Ischemic Strokes Due to Large-Vessel Occlusions Contribute Disproportionately to Stroke-Related Dependence and Death: A Review

Predicting Poststroke Pneumonia in Patients With Anterior Large Vessel Occlusion: A Prospective, Population-Based Stroke Registry Analysis

Objective

To assess predictive factors for poststroke pneumonia (PSP) in patients with acute ischemic stroke (AIS) due to large vessel occlusion (LVO) of the anterior circulation, with special regard to the impact of intravenous thrombolysis (IVT) and endovascular treatment (EVT) on the risk of PSP. As a secondary goal, the validity of the A²DS², PNEUMONIA, and ISAN scores in LVO will be determined.

Methods

Analysis was based on consecutive data for the years 2017 to 2019 from the prospective inpatient stroke registry covering the entire federal state of Hesse, Germany, using the Kruskal-Wallis test and binary logistic regression.

Results

Data from 4,281 patients with LVO were included in the analysis (54.8% female, median age = 78 years, range = 18–102), of whom 66.4% (n = 2,843) received recanalization therapy (RCT). In total, 19.4% (n = 832) of all LVO patients developed PSP. Development of PSP was associated with an increase in overall in-hospital mortality of 32.1% compared with LVO patients without PSP (16.4%; p < 0.001). Incidence of PSP was increased in 2132 patients with either EVT (n = 928; 25.9% PSP incidence) or combined EVT plus IVT (n = 1,204; 24.1%), compared with 2,149 patients with IVT alone (n = 711; 15.2%) or conservative treatment only (n = 1,438; 13.5%; p < 0.001). Multivariate analysis identified EVT (OR 1.5) and combined EVT plus IVT (OR 1.5) as significant independent risk factors for PSP. Furthermore, male sex (OR 1.9), age ≥ 65 years (OR 1.7), dysphagia (OR 3.2) as well as impaired consciousness at arrival (OR 1.7) and the comorbidities diabetes (OR 1.4) and atrial fibrillation (OR 1.3) were significantly associated risk factors (each p < 0.001). Minor stroke (NIHSS ≤ 4) was associated with a significant lower risk of PSP (OR 0.5). Performance of risk stratification scores varied between A²DS² (96.1% sensitivity, 20.7% specificity), PNEUMONIA (78.2% sensitivity and 45.1% specificity) and ISAN score (98.0% sensitivity, 20.0% specificity).

Conclusion

Nearly one in five stroke patients with LVO develops PSP during acute care. This risk of PSP is further increased if an EVT is performed. Other predictive factors are consistent with those previously described for all AIS patients. Available risk stratification scores proved to be sensitive tools in LVO patients but lack specificity.

Clinical protocol of the ischemic stroke patients treatment

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

Isolation and identification of leukocyte populations in intracranial blood collected during mechanical thrombectomy

Using standard techniques during mechanical thrombectomy, the Blood and Clot Thrombectomy Registry and Collaboration (BACTRAC) protocol (NCT03153683) isolates intracranial arterial blood distal to the thrombus and proximal systemic blood in the carotid artery. We augmented the current protocol to study leukocyte subpopulations both distal and proximal to the thrombus during human stroke (n = 16 patients), and from patients with cerebrovascular disease (CVD) undergoing angiography for unrelated conditions (e.g. carotid artery stenosis; n = 12 patients). We isolated leukocytes for flow cytometry from small volume (<1 mL) intracranial blood and systemic blood (5-10 mL) to identify adaptive and innate leukocyte populations, in addition to platelets and endothelial cells (ECs). Intracranial blood exhibited significant increases in T cell representation and decreases in myeloid/macrophage representation compared to within-patient carotid artery samples. CD4⁺ T cells and classical dendritic cells were significantly lower than CVD controls and correlated to within-patient edema volume and last known normal. This novel protocol successfully isolates leukocytes from small volume intracranial blood samples of stroke patients at time of mechanical thrombectomy and can be used to confirm preclinical results, as well as identify novel targets for immunotherapies.

Workflow Intervals and Outcomes of Endovascular Treatment for Acute Large-Vessel Occlusion During On-Vs. Off-hours in China: The ANGEL-ACT Registry

Background: There may be a delay in or a poor outcome of endovascular treatment (EVT) among acute ischemic stroke (AIS) patients with large-vessel occlusion (LVO) during off-hours. By using a prospective, nationwide registry, we compared the workflow intervals and radiological/clinical outcomes between patients with acute LVO treated with EVT presenting during off- and on-hours.

Methods: We analyzed prospectively collected Endovascular Treatment Key Technique and Emergency Work Flow Improvement of Acute Ischemic Stroke (ANGEL-ACT) data. Patients presenting during off-hours were defined as those presenting to the emergency department from Monday to Friday between 17:30 and 08:00, on weekends (from 17:30 on Friday to 08:00 on Monday), and on national holidays. We used logistic regression models with adjustment for potential confounders to determine independent associations between the time of presentation and outcomes.

Results: Among 1,788 patients, 1,079 (60.3%) presented during off-hours. The median onset-to-door time and onset-to-reperfusion time were significantly longer during off-hours than during on-hours (165 vs. 125 min, P = 0.002 and 410 vs. 392 min, P = 0.027). The rates of successful reperfusion and symptomatic intracranial hemorrhage were similar in both groups. The adjusted odds ratio (OR) for the 90-day modified Rankin Scale score was 0.892 [95% confidence interval (CI), 0.748–1.064]. The adjusted OR for the occurrence of functional independence was 0.892 (95% CI, 0.724–1.098), and the adjusted OR for mortality was 1.214 (95% CI, 0.919–1.603).

Conclusions: Off-hours presentation in the nationwide real-world registry was associated with a delay in the visit and reperfusion time of EVT in patients with AIS. However, this delay was not associated with worse functional outcomes or higher mortality rates.

Clinical Trial Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03370939.

Developing new quantitative CT image markers to predict prognosis of acute ischemic stroke patients

BACKGROUND

Endovascular mechanical thrombectomy (EMT) is an effective method to treat acute ischemic stroke (AIS) patients due to large vessel occlusion (LVO). However, stratifying AIS patients who can and cannot benefit from EMT remains a clinical challenge.

OBJECTIVE

To develop a new quantitative image marker computed from pre-intervention computed tomography perfusion (CTP) images and evaluate its feasibility to predict clinical outcome among AIS patients undergoing EMT after diagnosis of LVO.

METHODS

A retrospective dataset of 31 AIS patients with pre-intervention CTP images is assembled. A computer-aided detection (CAD) scheme is developed to pre-process CTP images of different scanning series for each study case, perform image segmentation, quantify contrast-enhanced blood volumes in bilateral cerebral hemispheres, and compute features related to asymmetrical cerebral blood flow patterns based on the cumulative cerebral blood flow curves of two hemispheres. Next, image markers based on a single optimal feature and machine learning (ML) models fused with multi-features are developed and tested to classify AIS cases into two classes of good and poor prognosis based on the Modified Rankin Scale. Performance of image markers is evaluated using the area under the ROC curve (AUC) and accuracy computed from the confusion matrix.

RESULTS

The ML model using the neuroimaging features computed from the slopes of the subtracted cumulative blood flow curves between two cerebral hemispheres yields classification performance of AUC = 0.878±0.077 with an overall accuracy of 90.3%.

CONCLUSIONS

This study demonstrates feasibility of developing a new quantitative imaging method and marker to predict AIS patients' prognosis in the hyperacute stage, which can help clinicians optimally treat and manage AIS patients.

Platelet distribution width: A significant predictor of poor outcome after mechanical thrombectomy

OBJECTIVES

Elevated platelet distribution width (PDW) is a recognized marker of platelet activity. Herein, we investigated the association between admission PDW values and clinical outcome at 3 months in acute ischemic stroke (AIS) patients undergoing mechanical thrombectomy (MT).

MATERIALS AND METHODS

We retrospectively collected consecutive patients diagnosed with AIS following MT from two stroke centers. PDW was measured on admission. Subjects were divided into two groups according to the clinical outcome using the modified Rankin Scale at 3 months. Multiple regression analyses and receiver operating characteristic (ROC) curves were performed to determine the associations between admission PDW values, clinical parameters, and functional outcome.

RESULTS

A total of 162 subjects were enrolled. Patients in the poor outcome group had a significantly higher percentage of PDW >16.0 fL compared with the good outcome group (57.3% vs. 26.9%, P < 0.001). After adjusting for a range of confounding factors, multiple regression analysis showed that PDW >16.0 fL was an independent predictor of poor outcome at 3 months (odds ratio 4.572, 95% confidence interval 1.896-11.026, P = 0.001). ROC curve analysis revealed that PDW >16.0 fL predicted poor outcome with 57.3% sensitivity and 73.1% specificity (the area under the ROC curve 0.637, 95% confidence interval 0.558-0.711, P = 0.004).

CONCLUSIONS

Elevated PDW is an independent predictor of poor functional outcome in patients with anterior circulation AIS undergoing MT at 3 months.

Trauma Communications Center Coordinated Severity-Based Stroke Triage: Protocol of a Hybrid Type 1 Effectiveness-Implementation Study

Background: Mechanical thrombectomy (MT) can improve the outcomes of patients with large vessel occlusion (LVO), but a minority of patients with LVO are treated and there are disparities in timely access to MT. In part, this is because in most regions, including Alabama, the emergency medical service (EMS) transports all patients with suspected stroke, regardless of severity, to the nearest stroke center. Consequently, patients with LVO may experience delayed arrival at stroke centers with MT capability and worse outcomes. Alabama's trauma communications center (TCC) coordinates EMS transport of trauma patients by trauma severity and regional hospital capability. Our aims are to develop a severity-based stroke triage (SBST) care model based on Alabama's trauma system, compare the effectiveness of this care pathway to current stroke triage in Alabama for improving broad, equitable, and timely access to MT, and explore stakeholder perceptions of the intervention's feasibility, appropriateness, and acceptability.

Methods: This is a hybrid type 1 effectiveness-implementation study with a multi-phase mixed methods sequential design and an embedded observational stepped wedge cluster trial. We will extend TCC guided stroke severity assessment to all EMS regions in Alabama; conduct stakeholder interviews and focus groups to aid in development of region and hospital specific prehospital and inter-facility stroke triage plans for patients with suspected LVO; implement a phased rollout of TCC Coordinated SBST across Alabama's six EMS regions; and conduct stakeholder surveys and interviews to assess context-specific perceptions of the intervention. The primary outcome is the change in proportion of prehospital stroke system patients with suspected LVO who are treated with MT before and after implementation of TCC Coordinated SBST. Secondary outcomes include change in broad public health impact before and after implementation and stakeholder perceptions of the intervention's feasibility, appropriateness, and acceptability using a mixed methods approach. With 1200 to 1300 total observations over 36 months, we have 80% power to detect a 15% improvement in the primary endpoint.

Discussion: This project, if successful, can demonstrate how the trauma system infrastructure can serve as the basis for a more integrated and effective system of emergency stroke care.

Newly-identified blood biomarkers of neurological damage are correlated with infarct volume in patients with acute ischemic stroke

Our group recently performed a genome-wide informatic analysis that highlighted eight brain-enriched proteins with strong potential to serve as blood biomarkers of neurological injury (GFAP, MBP, β-synuclein, OPALIN, MT-3, SNAP-25, KIF5A, MOBP), including six that have yet to be widely investigated. In this study, our aim was to determine whether the circulating levels of these proteins could be used to approximate the extent of neural tissue damage in ischemic stroke. To address this aim, blood was collected from 43 ischemic stroke patients immediately upon hospital admission. The serum levels of the eight candidate proteins were measured via ELISA, infarct volume was assessed via manual tracing of neuroradiological images, and correlational analysis was performed to examine potential associative relationships. The serum levels of all eight proteins exhibited positive correlations with infarct volume, however the strongest associations were observed in a subset of four proteins known to originate from neurons specifically (MT-3, SNAP-25, KIF5A, β-synuclein). Combining the serum levels of these neuron-originating proteins using principal components analysis produced a single composite value that was more strongly correlated with infarct volume than the levels of any single protein considered in isolation (r = 0.48, p < 0.001). Measures of these proteins could potentially be used to provide a minimally invasive approximation of lesion size when advanced imaging techniques are not available, or when imaging results are inconclusive.

Quantified health and cost effects of faster endovascular treatment for large vessel ischemic stroke patients in the Netherlands

BACKGROUND

The effectiveness of endovascular treatment (EVT) for large vessel occlusion (LVO) stroke severely depends on time to treatment. However, it remains unclear what the value of faster treatment is in the years after index stroke. The aim of this study was to quantify the value of faster EVT in terms of health and healthcare costs for the Dutch LVO stroke population.

METHODS

A Markov model was used to simulate 5-year follow-up functional outcome, measured with the modified Rankin Scale (mRS), of 69-year-old LVO patients. Post-treatment mRS was extracted from the MR CLEAN Registry (n=2892): costs per unit of time and Quality-Adjusted Life Years (QALYs) per mRS sub-score were retrieved from follow-up data of the MR CLEAN trial (n=500). Net Monetary Benefit (NMB) at a willingness to pay of €80 000 per QALY was reported as primary outcome, and secondary outcome measures were days of disability-free life gained and costs.

RESULTS

EVT administered 1 min faster resulted in a median NMB of €309 (IQR: 226;389), 1.3 days of additional disability-free life (IQR: 1.0;1.6), while cumulative costs remained largely unchanged (median: -€15, IQR: -65;33) over a 5-year follow-up period. As costs over the follow-up period remained stable while QALYs decreased with longer time to treatment, which this results in a near-linear decrease of NMB. Since patients with faster EVT lived longer, they incurred more healthcare costs.

CONCLUSION

One-minute faster EVT increases QALYs while cumulative costs remain largely unaffected. Therefore, faster EVT provides better value of care at no extra healthcare costs.

Utilization of CT angiography of the head and neck in the era of endovascular therapy for acute ischemic stroke: a retrospective study

PURPOSE

To describe the impact of a new institutional Code Stroke protocol on ordering volume of head and neck CT angiographies (CTA), and to determine the number and proportion of these studies that resulted in an endovascular or surgical intervention.

METHODS

Clinical and administrative data was collected on all head and neck CTAs ordered within the ED at two high-volume community hospitals and an affiliated urgent care centre during the 6-year period between January 1, 2014, and December 31, 2019. Of those patients who underwent CTA, we identified those who were then transferred to a regional stroke centre for consideration of EVT and those who underwent carotid endarterectomy or stenting within 14 days.

RESULTS

A total of 4719 CTAs were ordered during the 6-year period. There was nearly a tenfold rise in the yearly number of CTAs ordered per 10,000 ED visits, from 5.3 (in 2014) to 53.1 (in 2019). A total of 164 patients who underwent CTAs (3.5%) were ultimately transferred to a regional tertiary care centre, of whom 43 (0.9%) were transferred to a regional stroke centre for consideration of EVT. A total of 61 (1.3%) patients underwent a carotid intervention within 14 days.

CONCLUSION

Little is known of the impacts on healthcare resources that have resulted from the system-wide changes made necessary by the widespread adoption of EVT. Our study shows that at our site, these system changes have resulted in large increases in CTA utilization with very small numbers of patients ultimately undergoing EVT or carotid intervention.

Global Epidemiology of Stroke and Access to Acute Ischemic Stroke Interventions

PURPOSE OF THE REVIEW

To provide an up-to-date review of the incidence of stroke and large vessel occlusion (LVO) around the globe, as well as the eligibility and access to IV thrombolysis (IVT) and mechanical thrombectomy (MT) worldwide.

RECENT FINDINGS

Randomized clinical trials have established MT with or without IVT as the usual care for patients with LVO stroke for up to 24 hours from symptom onset. Eligibility for IVT has extended beyond 4.5 hours based on permissible imaging criteria. With these advances in the last 5 years, there has been a notable increase in the population of patients eligible for acute stroke interventions. However, access to acute stroke care and utilization of MT or IVT is lagging in these patients.

SUMMARY

Stroke is the second leading cause of both disability and death worldwide, with the highest burden of the disease shared by low- and middle-income countries. In 2016, there were 13.7 million new incident strokes globally; ≈87% of these were ischemic strokes and by conservative estimation about 10%-20% of these account for LVO. Fewer than 5% of patients with acute ischemic stroke received IVT globally in the eligible therapeutic time window and fewer than 100,000 MTs were performed worldwide in 2016. This highlights the large gap among eligible patients and the low utilization rates of these advances across the globe. Multiple global initiatives are underway to investigate interventions to improve systems of care and bridge this gap.

Imaging as a Selection Tool for Thrombectomy in Acute Ischemic Stroke: Pathophysiologic Considerations

Large vessel occlusion (LVO) stroke represents a stroke subset associated with the highest morbidity and mortality. Multiple prospective randomized trials have shown that thrombectomy, alone or in conjunction with IV thrombolysis, is highly effective in reestablishing cerebral perfusion and improving clinical outcomes. In unselected patients and especially in patients with poor collaterals, the benefit of reperfusion therapy is exquisitely time sensitive; the earlier thrombectomy is started, the lower the likelihood of disability or death. Understanding both the pathophysiologic underpinnings and the modifying factors of this strong time-to-treatment effect demonstrated in numerous randomized clinical trials is important for implementation of intrahospital workflow measures to maximize time efficiency of thrombectomy. Reducing delays in reperfusion therapy initiation has become a priority in acute stroke care, and therefore a thorough understanding of the main systems-based factors responsible for these delays is critical. Because the time spent evaluating the patient in the emergency department, which typically includes neuroimaging studies performed in scanners remote from the angiography suite, represents the main source of delays in thrombectomy initiation, the direct to angiography (DTA) model has emerged as a means to substantially reduce treatment times and is being instituted at an increasing number of thrombectomy centers across the world. The aim of this report is to introduce DTA as an emerging stroke care paradigm for patients with suspicion of LVO stroke, review results from studies evaluating its feasibility and impact on outcomes, describe current barriers to its more widespread adoption, and propose potential solutions to overcoming these barriers.

Stroke Center Designations, Neurointerventionalist Demand, and the Finances of Stroke Thrombectomy in the United States

PURPOSE OF THE REVIEW

This article aims to provide an update on the designation of stroke centers, neurointerventionalist demand, and cost-effectiveness of stroke thrombectomy in the United States.

RECENT FINDINGS

There are now more than 1,660 stroke centers certified by national accrediting bodies in the United States, 306 of which are designated as thrombectomy-capable or comprehensive stroke centers. Considering the amount of nationally certified centers and the number of patients with acute stroke eligible for thrombectomy, each center would be responsible for 64 to 104 thrombectomies per year. As a result, there is a growing demand placed on neurointerventionalists, who have the ability to alter the trajectory of large vessel occlusive strokes. Numbers needed to achieve functional independence after stroke thrombectomy at 90 days range from 3.2 to 7.4 patients in the early time window and 2.8 to 3.6 patients in the extended time window in appropriately selected candidates. With the low number needed to treat, in a variety of valued-based calculations and cost-effectiveness analyses, stroke thrombectomy has proved to be both clinically effective and cost-effective.

SUMMARY

Advancements in the early recognition and treatment of stroke have been paralleled by a remodeling of health care systems to ensure best practices in a timely manner. Stroke center-accrediting bodies provide oversight to safeguard these standards. As successful trial data from high volume centers transform into real-world experience, we must continue to re-evaluate cost-effectiveness, strike a balance between sufficient case volumes to maintain clinical excellence vs the burden and burnout associated with call responsibilities, and improve access to care for all.

Evaluation of Modified Calcium Removal Algorithm in dual energy CT of Internal Carotid Artery

PURPOSE

To evaluate the performance of a dual-energy (DE) calcium removal software based on a modified three-material decomposition algorithm in assessing the stenosis of the internal carotid artery (ICA) in comparison with mixed images using digital subtraction angiography (DSA) as the reference standard.

METHODS

Forty-six patients (38 men; 67±8 years old), including 154 calcified ICA segments C1-C2 (59), C3-C5 (63), C6 (24), and C7 (8), were recruited in this retrospective study. Mixed images and virtual non-calcium (VNCa) images using the modified dual-energy computed tomography (DECT) algorithm were reconstructed. The differences between VNCa and DSA images vs. mixed and DSA images of degree of stenosis were compared. The intraclass correlation coefficient (ICC) was used for assessing the agreement between VNCa, mixed images, and DSA.

RESULTS

The degree of stenosis differed significantly between mixed and DSA images in the C3-C5 (30%±17.9% vs. 23.0%±16.9%, p = 0.026) and C6 (38.3%±15.4% vs. 28.5%±13.3%, p = 0.023) segments. The stenosis of VNCa images showed no significant difference with DSA images in all segments (all p > 0.05). The ICCs between VNCa and DSA images (0.86-0.97) were higher than those between the mixed and DSA images (0.68-0.96) in all segments.

CONCLUSION

The performance of a modified three-material decomposition DECT algorithm for calcium removal in ICA stenosis evaluation, particularly for the C3-C5 and C6 ICA segments, was promising.

Neuroimaging Findings in Patients with COVID-19: A Systematic Review and Meta-Analysis

OBJECTIVE

Central nervous system involvement in coronavirus disease 2019 (COVID-19) has been increasingly reported. We performed a systematic review and meta-analysis to evaluate the incidence of radiologically demonstrated neurologic complications and detailed neuroimaging findings associated with COVID-19.

MATERIALS AND METHODS

A systematic literature search of MEDLINE/PubMed and EMBASE databases was performed up to September 17, 2020, and studies evaluating neuroimaging findings of COVID-19 using brain CT or MRI were included. Several cohort-based outcomes, including the proportion of patients with abnormal neuroimaging findings related to COVID-19 were evaluated. The proportion of patients showing specific neuroimaging findings was also assessed. Subgroup analyses were also conducted focusing on critically ill COVID-19 patients and results from studies that used MRI as the only imaging modality.

RESULTS

A total of 1394 COVID-19 patients who underwent neuroimaging from 17 studies were included; among them, 3.4% of the patients demonstrated COVID-19-related neuroimaging findings. Olfactory bulb abnormalities were the most commonly observed (23.1%). The predominant cerebral neuroimaging finding was white matter abnormality (17.6%), followed by acute/subacute ischemic infarction (16.0%), and encephalopathy (13.0%). Significantly more critically ill patients had COVID-19-related neuroimaging findings than other patients (9.1% vs. 1.6%; p = 0.029). The type of imaging modality used did not significantly affect the proportion of COVID-19-related neuroimaging findings.

CONCLUSION

Abnormal neuroimaging findings were occasionally observed in COVID-19 patients. Olfactory bulb abnormalities were the most commonly observed finding. Critically ill patients showed abnormal neuroimaging findings more frequently than the other patient groups. White matter abnormalities, ischemic infarctions, and encephalopathies were the common cerebral neuroimaging findings.

Automated Large Artery Occlusion Detection in Stroke: A Single-Center Validation Study of an Artificial Intelligence Algorithm

INTRODUCTION

Expediting notification of lesions in acute ischemic stroke (AIS) is critical. Limited availability of experts to assess such lesions and delays in large vessel occlusion (LVO) recognition can negatively affect outcomes. Artificial intelligence (AI) may aid LVO recognition and treatment. This study aims to evaluate the performance of an AI-based algorithm for LVO detection in AIS.

METHODS

Retrospective analysis of a database of AIS patients admitted in a single center between 2014 and 2019. Vascular neurologists graded computed tomography angiographies (CTAs) for presence and site of LVO. Studies were analyzed by the Viz-LVO Algorithm® version 1.4 - neural network programmed to detect occlusions from the internal carotid artery terminus (ICA-T) to the Sylvian fissure. Comparisons between human versus AI-based readings were done by test characteristic analysis and Cohen's kappa. Primary analysis included ICA-T and/or middle cerebral artery (MCA)-M1 LVOs versus non-LVOs/more distal occlusions. Secondary analysis included MCA-M2 occlusions.

RESULTS

610 CTAs were analyzed. The AI algorithm rejected 2.5% of the CTAs due to poor quality, which were excluded from the analysis. Viz-LVO identified ICA-T and MCA-M1 LVOs with a sensitivity of 87.6%, specificity of 88.5%, and accuracy of 87.9% (AUC 0.88, 95% CI: 0.85-0.92, p < 0.001). Cohen's kappa was 0.74. In the secondary analysis, the algorithm yielded a sensitivity of 80.3%, specificity of 88.5%, and accuracy of 82.7%. The mean run time of the algorithm was 2.78 ± 0.5 min.

CONCLUSION

Automated AI reading allows for fast and accurate identification of LVO strokes with timely notification to emergency teams, enabling quick decision-making for reperfusion therapies or transfer to specialized centers if needed.

Similar admission NIHSS may represent larger tissue-at-risk in patients with right-sided versus left-sided large vessel occlusion

BACKGROUND

We investigated the effects of the side of large vessel occlusion (LVO) on post-thrombectomy infarct volume and clinical outcome with regard to admission National Institutes of Health Stroke Scale (NIHSS) score.

METHODS

We retrospectively identified patients with anterior LVO who received endovascular thrombectomy and follow-up MRI. Applying voxel-wise general linear models and multivariate analysis, we assessed the effects of occlusion side, admission NIHSS, and post-thrombectomy reperfusion (modified Thrombolysis in Cerebral Infarction, mTICI) on final infarct distribution and volume as well as discharge modified Rankin Scale (mRS) score.

RESULTS

We included 469 patients, 254 with left-sided and 215 with right-sided LVO. Admission NIHSS was higher in those with left-sided LVO (median (IQR) 16 (10-22)) than in those with right-sided LVO (14 (8-16), p>0.001). In voxel-wise analysis, worse post-thrombectomy reperfusion, lower admission NIHSS score, and poor discharge outcome were associated with right-hemispheric infarct lesions. In multivariate analysis, right-sided LVO was an independent predictor of larger final infarct volume (p=0.003). There was a significant three-way interaction between admission stroke severity (based on NIHSS), LVO side, and mTICI with regard to final infarct volume (p=0.041). Specifically, in patients with moderate stroke (NIHSS 6-15), incomplete reperfusion (mTICI 0-2b) was associated with larger final infarct volume (p<0.001) and worse discharge outcome (p=0.02) in right-sided compared with left-sided LVO.

CONCLUSIONS

When adjusted for admission NIHSS, worse post-thrombectomy reperfusion is associated with larger infarct volume and worse discharge outcome in right-sided versus left-sided LVO. This may represent larger tissue-at-risk in patients with right-sided LVO when applying admission NIHSS as a clinical biomarker for penumbra.

Influence of Platelet Count on Procedure-Related Outcomes After Mechanical Thrombectomy for Large Vessel Occlusion: A Systematic Review and Meta-Analysis

OBJECTIVE

To compare outcomes between patients who underwent mechanical thrombectomy for large vessel occlusion based on platelet count: low versus normal.

METHODS

Three studies were included with a pooled cohort of 1125 patients. Data points were collected and pooled by meta-analysis of proportions via a logit transformation to provide a summary statistic. Both fixed-effect and random-effects models were recruited for the analysis. In this meta-analysis, risk of developing symptomatic intracranial hemorrhage, unfavorable clinical outcomes (modified Rankin Scale score >3), and mortality of patients with low platelet counts were compared with patients with normal platelet counts according to the criteria for inclusion used by each study.

RESULTS

Of patients, 50 (4.7%) had low platelet count, and 1075 (95.3%) had normal platelet count. Patients in the low platelet count group had a substantially higher risk of mortality (risk ratio 1.93, 95% confidence interval 1.43-2.60, P < 0.0001, I² = 0%), but no differences in clinical outcomes (risk ratio 0.66, 95% confidence interval 0.40-1.11, P = 0.12, I² = 0%) or symptomatic intracranial hemorrhage (risk ratio 2.03, 95% confidence interval 0.87-4.70, P = 0.10, I² = 15%) were noted.

CONCLUSIONS

Patients with low platelet counts had increased mortality compared with patients with normal platelet counts following mechanical thrombectomy for large vessel occlusion.

Prevalence and correlates of carotid artery stenosis in a cohort of Sri Lankan ischaemic stroke patients

Background

Large artery atherosclerotic disease is an important cause of stroke, accounting for 15–46% of ischaemic strokes in population-based studies. Therefore, current guidelines from west recommend urgent carotid imaging in all ischaemic strokes or transient ischaemic attacks and referral for carotid endarterectomy. However, the clinical features and epidemiology of stroke in Asians are different from those in Caucasians and therefore the applicability of these recommendations to Asians is controversial. Data on the prevalence of carotid artery stenosis (CAS) among South Asian stroke patients is limited. Therefore, we sought to determine the prevalence and associated factors of significant CAS in a cohort of Sri Lankan patients with ischaemic stroke.

Methods

We prospectively studied all ischaemic stroke patients who underwent carotid doppler ultrasonography admitted to the stroke unit of a Sri Lankan tertiary care hospital over 5 years. We defined carotid stenosis as low (< 50%), moderate (50–69%) or severe (70–99%) or total-occlusion (100%) by North American Symptomatic Trial Collaborators (NASCET) criteria. We identified the factors associated with CAS ≥ 50% and ≥ 70% by stepwise multiple logistic regression analysis.

Results

A total of 550 ischaemic stroke patients (326 (59.3%) male, mean age was 58.9 ± 10.2 years) had carotid doppler ultrasonography. Of them, 528 (96.0%) had low-grade, 12 (2.2%) moderate and 7 (1.3%) severe stenosis and 3 (0.5%) had total occlusion. On multivariate logistic regression, age was associated with CAS ≥ 50% (OR 1.12, p = 0.001) and CAS ≥ 70% (OR 1.14, p = 0.016), but none of the other vascular risk factors studied (sex, hypertension, diabetes mellitus, smoking, past history of TIA, stroke or ischemic heart disease) showed significant associations.

Conclusions

Carotid stenosis is a minor cause of ischemic stroke in Sri Lankans compared to western populations with only 4.0% having CAS ≥ 50 and 3.5% eligible for carotid endarterectomy. Our findings have implications for the management of acute strokes in Sri Lanka.

Comparison of convolutional neural networks for detecting large vessel occlusion on computed tomography angiography

PURPOSE

Artificial intelligence diagnosis and triage of large vessel occlusion may quicken clinical response for a subset of time-sensitive acute ischemic stroke patients, improving outcomes. Differences in architectural elements within data-driven convolutional neural network (CNN) models impact performance. Foreknowledge of effective model architectural elements for domain-specific problems can narrow the search for candidate models and inform strategic model design and adaptation to optimize performance on available data. Here, we study CNN architectures with a range of learnable parameters and which span the inclusion of architectural elements, such as parallel processing branches and residual connections with varying methods of recombining residual information.

METHODS

We compare five CNNs: ResNet-50, DenseNet-121, EfficientNet-B0, PhiNet, and an Inception module-based network, on a computed tomography angiography large vessel occlusion detection task. The models were trained and preliminarily evaluated with 10-fold cross-validation on preprocessed scans (n = 240). An ablation study was performed on PhiNet due to superior cross-validated test performance across accuracy, precision, recall, specificity, and F1 score. The final evaluation of all models was performed on a withheld external validation set (n = 60) and these predictions were subsequently calibrated with sigmoid curves.

RESULTS

Uncalibrated results on the withheld external validation set show that DenseNet-121 had the best average performance on accuracy, precision, recall, specificity, and F1 score. After calibration DenseNet-121 maintained superior performance on all metrics except recall.

CONCLUSIONS

The number of learnable parameters in our five models and best-ablated PhiNet directly related to cross-validated test performance-the smaller the model the better. However, this pattern did not hold when looking at generalization on the withheld external validation set. DenseNet-121 generalized the best; we posit this was due to its heavy use of residual connections utilizing concatenation, which causes feature maps from earlier layers to be used deeper in the network, while aiding in gradient flow and regularization.

Trevo 6 × 25mm vs. 4 × 30mm in Mechanical Thrombectomy of M1 LVO

Objectives: Our primary objective was to determine the successful rate of recanalization of M1 large vessel occlusion using either the Trevo 4 × 30 mm or 6 × 25 mm stent during mechanical thrombectomy. Our secondary objectives were to determine differences between the use of these two stent retrievers regarding first-pass effect, periprocedural complications, and mortality in the first 90 days. Methods: This is a retrospective cohort study. Data regarding the stent used, recanalization, number of passes, periprocedural complications, and mortality were determined via our mechanical thrombectomy database along with chart review. Conclusion: When comparing Trevo 4 × 30 mm to 6 × 25 mm stent retrievers used in mechanical thrombectomy for middle cerebral artery large-vessel occlusion causing stroke, there is no statistically significant difference in successful recanalization rates, first-pass effect, perioperative complications, or mortality at 90 days. Studies like this will hopefully lead to further prospective, randomized controlled trials that will help show experts in the field an additional way to perform this procedure effectively and safely.

The significance of the morphology-voltage-P-wave duration (MVP) ECG score for prediction of in-hospital and long-term atrial fibrillation in ischemic stroke

BACKGROUND

Atrial fibrillation (AF) is the most common preventable cause of stroke. Diagnosis of new AF is frequent after acute ischemic stroke (AIS). We aimed to evaluate the predictive value of the recently developed morphology-voltage-P-wave duration (MVP) ECG risk score for in-hospital and long-term AF diagnosis following AIS.

MATERIAL AND METHODS

In this observational investigation, we evaluated the ability of the MVP ECG risk score to predict AF in 266 consecutive patients with AIS. The study population was divided into three groups according to their calculated MVP ECG risk score on admission electrocardiography. The groups were compared in terms of their predictive value for in-hospital and long-term AF diagnosis.

RESULTS

After adjustment for confounding baseline variables, MVP ECG risk score 5-6 group had 13.2 times higher rates of in-hospital AF compared to MVP ECG risk score 0-2 group, which was used as the reference group. For long-term follow-up, MVP ECG risk score 5-6 group had 5.2 times higher rates of long-term AF compared to MVP ECG risk score 0-2 group. A ROC analysis showed that the optimal cut-off value of the MVP ECG risk score to predict in-hospital AF was 4 with 78% sensitivity and 76% specificity (AUC: 0.80; 95% CI: 0.64-0.96; p < 0.001), the optimal cut-off value of the MVP ECG risk score to predict long-term AF was 3 with 85% sensitivity and 59% specificity (AUC: 0.81; 95% CI: 0.76-0.86; p < 0.001).

CONCLUSION

The MVP ECG risk score, which can be easily calculated from a surface ECG, can be used to guide who needs stricter monitoring for the diagnosis of long-term AF in patients with AIS.

Left Atrial Enlargement on Non-Gated CT Is Associated with Large Vessel Occlusion in Acute Ischaemic Stroke

Background

Recent reports have suggested that atrial fibrillation (AF) is more prevalent in the large vessel occlusion (LVO) subgroup of acute ischaemic stroke patients. Given the association between left atrial enlargement (LAE) and AF, we sought to evaluate the feasibility of assessing LAE on non-gated CT and its association with LVO in the hyperacute stroke setting.

Methods

We analysed our prospectively collected database that included all stroke patients referred for consideration of endovascular treatment between April 14, 2020, and May 21, 2020. During this period, a CT chest was included in our regional stroke protocol to aid triage of patients suspected for COVID-19 from which cardiac measurements were obtained. Patients were dichotomized into LVO and no-LVO groups, and LA measurements were trichotomized into normal, borderline, and enlarged. Univariate analyses were performed between groups.

Results

Of the included 38 patients, 21 were categorized as LVO and 17 as no LVO. There was a statistically significant association between LAE and LVO (p = 0.028). No significant difference was demonstrated between groups for the baseline AF and other clinical characteristics, except for baseline NIHSS (p = 0.0005). There was excellent inter- and intra-rater reliability (ICC = 0.969) for LA measurements.

Conclusion

Our study provides preliminary data to suggest LAE is more prevalent in the LVO stroke subgroup at presentation and can be reliably assessed on non-gated CT in the hyperacute setting. These findings have potential implications for stratifying secondary management and may prompt a more rigorous pursuit of occult AF or other cardiac causes of stroke.

Blood Pressure Management After Endovascular Thrombectomy

Endovascular thrombectomy (EVT) has changed the landscape of acute stroke therapy and has become the standard of care for selected patients presenting with anterior circulation large-vessel occlusion (LVO) stroke. Despite successful reperfusion, many patients with LVO stroke do not regain functional independence. Particularly, patients presenting with extremes of blood pressure (BP) or hemodynamic variability are found to have a worse clinical recovery, suggesting blood pressure optimization as a potential neuroprotective strategy. Current guidelines acknowledge the lack of randomized trials to evaluate the optimal hemodynamic management during the immediate post-stroke period. Following reperfusion, lower blood pressure targets may be warranted to prevent reperfusion injury and promote penumbral recovery, but adequate BP targets adjusted to individual patient factors such as degree of reperfusion, infarct size, and overall hemodynamic status remain undefined. This narrative review outlines the physiological mechanisms of BP control after EVT and summarizes key observational studies and clinical trials evaluating post-EVT BP targets. It also discusses novel treatment strategies and areas of future research that could aid in the determination of the optimal post-EVT blood pressure.

Outcomes of Endovascular Therapy in Patients With Prestroke Mobility Impairment

[Figure: see text].

Performance of Automated Attenuation Measurements at Identifying Large Vessel Occlusion Stroke on CT Angiography

PURPOSE

Computed tomography angiography (CTA) is routinely used to detect large-vessel occlusion (LVO) in patients with suspected acute ischemic stroke; however, visual analysis is time consuming and prone to error. To evaluate solutions to support imaging triage, we tested performance of automated analysis of CTA source images (CTASI) at identifying patients with LVO.

METHODS

Stroke patients with LVO were selected from a prospectively acquired cohort. A control group was selected from consecutive patients with clinically suspected stroke without signs of ischemia on CT perfusion (CTP) or infarct on follow-up. Software-based automated segmentation and Hounsfield unit (HU) measurements were performed on CTASI for all regions of the Alberta Stroke Program Early CT score (ASPECTS). We derived different parameters from raw measurements and analyzed their performance to identify patients with LVO using receiver operating characteristic curve analysis.

RESULTS

The retrospective analysis included 145 patients, 79 patients with LVO stroke and 66 patients without stroke. The parameters hemispheric asymmetry ratio (AR), ratio between highest and lowest regional AR and M2-territory AR produced area under the curve (AUC) values from 0.95-0.97 (all p < 0.001) for detecting presence of LVO in the total population. Resulting sensitivity (sens)/specificity (spec) defined by the Youden index were 0.87/0.97-0.99. Maximum sens/spec defined by the specificity threshold ≥0.70 were 0.91-0.96/0.77-0.83. Performance in a small number of patients with isolated M2 occlusion was lower (AUC: 0.72-0.85).

CONCLUSION

Automated attenuation measurements on CTASI identify proximal LVO stroke patients with high sensitivity and specificity. This technique can aid in accurate and timely patient selection for thrombectomy, especially in primary stroke centers without CTP capacity.

Optimizing Emergency Stroke Transport Strategies Using Physiological Models

Supplemental Digital Content is available in the text.

The criteria for choosing between drip and ship and mothership transport strategies in emergency stroke care is widely debated. Although existing data-driven probability models can inform transport decision-making at an epidemiological level, we propose a novel mathematical, physiologically derived framework that provides insight into how patient characteristics underlying infarct core growth influence these decisions.

Incidence, Characteristics and Outcomes of Large Vessel Stroke in COVID-19 Cohort: An International Multicenter Study

BACKGROUND

While there are reports of acute ischemic stroke (AIS) in coronavirus disease 2019 (COVID-19) patients, the overall incidence of AIS and clinical characteristics of large vessel occlusion (LVO) remain unclear.

OBJECTIVE

To attempt to establish incidence of AIS in COVID-19 patients in an international cohort.

METHODS

A cross-sectional retrospective, multicenter study of consecutive patients admitted with AIS and COVID-19 was undertaken from March 1 to May 1, 2020 at 12 stroke centers from 4 countries. Out of those 12 centers, 9 centers admitted all types of strokes and data from those were used to calculate the incidence rate of AIS. Three centers exclusively transferred LVO stroke (LVOs) patients and were excluded only for the purposes of calculating the incidence of AIS. Detailed data were collected on consecutive LVOs in hospitalized patients who underwent mechanical thrombectomy (MT) across all 12 centers.

RESULTS

Out of 6698 COVID-19 patients admitted to 9 stroke centers, the incidence of stroke was found to be 1.3% (interquartile range [IQR] 0.75%-1.7%). The median age of LVOs patients was 51 yr (IQR 50-75 yr), and in the US centers, African Americans comprised 28% of patients. Out of 66 LVOs, 10 patients (16%) were less than 50 yr of age. Among the LVOs eligible for MT, the average time from symptom onset to presentation was 558 min (IQR 82-695 min). A total of 21 (50%) patients were either discharged to home or discharged to acute rehabilitation facilities.

CONCLUSION

LVO was predominant in patients with AIS and COVID-19 across 2 continents, occurring at a significantly younger age and affecting African Americans disproportionately in the USA.

A Novel Combination of Blood Biomarkers and Clinical Stroke Scales Facilitates Detection of Large Vessel Occlusion Ischemic Strokes

Acute ischemic stroke caused by large vessel occlusions (LVOs) is a major contributor to stroke deaths and disabilities; however, identification for emergency treatment is challenging. We recruited two separate cohorts of suspected stroke patients and screened a panel of blood-derived protein biomarkers for LVO detection. Diagnostic performance was estimated by using blood biomarkers in combination with NIHSS-derived stroke severity scales. Multivariable analysis demonstrated that D-dimer (OR 16, 95% CI 5–60; p-value < 0.001) and GFAP (OR 0.002, 95% CI 0–0.68; p-value < 0.05) comprised the optimal panel for LVO detection. Combinations of D-dimer and GFAP with a number of stroke severity scales increased the number of true positives, while reducing false positives due to hemorrhage, as compared to stroke scales alone (p-value < 0.001). A combination of the biomarkers with FAST-ED resulted in the highest accuracy at 95% (95% CI: 87–99%), with sensitivity of 91% (95% CI: 72–99%), and specificity of 96% (95% CI: 90–99%). Diagnostic accuracy was confirmed in an independent cohort, in which accuracy was again shown to be 95% (95% CI: 87–99%), with a sensitivity of 82% (95% CI: 57–96%), and specificity of 98% (95% CI: 92–100%). Accordingly, the combination of D-dimer and GFAP with stroke scales may provide a simple and highly accurate tool for identifying LVO patients, with a potential impact on time to treatment.

Geographic Access to Stroke Care Services in Rural Communities in Ontario, Canada

BACKGROUND

Optimal stroke care requires access to resources such as neuroimaging, acute revascularization, rehabilitation, and stroke prevention services, which may not be available in rural areas. We aimed to determine geographic access to stroke care for residents of rural communities in the province of Ontario, Canada.

METHODS

We used the Ontario Road Network File database linked with the 2016 Ontario Acute Stroke Care Resource Inventory to estimate the proportion of people in rural communities, defined as those with a population size <10,000, who were within 30, 60, and 240 minutes of travel time by car from stroke care services, including brain imaging, thrombolysis treatment centers, stroke units, stroke prevention clinics, inpatient rehabilitation facilities, and endovascular treatment centers.

RESULTS

Of the 1,496,262 people residing in rural communities, the majority resided within 60 minutes of driving time to a center with computed tomography (85%), thrombolysis (81%), a stroke unit (68%), a stroke prevention clinic (74%), or inpatient rehabilitation (77.0%), but a much lower proportion (32%) were within 60 minutes of driving time to a center capable of providing endovascular thrombectomy (EVT).

CONCLUSIONS

Most rural Ontario residents have appropriate geographic access to stroke services, with the exception of EVT. This information may be useful for jurisdictions seeking to optimize the regional organization of stroke care services.

Correlations Between Physician and Hospital Stroke Thrombectomy Volumes and Outcomes: A Nationwide Analysis

[Figure: see text].

Acute reperfusion therapies for acute ischemic stroke patients with unknown time of symptom onset or in extended time windows: an individualized approach

Recent randomized controlled clinical trials (RCTs) have revolutionized acute ischemic stroke care by extending the use of intravenous thrombolysis and endovascular reperfusion therapies in time windows that have been originally considered futile or even unsafe. Both systemic and endovascular reperfusion therapies have been shown to improve outcome in patients with wake-up strokes or symptom onset beyond 4.5 h for intravenous thrombolysis and beyond 6 h for endovascular treatment; however, they require advanced neuroimaging to select stroke patients safely. Experts have proposed simpler imaging algorithms but high-quality data on safety and efficacy are currently missing. RCTs used diverse imaging and clinical inclusion criteria for patient selection during the dawn of this novel stroke treatment paradigm. After taking into consideration the dismal prognosis of nonrecanalized ischemic stroke patients and the substantial clinical benefit of reperfusion therapies in selected late presenters, we propose rescue reperfusion therapies for acute ischemic stroke patients not fulfilling all clinical and imaging inclusion criteria as an option in a subgroup of patients with clinical and radiological profiles suggesting low risk for complications, notably hemorrhagic transformation as well as local or remote parenchymal hemorrhage. Incorporating new data to treatment algorithms may seem perplexing to stroke physicians, since treatment and imaging capabilities of each stroke center may dictate diverse treatment pathways. This narrative review will summarize current data that will assist clinicians in the selection of those late presenters that will most likely benefit from acute reperfusion therapies. Different treatment algorithms are provided according to available neuroimaging and endovascular treatment capabilities.

Baseline Characteristics of Patients with Symptomatic Carotid Webs: A Matched Case Control Study

BACKGROUND AND PURPOSE

The baseline characteristics of patients with symptomatic carotid web (CaW) are unclear. We investigate demographic and cerebrovascular risk factors in patients with this overlooked stroke etiology.

METHODS

We identified consecutive patients diagnosed with symptomatic CaW at a comprehensive stroke center from July 2014-December 2018. These patients were matched at a 1:4 ratio (based on age and NIHSS scores) to create a control group of acute ischemic stroke (AIS) patients with non-CaW etiologies from the local GetWithTheGuidelines stroke database.

RESULTS

Thirty patients with symptomatic CaW were compared to 120 AIS patients with non-CaW etiologies. Symptomatic CaW patients were more likely to be female (73.3 vs. 44.2%; p = 0.004) and black (86.7 vs. 64.2%; p = 0.02). Symptomatic CaWs patients had a fewer absolute number of modifiable cerebrovascular risk factors (1.7±1.1 vs. 2.5±1.2; p = 0.002), lower rates of hypertension (43.4 vs. 63.3%; p = 0.04), and a more favorable lipid profile with lower average LDL (89.5±30.3 vs. 111.2±43.7 mg/dL; p = 0.01) and higher average HDL (47.9±11.3 vs. 42.2±13.8 mg/dL; p = 0.01) as compared to strokes with non-CaW etiology. Symptomatic CaW patients were more likely to have a large vessel occlusion (80.0 vs. 51.7%; p = 0.005), despite similar e-ASPECTS between the groups (8.1±2.1 vs. 8.3±2.2; p = 0.30). On multivariable analysis, symptomatic CaW was an independent predictor of independence at discharge (OR 3.72; 95%CI 1.27-10.94).

CONCLUSION

A gender and racial predilection of symptomatic CaWs may exist as females and blacks were were found to be more likely affected. Symptomatic CaW patients have a more benign cerebrovascular risk factor profile corroborating the proposed mechanism of local stasis and thromboembolism. Despite presenting more commonly with LVO, symptomatic CaW was associated with good functional outcome, warranting further studies.

Mean Platelet Volume as a Potential Marker of Large Vessel Occlusion and Predictor of Outcome in Acute Ischemic Stroke Patients Treated with Reperfusion Therapy

(1) Background: An early diagnosis of a large vessel occlusion (LVO) is crucial in the management of the acute ischemic stroke (AIS). The laboratory predictors of LVO and a stroke outcome remain unknown. We have hypothesized that high MPV—a surrogate marker of the activated platelet—may be associated with LVO, and it may predict a worse AIS outcome. (2) Methods: This was a retrospective study of 361 patients with AIS who were treated with thrombolysis (tPA, 65.7%) and/or mechanical thrombectomy (MT, 34.3%) in a tertiary Stroke Center between 2011 and 2019. (3) Results: The mean MPV in the cohort was 9.86 ± 1.5 fL (1st–4th quartiles: <8.8, >10.80 fL). Patients in the 4th quartile compared to the 1st had a significantly (p < 0.01) more often incidence of an LVO related stroke (75% vs. 39%) and a severe stroke manifestation with a higher RACE score (5.2 ± 2.8 vs. 3.3 ± 2.4), NIHSS at baseline (mean ± SD, 14 ± 6.5 vs. 10.9 ± 5.2), and NIHSS at discharge (6.9 ± 7 vs. 3.9 ± 3.6). A multivariate analysis revealed that quartiles of MPV (OR 1.4; 95%CI 1.2–1.8) significantly predicted an LVO stroke, also after the adjustment for RACE < 5 (OR 1.4; 95%CI 1.08–1.89), but MPV quartiles did not predict a favorable stroke outcome (mRS ≤ 2) (OR 0.89; 95%CI 0.7–1.13). (4) Conclusion: Our data suggest that MPV is an independent predictor of LVO in patients with an acute ischemic stroke.

Mechanical Thrombectomy Improves Outcome for Large Vessel Occlusion Stroke after Cardiac Surgery

BACKGROUND

Stroke is a feared complication of cardiac surgery. Modern clot-retrieval techniques provide effective treatment for large vessel occlusion (LVO) strokes. The purpose of this study was to 1) report the incidence of LVO stroke after cardiac surgery at a large academic center, and 2) describe outcomes of postoperative LVO strokes.

METHODS

All patients experiencing stroke within 30 days after undergoing cardiac surgery at a single center in 2014-2018 were reviewed. LVOs were identified through review of imaging and medical records, and their characteristics and clinical courses were examined.

RESULTS

Over the study period, 7,112 cardiac surgeries, including endovascular procedures, were performed. Acute ischemic stroke within 30 days after surgery was noted in 163 patients (2.3%). Among those with a stroke, 51/163 (31.3%) had a CTA or MRA, and 15/163 (9.2%) presented with LVO stroke. For all stroke patients, the median time from surgery to stroke was 2 days (interquartile range, IQR, 0-6 days), and for patients with LVO, the median time from surgery to stroke was 4 days (IQR 0-6 days). The overall rate of postoperative LVO was 0.2% (95% CI 0.1-0.4%), though only 6/15 received thrombectomy. LVO patients receiving thrombectomy were significantly more likely to return to independent living compared to those managed medically (n = 4/6, 66.6% for mechanical thrombectomy vs. n = 0/9, 0% for medical management, P = .01). Of the 9 patients who did not get thrombectomy, 6 may currently be candidates for thrombectomy given new expanded treatment windows.

CONCLUSIONS

The rate of LVO after cardiac surgery is low, though substantially elevated above the general population, and the majority do not receive thrombectomy currently. Patients receiving thrombectomy had improved neurologic outcomes compared to patients managed medically. Optimized postoperative care may increase the rate of LVO recognition, and cardiac surgery patients and their caregivers should be aware of this effective therapy.

Predictive Factors of Perioperative Stroke-Related Mortality Following Vascular Surgery: A Retrospective Analysis

OBJECTIVE

Vascular surgical procedures have one of the highest risks of perioperative stroke and stroke-related mortality, yet the independent risk factors contributing to this increased mortality have not been described. Perioperative strokes are thought to result from a combination of embolism and hypoperfusion mechanisms. The purpose of this study is to describe the independent predictors of perioperative stroke-related mortality in the vascular surgical population using the Pennsylvania Health Care Cost Containment Council (PHC4) database which collects cause of death data.

METHODS

This retrospective, case-control study evaluated 4,128 patients aged 18-99 who underwent a vascular, non-carotid surgical procedure and subsequently suffered perioperative mortality. Common surgical comorbidities and risk factors for perioperative stroke, including carotid stenosis and atrial fibrillation, were evaluated in multivariate regression analysis.

RESULTS

Patients with carotid stenosis were 2.6 (aOR, 95% CI 1.4-4.5) times more likely to suffer perioperative mortality from stroke than from other causes. Additionally, in-hospital stroke, history of stroke, admission from a healthcare facility, and cancer were all positive predictive factors, whereas atrial fibrillation, emergency admission, hypertension, and diabetes were associated with decreased risk of perioperative stroke-related mortality.

CONCLUSIONS

Identification of vascular surgical population-specific predictors of stroke-related mortality can help to enhance preoperative risk-stratification tools and guide perioperative management of identified high-risk patients. Increased neurophysiologic monitoring in the perioperative period to prevent delays in diagnosis of perioperative stroke offers a strategy to reduce risk of perioperative stroke-related mortality in vascular surgical patients.

Detection of Large Vessel Occlusion Stroke in the Prehospital Setting: Electroencephalography as a Potential Triage Instrument

A reliable and fast instrument for prehospital detection of large vessel occlusion (LVO) stroke would be a game-changer in stroke care, because it would enable direct transportation of LVO stroke patients to the nearest comprehensive stroke center for endovascular treatment. This strategy would substantially improve treatment times and thus clinical outcomes of patients. Here, we outline our view on the requirements of an effective prehospital LVO detection method, namely: high diagnostic accuracy; fast application and interpretation; user-friendliness; compactness; and low costs. We argue that existing methods for prehospital LVO detection, including clinical scales, mobile stroke units and transcranial Doppler, do not fulfill all criteria, hindering broad implementation of these methods. Instead, electroencephalography may be suitable for prehospital LVO detection since in-hospital studies have shown that quantification of hypoxia-induced changes in the electroencephalography signal have good diagnostic accuracy for LVO stroke. Although performing electroencephalography measurements in the prehospital setting comes with challenges, solutions for fast and simple application of this method are available. Currently, the feasibility and diagnostic accuracy of electroencephalography in the prehospital setting are being investigated in clinical trials.

SARS-CoV-2 and Stroke Characteristics: A Report From the Multinational COVID-19 Stroke Study Group

[Figure: see text].

Validation of a Deep Learning Tool in the Detection of Intracranial Hemorrhage and Large Vessel Occlusion

Purpose: Recently developed machine-learning algorithms have demonstrated strong performance in the detection of intracranial hemorrhage (ICH) and large vessel occlusion (LVO). However, their generalizability is often limited by geographic bias of studies. The aim of this study was to validate a commercially available deep learning-based tool in the detection of both ICH and LVO across multiple hospital sites and vendors throughout the U.S.

Materials and Methods: This was a retrospective and multicenter study using anonymized data from two institutions. Eight hundred fourteen non-contrast CT cases and 378 CT angiography cases were analyzed to evaluate ICH and LVO, respectively. The tool's ability to detect and quantify ICH, LVO, and their various subtypes was assessed among multiple CT vendors and hospitals across the United States. Ground truth was based off imaging interpretations from two board-certified neuroradiologists.

Results: There were 255 positive and 559 negative ICH cases. Accuracy was 95.6%, sensitivity was 91.4%, and specificity was 97.5% for the ICH tool. ICH was further stratified into the following subtypes: intraparenchymal, intraventricular, epidural/subdural, and subarachnoid with true positive rates of 92.9, 100, 94.3, and 89.9%, respectively. ICH true positive rates by volume [small (<5 mL), medium (5–25 mL), and large (>25 mL)] were 71.8, 100, and 100%, respectively. There were 156 positive and 222 negative LVO cases. The LVO tool demonstrated an accuracy of 98.1%, sensitivity of 98.1%, and specificity of 98.2%. A subset of 55 randomly selected cases were also assessed for LVO detection at various sites, including the distal internal carotid artery, middle cerebral artery M1 segment, proximal middle cerebral artery M2 segment, and distal middle cerebral artery M2 segment with an accuracy of 97.0%, sensitivity of 94.3%, and specificity of 97.4%.

Conclusion: Deep learning tools can be effective in the detection of both ICH and LVO across a wide variety of hospital systems. While some limitations were identified, specifically in the detection of small ICH and distal M2 occlusion, this study highlights a deep learning tool that can assist radiologists in the detection of emergent findings in a variety of practice settings.

"Thrombectomy and Back:" A Novel Approach for Treating Patients with Large Vessel Occlusion in the Eastern Province of Saudi Arabia

Background:

Timely access to comprehensive stroke centers for patients suffering from acute ischemic stroke due to large vessel occlusion (LVO) remains a commonly encountered obstacle worldwide, especially in areas with no comprehensive stroke or thrombectomy-capable stroke centers.

Objective:

To present our novel experience with a “thrombectomy-and-back” model implemented in the Eastern Province of Saudi Arabia.

Methods:

King Fahd Hospital of the University (KFHU), a 600-bed hospital located in Al Khobar with an open-access emergency department, was designated as a comprehensive stroke center in the Eastern Province. “Thrombectomy-and-back” was designed such that the neurologist in the referring hospital directly communicates with the attending neurovascular team at KFHU for their anticipation of the case, and subsequently confirms LVO presence through urgent acquisition of a CT and a CT angiogram. Once LVO was confirmed, the patients were timely transferred to KFHU for mechanical thrombectomy. Upon procedure completion, the patients returned to the referring hospital with the same medical and EMS team. The safety of transfer and peri-procedural complications were analyzed.

Results:

From December 2017 to December 2019, 20 thrombectomy-and-back codes were activated, of which 10 were deactivated on negative LVO and 10 remained activated. Of these 10 patients, 2 required admission to our hospital's Neuro-ICU: one was because the middle cerebral artery reoccluded during the procedure and the other was due to hemodynamic instability upon arrival; this first patient passed away 2 months later due to the complications of the malignant left middle cerebral artery stroke.

Conclusions:

The novel Thrombectomy-and-Back model in the Eastern Province of Saudi Arabia has proved to be a safe and efficient approach for patients presenting with LVO to receive timely interventional therapy and minimizing futile transfers.

The emerging association between COVID-19 and acute stroke

Prior to COVID-19, only two human-tropic coronaviruses resulted in epidemics and cerebrovascular disease was rarely reported. Evidence now suggests that 1-6% of hospitalized COVID-19 patients develop stroke. According to some reports, stroke risk is more than sevenfold greater in patients with COVID-19 than influenza. Concerningly, outcomes of COVID-19-related stroke are often worse than in stroke patients without COVID-19 from the same cohorts. In this review, we highlight the emerging association between COVID-19 and stroke and discuss putative pathogenetic mechanisms. Etiology of stroke in COVID-19 patients is likely multifactorial, related to coagulopathy, inflammation, platelet activation, and alterations to the vascular endothelium. Significant work remains to be done to better understand the pathogenesis of COVID-19-related stroke and for designing optimal primary and secondary prevention strategies.

The benefit of intravenous thrombolysis prior to mechanical thrombectomy within the therapeutic window for acute ischemic stroke

The increase in risk for acute ischemic stroke (AIS) with age is well established. If not treated properly and promptly, AIS can result in permanent neurological damage and even death. This literature review assesses the clinical outcomes of AIS patients treated with both intravenous thrombolysis (IVT) prior to mechanical thrombectomy (MT) compared to those treated solely with mechanical thrombectomy. Randomized controlled trials (RCTs) and meta-analyses published from 2015 to 2020 and available on PubMed were selected for review, and their quantitative and qualitative findings were extrapolated and summarized. Post-hoc analyses from ASTER and ETIS trials were reviewed as well as the impact of combined therapy and monotherapy on large vessel occlusions (LVO). Clinical outcomes in all examined trials demonstrated significant successful reperfusion as well as a higher rate of functional independence at 90 days for IVT prior to MT. Concerns of thrombus fragility, safety and cost effectiveness of dual therapy are also addressed. Based on these findings, we recommend the use of IVT as a pretreatment procedure to MT for AIS when eligible for IVT. Recent articles further strengthen this recommendation and provide new insights that IVT prior to MT is especially beneficial for patients presenting with multiple LVOs localized to the anterior intracranial circulation. Additional multi-center RCTs are necessary for further analysis of statistical outcomes demonstrating mixed effects.

Association of Carotid Artery Endothelial Signal Intensity Gradient with Unilateral Large Artery Ischemic Stroke

BACKGROUND

Common carotid artery (CCA) and internal carotid artery (ICA) are aligned linearly, but their hemodynamic role in ischemic stroke has not been studied in depth.

OBJECTIVES

We aimed to investigate whether CCA and ICA endothelial shear stress (ESS) could be associated with the ischemic stroke of large artery atherosclerosis (LAA).

METHODS

We enrolled consecutive patients with unilateral ischemic stroke of LAA and healthy controls aged >60 years in the stroke center of Jeonbuk National University Hospital. All patients and controls were examined with carotid artery time-of-flight magnetic resonance angiography, and their endothelial signal intensity gradients (SIGs) were determined, as a measure of ESS. The effect of right or left unilateral stroke on the association between carotid artery endothelial SIG and ischemic stroke of LAA was assessed.

RESULTS

In total, the results from 132 patients with ischemic stroke of LAA and 121 controls were analyzed. ICA endothelial SIG showed significant and independent associations with the same-sided unilateral ischemic stroke of LAA, even after adjusting for the potential confounders including carotid stenosis, whereas CCA endothelial SIG showed a significant association with the presence of the ischemic stroke of LAA.

CONCLUSION

Although CCA and ICA are located with continuity, the hemodynamics and their roles in large artery ischemic stroke should be considered separately. Further studies are needed to delineate the pathophysiologic roles of ESS in CCA and ICA for large artery ischemic stroke.

Acute Ischemic Stroke in Patients With COVID-19: An Analysis From Get With The Guidelines-Stroke

[Figure: see text].

Early Venous Filling Following Thrombectomy: Association With Hemorrhagic Transformation and Functional Outcome

Background and Purpose: Previous studies have noted the angiographic appearance of early venous filling (EVF) following recanalisation in acute ischemic stroke. However, the prognostic implications of EVF as a novel imaging biomarker remain unclear. We aimed to evaluate the correlation between EVF with (i) the risk of subsequent reperfusion hemorrhage (RPH) and (ii) the association of EVF on both the NIHSS score at 24 h and functional outcome as assessed with the Modified Rankin Scale (mRS) score at 90 days. Methods: We conducted a retrospective cohort study of patients presenting with an acute ischemic stroke due to a proximal large-vessel occlusion of the anterior circulation treated by thrombectomy. Post-reperfusion digital subtraction angiography was reviewed to look for EVF as evidenced by the contrast opacification of any cerebral vein before the late arterial phase. Results: EVF occurred in 22.4% of the 147 cases included. The presence of EVF significantly increased the risk of RPH (p = 0.0048), including the risk of symptomatic hemorrhage (p = 0.0052). The presence of EVF (p = 0.0016) and the absence of RPH (p = 0.0021) were independently associated with a better outcome as defined by the NIHSS difference at 24 h, most significantly in the EVF⁺RPH^- group. No significant relationship was however found between either EVF or RPH and a mRS score ≤ 2 at 90 days. Conclusion: Early venous filling on angiographic imaging is a potential predictor of reperfusion hemorrhage. The absence of subsequent RPH in this sub-group is associated with better outcomes at 24 h post-thrombectomy than in those with RPH.

Stroke Preventability in Large Vessel Occlusion Treated With Mechanical Thrombectomy

Objective: The preventability of strokes treated by mechanical thrombectomy is unknown. The purpose of this study was to analyze stroke preventability for patients treated with mechanical thrombectomy for large vessel occlusion.

Methods: We conducted retrospective analyses of 300 patients (mean ± SE age 69 ± 0.9 years, range 18–97 years; 53% male) treated with mechanical thrombectomy for large vessel occlusion from January 2008 to March 2019. We collected data including demographics, NIH Stroke Scale (NIHSS) at onset, and (beginning in 2015) classified 90-day outcome by modified Rankin Scale (mRS). Patients were evaluated using a Stroke Preventability Score (SPS, 0 to 10 points) based on how well patients had been treated given their hypertension, hyperlipidemia, atrial fibrillation, and prior stroke history. We examined the relationship of SPS with NIHSS at stroke onset and with mRS outcome at 90 days.

Results: SPS was calculated for 272 of the 300 patients, with mean ± SE of 2.1 ± 0.1 (range 0–8); 89 (33%) had no preventability (score 0), 120 (44%) had low preventability (score 1–3), and 63 (23%) had high preventability (score 4 or higher). SPS was significantly correlated with age (r = 0.32, p < 0.0001), while NIHSS (n = 267) was significantly higher (p = 0.03) for patients with high stroke preventability vs. low/no preventability [18.8 ± 0.92 (n = 62) vs. 16.5 ± 0.51 (n = 205)]. Among 118 patients with mRS, outcome was significantly worse (p = 0.04) in patients with high stroke preventability vs. low/no preventability [4.7 ± 0.29 (n = 28) vs. 3.8 ± 0.21 (n = 90)]. The vast majority of patients with high stroke preventability had inadequately treated atrial fibrillation (85%, 53/62).

Conclusions: Nearly one quarter of stroke patients undergoing mechanical thrombectomy had highly preventable strokes. While stroke preventability showed some relationship to stroke severity at onset and outcome after treatment, preventability had the strongest association with age. These findings emphasize the need for improved stroke prevention in the elderly.