DOACs, was an independent predictor of sICH after mechanical thrombectomy. This excess risk was associated neither with INR value by the time thrombectomy was performed, nor with a worse functional outcome or mortality at 3 months.

Current knowledge of large vascular occlusion due to intracranial atherosclerosis: focusing on early diagnosis

Intracranial atherosclerosis (ICAS)-related large vascular occlusion (LVO) was an intractable subtype of acute ischemic stroke (AIS), which always needed rescue angioplasty and stenting and complicated the procedure of endovascular recanalization. Diagnosing ICAS-LVO accurately and early was helpful for both clinical treatment and trials. Digital subtraction angiography (DSA) was unable to provide an early and rapid diagnosis of ICAS-LVO based on current studies. A variety of pre-DSA methods had been used to distinguish ICAS-LVO with other subtypes of ischemic stroke, such as medical histories, clinical presentations, computed tomography or angiography (CT/CTA), and magnetic resonance imaging (MRI/MRA). This article briefly reviewed the status quo of the diagnosis and treatment of ICAS-LVO and summarized early diagnostic methods of ICAS-LVO from different aspects.

Mothership versus Drip-and-Ship Model for Mechanical Thrombectomy in Acute Stroke: A Systematic Review and Meta-Analysis for Clinical and Radiological Outcomes

Background and Purpose

Substantial uncertainty exists on the benefit of organizational paradigms in stroke networks. Here we systematically reviewed and meta-analyzed data from studies comparing functional outcome between the mothership (MS) and the drip and ship (DS) models.

Methods

The meta-analysis protocol was registered international prospective register of systematic reviews (PROSPERO) and followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. PubMed, EMBASE, and Cochrane Central databases were searched for randomized-controlled clinical trials (RCTs), retrospective and prospective studies comparing MS versus DS. Primary endpoints were functional independence at 90 days (modified Rankin Scale <3) and successful recanalization (Thrombolysis in Cerebral Infarction Scale [TICI] >2a); secondary endpoints were 3-month mortality and symptomatic intracranial haemorrhage (sICH). Odds ratios for endpoints were pooled using the random effects model and were compared between the two organizational models.

Results

Overall, 18 studies (n=7,017) were included in quantitative synthesis. MS paradigm was superior to DS model for functional independence (odds ratio, 1.34; 95% confidence interval, 1.16 to 1.55; I²=30%). Meta-regression analysis revealed association between onset-to-needle time and good functional outcome, with longer onset-to-needle time being detrimental. Similar rates of recanalization, sICH and mortality at 90 days were documented between MS and DS.

Conclusions

Patients with acute ischemic stroke eligible for reperfusion strategies might benefit more from MS paradigm as compared to DS. RCTs are needed to further refine best management taking into account logistics, facilities and resources.

Comparison of First-Pass Efficacy Among Four Mechanical Thrombectomy Techniques: A Single-Center Experience

BACKGROUND

First-pass efficacy (FPE) is an established marker of technical and clinical efficacy among mechanical thrombectomy (MT) techniques. It is unclear what the optimal approach is in achieving FPE. We present a single-center experience comparing rates of FPE among 2 MT techniques and evaluate the potential predictors of FPE among other outcomes.

METHODS

A single-center retrospective analysis was carried out of patients with consecutive large-vessel occlusion strokes (LVOS) of anterior circulation from September 2015 to April 2019 who underwent MT and for whom data were available on the status of FPE. Four MT techniques were identified: ADAPT (a direct first-pass aspiration), SrADAPT (stent retriever with aspiration), SRBG (stent retriever with balloon guide catheter), and STRAP (stent retriever-aspiration and proximal flow arrest). The primary outcome was FPE and secondary outcomes included the rate of successful reperfusion.

RESULTS

Among 226 patients with LVOS of the anterior circulation who underwent MT, data were available for 164 on FPE for the 4 MT techniques. SRBG was the most prevalent technique. No significant difference was found in rates of FPE among the 4 MT techniques (P = 0.332). No independent predictors of FPE were identified on multivariable analysis. STRAP had the highest rate of successful reperfusion compared with the other techniques (P = 0.049) and was the only independent predictor of that outcome (P = 0.027).

CONCLUSIONS

Among patients with LVOS of the anterior circulation, the rate of FPE did not differ among the 4 MT techniques. There were no predictors of FPE among the studied variables. STRAP was the only predictor of successful reperfusion.

Acute Neurological Deterioration in Large Vessel Occlusions and Mild Symptoms Managed Medically

Background and Purpose—

It is unclear which factors predict acute neurological deterioration in patients with large vessel occlusion and mild symptoms. We aim to evaluate the frequency, timing, and potential predictors of acute neurological deterioration ≥4 National Institutes of Health Stroke Scale (NIHSS) points in medically managed patients with large vessel occlusion and mild presentation.

Methods—

Single-center retrospective study of patients with consecutive minor stroke (defined as NIHSS score of ≤5 on presentation) and large vessel occlusion from January 2014 to December 2017. Primary outcome was acute neurological deterioration ≥4 NIHSS points during the hospitalization. Secondary outcomes included ΔNIHSS (defined as discharge minus admission NIHSS score).

Results—

Among 1133 patients with acute minor strokes, 122 (10.6%) had visible occlusions on computed tomography angiography/magnetic resonance angiography. Twenty-four (19.7%) patients had ≥4 points deterioration on NIHSS at a median of 3.6 (1–16) hours from arrival. No clinical or radiological predictors of acute neurological deterioration ≥4 NIHSS points were observed on multivariable analysis. Rescue endovascular thrombectomy was performed more often in the ones with acute neurological deterioration ≥4 NIHSS points compared with patients with no deterioration (54% versus 0%; P <0.001). Acute neurological deterioration ≥4 NIHSS points was associated with ΔNIHSS ≥4 points (33% versus 4.9%; P <0.01) and a trend toward lower independence rates at discharge (50% versus 70%; P =0.06) compared with the group with no deterioration. In patients with any degree of neurological worsening, patients who underwent rescue thrombectomy were more likely to be independent at discharge (73% versus 38%; P =0.02) and to have a favorable ΔNIHSS (−2 [−3 to 0] versus 0 [−1 to 6]; P =0.05) compared with the ones not offered rescue thrombectomy.

Conclusions—

Acute neurological deterioration ≥4 NIHSS points was observed in a fifth of patients with large vessel occlusion and mild symptoms, occurred very early in the hospital course, impacted functional outcomes, and could not be predicted by any of the studied clinical and radiological variables. Rescue thrombectomy was associated with improved clinical outcomes at discharge in patients with neurological deterioration.

MT in anticoagulated patients

Mechanical thrombectomy (MT) is one of the main treatments for acute ischemic stroke (AIS) in patients on effective anticoagulation. The use of direct oral anticoagulants (DOA) has increased, given their efficacy and safety profile compared to vitamin K antagonists (VKA). We compared procedural and clinical outcomes of MT in patients on DOA and VKA treatment before stroke onset. We analyzed 2 groups from the Endovascular Treatment in Ischemic Stroke prospective registry: patients on DOA and patients on VKA treated by MT without thrombolysis. Generalized linear mixed models including center as random effect were used to compare angiographic (rates of reperfusion at end of procedure, number of passes >2, procedural complications) and clinical (favorable and excellent outcome, 90-day all-cause mortality, and hemorrhagic complications) outcomes according to anticoagulation subgroups. Comparisons were adjusted for prespecified confounders (age, admission NIH Stroke Scale score) as well as for meaningful baseline between-group differences. Among 221 patients included, more DOA-treated patients (n = 115, 52%) achieved successful (modified Thrombolysis in Cerebral Infarction score [mTICI] 2b/3) or near complete (mTICI 2c/3) reperfusion at the procedure end than did VKA-treated patients, with an adjusted odds ratio (OR) for DOA vs VKA of 3.27 (95% confidence interval [CI], 1.40–7.65) and 2.00 (95% CI, 1.08–3.73), respectively. DOA-treated patients had a lower 90-day mortality risk with an adjusted OR of 0.47 (95% CI, 0.24–0.89) and a better excellent outcome OR of 2.40 (1.10–5.27). There was no significant between-group difference in hemorrhagic or procedural complications. The study highlights the benefits of DOA compared to VKA. Regarding mortality, excellent outcomes, and recanalization rate, DOA appears to provide a favorable setting for MT treatment in AIS.

Organizing Healthcare for Optimal Acute Ischemic Stroke Treatment

Stroke is a major health-care problem that represents a leading cause of death and also the top cause of disability in adulthood. In recent years there has been a significant paradigm shift in treatments for acute ischemic stroke to favor earlier reperfusion therapy, mainly using the systemic infusion of recombinant tissue plasminogen activator. Subsequent trials found that combining this treatment with endovascular therapy was effective in selected patients. The increased complexity of acute stroke treatments has resulted in a substantial reorganization of stroke care. This review reports on the evolution of acute ischemic stroke treatment and describes the main organizational models based on the hub-and-spoke system. The lack of evidence for comparisons of the effectiveness of different paradigms means that some decision-analysis models predicting the best organizational pathways are also reported, with a particular emphasis on the workflow timing in the prehospital and in-hospital settings. Major benchmarks and performance measures are also reported, focusing on the timing of interventions and rates of process indicators. Finally, future directions are illustrated, including using telemedicine for stroke, mobile stroke units, and artificial intelligence and automated machines to produce software for detecting large-vessel occlusion.

The Large ARtery Intracranial Occlusion Stroke Scale: A New Tool With High Accuracy in Predicting Large Vessel Occlusion

Objectives: The combination of systemic thrombolysis and mechanical thrombectomy is indicated in patients with ischemic stroke due to a large vessel occlusion (LVO) and these treatments are time-dependent. Rapid identification of patients with suspected LVO also in a prehospital setting could influence the choice of the destination hospital. Aim of this pilot study was to evaluate the predictive role of a new stroke scale for LVO, comparing it to other scores.

Patients and Methods: All consecutive patients admitted to our comprehensive stroke center with suspected ischemic stroke were studied with a CT angiography and 5 different stroke scales were applied. The Large ARtery Occlusion (LARIO) stroke scale consists of 5 items including the assessment of facial palsy, language alteration, grip and arm weakness, and the presence of neglect. A Receiving Operating Characteristic curve was evaluated for each stroke scale to explore the level of accuracy in LVO prediction.

Results: A total of 145 patients were included in the analysis. LVO was detected in 37.2% of patients. The Area Under Curve of the LARIO score was 0.951 (95%CI: 0.902–0.980), similar to NIHSS and higher than other scales. The cut-off score for best performance of the LARIO stroke scale was higher than 3 (positive predictive value: 77% and negative predictive value: 100%).

Conclusion: The LARIO stroke scale is a simple tool, showing high accuracy in detecting LVO, even if with some limitations due to some false positive cases. Its efficacy has to be confirmed in a pre-hospital setting and other centers.

Safety and Feasibility of Argatroban, Recombinant Tissue Plasminogen Activator, and Intra-Arterial Therapy in Stroke (ARTSS-IA Study)

BACKGROUND

A randomized trial of concurrent recombinant tissue-type plasminogen activator (r-tPA) + thrombin-inhibition with Argatroban in stroke patients recently demonstrated safety and signal of efficacy compared to r-tPA alone, but patients having endovascular therapy (EVT) were excluded. The current study intended to study feasibility and safety of concurrent r-tPA and Argatroban in patients undergoing EVT.

METHODS

We conducted a single-arm, feasibility, and safety study of patients that received standard-dose r-tPA, had intracranial large vessel occlusions, and underwent EVT within 6 hours of stroke onset. During r-tPA, a 100 μg/kg Argatroban bolus, followed by 12-hour infusion, targeted an activated Partial Thromboplastin Time (aPTT) 2.25 timesbaseline. Feasibility was defined as ability to combine treatments without EVT time-metric delays, compared to cotemporaneous r-tPA + EVT treatments. Safety was incidence of symptomatic intracerebral hemorrhage (sICH), systemic hemorrhage, or EVT complications.

RESULTS

All preplanned 10 patients were enrolled. Arterial occlusions were middle cerebral artery (n = 8), internal carotid artery (n = 1), and posterior cerebral artery (n = 1). All received Argatroban before EVT and completed infusions. There were no delays in time-metrics compared to nonstudy patients during the same period. Nine patients achieved excellent angiographic reperfusion (Thrombolysis In Cerebral Ischemia [TICI] ≥2b); with 7 complete (TICI = 3). There were no sICH, systemic hemorrhage, or EVT complications. At 90 days, 6 (60%) patients had a modified Rankin Scale of 0-2 and none died.

CONCLUSIONS

In patients treated with r-tPA and EVT, concomitant Argatroban is feasible, does not delay EVT provision, produces high rates of recanalization, is probably safe, and warrants further study.

Prehospital stroke scales and large vessel occlusion: A systematic review

BACKGROUND AND PURPOSE

Time sensitivity for pharmacological and mechanical arterial recanalization in acute ischemic stroke influences the choice of the reference hospital. The accurate selection and identification of patients with high probability of a large vessel occlusion (LVO) in the prehospital setting improve the rationalization of the transport in the more suitable centers. Aim of this analysis was to determine the diagnostic accuracy of prehospital stroke scales detecting LVO.

MATERIAL AND METHODS

Studies were searched into MEDLINE, EMBASE, and CINHAL databases between January 1990 and September 2017. Principal measurements of the meta-analysis were the overall accuracy level, sensitivity, and specificity of prehospital stroke scales.

RESULTS

Nineteen scoring systems were included in the analysis coming from 13 studies. A total of 9824 patients were considered. Although a higher heterogeneity was observed in the analysis, three scores showed better results in predicting a LVO (the stroke Vision, Aphasia, Neglect assessment, the National Institute of Health Stroke scale and the Los Angeles Motor Scale). We observed significant differences of overall accuracy only for scores including hemineglect as cortical neurological sign (P < .05).

CONCLUSIONS

This meta-analysis suggests that some prehospital scoring systems including cortical signs showed better accuracy to predict stroke due to LVO. However, the assessment of these signs could be difficult to investigate by paramedics and personnel of Emergency Medical Services, and for this reason, further prospective evaluations are needed.

Safety and efficacy of mechanical thrombectomy in acute ischemic stroke of anticoagulated patients

Background

Anticoagulated patients (APs) are currently excluded from acute ischemic stroke reperfusion therapy with intravenous recombinant tissue plasminogen activator (IV-rtPA); however, these patients could benefit from mechanical thrombectomy (MT). Evidence for MT in this condition remains scarce. The aim of this study was to analyze the safety and efficacy of MT in APs.

Methods

We analyzed three patient groups from two prospective registries: APs with MT (AP-MT group), non-anticoagulated patients treated with MT (NAP-MT group), and non-anticoagulated patients treated with IV-rtPA and MT (NAP-IVTMT group). Univariate and multivariate logistic regression were used to evaluate treatment efficacy with modified Rankin Scale (mRS) ≤2 and safety (radiologic intracranial hemorrhage (rICH), symptomatic intracranial hemorrhage (sICH) and death rate at 3 months) between groups.

Results

333 patients were included in the study, with 44 (12%) in the AP-MT group, 105 (31%) in the NAP-MT group, and 188 (57%) in the NAP-IVTMT group. Univariate analysis showed that the AP-MT group was older (P<0.001), more often had atrial fibrillation (P<0001), and had a higher ASPECTS (P<0.006 and P<0.002) compared with the NAP-MT group and NAP-IVTMT groups, respectively. Multivariate analysis showed that the AP-MT group had a lower risk of rICH (OR 2.77, 95% CI 1.01 to 7.61, P=0.05) but a higher risk of death at 3 months (OR 0.26, 95% CI 0.09 to 0.76, P=0.01) compared with the NAP-IVTMT group. No difference was found between the AP-MT and NAP-MT groups.

Conclusions

With regard to intracranial bleeding and functional outcome at 3 months, MT in APs seems as safe and efficient as in NAPs. However, there is a higher risk of death at 3 months in the AP-MT group compared with the NAP-IVTMT group.

Mechanical Thrombectomy in Strokes with Large-Vessel Occlusion Beyond 6 Hours: A Pooled Analysis of Randomized Trials

Background and Purpose

Mechanical thrombectomy with or without intravenous thrombolysis is indicated in the acute treatment of ischemic strokes caused by an emergent large-vessel occlusion (ELVO) within 6 hours from symptom onset. However, a significant proportion of patients are referred to comprehensive stroke centers beyond this therapeutic time window. This study performed a pooled analysis of data from trials in which mechanical thrombectomy was performed beyond 6 hours from symptom onset.

Methods

We searched for randomized controlled trials that compared mechanical thrombectomy with the best medical treatment beyond 6 hours for ischemic strokes due to ELVO and reported on between 1990 and April 2018. The intervention group comprised patients treated with mechanical thrombectomy. Statistical analysis was conducted while pooling data and analyzing fixed- or random-effects models as appropriate.

Results

Four trials involving 518 stroke patients met the eligibility criteria. There were 267 strokes treated with mechanical thrombectomy, with a median time of 10.8 hours between when the patient was last known to be well to randomization. We observed a significant difference between groups concerning the rate of functional independence at 90 days from stroke, with an absolute difference of 27.5% (odds ratio=3.33, 95% CI=1.81–6.12, p<0.001) and good recanalization (odds ratio=13.17, 95% CI=4.17–41.60, p<0.001) favoring the intervention group.

Conclusions

This meta-analysis confirms the efficacy of mechanical thrombectomy in selected ischemic stroke patients beyond 6 hours from symptom onset. The selection is mainly based on the limited core infarct detected by emergent assessment using neuroimaging techniques.