Impact of Cerebral Revascularization on Pial Collateral Flow in Patients With Unilateral Moyamoya Disease Using Quantitative Magnetic Resonance Angiography.

BACKGROUND AND OBJECTIVES: Moyamoya disease (MMD) is a chronic steno-occlusive disease of the intracranial circulation that depends on neoangiogenesis of collateral vessels to maintain cerebral perfusion and is primarily managed with cerebral revascularization surgery. A quantitative assessment of preoperative and postoperative collateral flow using quantitative magnetic resonance angiography with noninvasive optimal vessel analysis (NOVA) was used to illustrate the impact of revascularization on cerebral flow distribution. METHODS: A retrospective review of patients with unilateral MMD who underwent direct, indirect, or combined direct/indirect cerebral revascularization surgery was conducted between 2011 and 2020. Using NOVA, flow was measured at the anterior cerebral artery (ACA), ACA distal to the anterior communicating artery (A2), middle cerebral artery (MCA), posterior cerebral artery (PCA), and PCA distal to the posterior communicating artery (P2). Pial flow (A2 + P2) and collateral flow (ipsilateral [A2 + P2])-(contralateral [A2 + P2]) were measured and compared before and after revascularization surgery. Total hemispheric flow (MCA + A2 + P2) with the addition of the bypass graft flow postoperatively was likewise measured. RESULTS: Thirty-four patients with unilateral MMD underwent cerebral revascularization. Median collateral flow significantly decreased from 68 to 39.5 mL/min (P = .007) after bypass. Hemispheres with maintained measurable bypass signal on postoperative NOVA demonstrated significant reduction in median collateral flow after bypass (P = .002). Median total hemispheric flow significantly increased from 227 mL/min to 247 mL/min (P = .007) after bypass. Only one patient suffered an ipsilateral ischemic stroke, and no patients suffered a hemorrhage during follow-up. CONCLUSION: NOVA measurements demonstrate a reduction in pial collateral flow and an increase in total hemispheric flow after bypass for MMD, likely representing a decrease in leptomeningeal collateral stress on the distal ACA and PCA territories. Further studies with these measures in larger cohorts may elucidate a role for NOVA in predicting the risk of ischemic and hemorrhagic events in MMD.

A bibliometric analysis of tenecteplase research utilizing a commonly used citation index.

BACKGROUND AND PURPOSE: Tenecteplase is increasingly being used as a first-line treatment for acute ischemic stroke after several randomized studies demonstrated its safety and efficacy, resulting in a massive increase in the number of published studies on this topic. Our aim was to investigate the most impactful authors and relevant journals that have been instrumental in validating this treatment, in hopes of identifying objective research trends that may assist scientists, health organizations, and funding agencies to collaborate and plan future avenues of research. METHODS: Using the search terms "Tenecteplase" and "Tenecteplase" AND "Stroke," 2683 and 1150 references were queried, respectively, using the abstract and citation database, Scopus. Scopus Citation Analysis was used to categorize the countries and authors who produced the most research. Metadata was retrieved and transferred to bibliographic visualization software, VOSviewer, for co-authorship and co-occurrence analyses to identify trends in tenecteplase research. RESULTS: Data visualization software identified three tenecteplase research clusters - myocardial infarction, pulmonary embolism, and acute ischemic stroke. Our bibliographic analysis graphically identified that ischemic stroke currently leads both myocardial infarction and pulmonary embolism in annual publications pertaining to tenecteplase therapy, and further pinpointed perfusion imaging and wake-up strokes as the most relevant areas of study. The United States led all countries in tenecteplase publications, including exclusively stroke studies. The European Heart Journal led all journals in overall publications, while Stroke led all journals in stroke-related studies. CONCLUSIONS: Through the use of bibliographic analysis and data visualization, we identified major articles and journals that reflected and shaped the current landscape of tenecteplase; recognized authors who engaged in tenecteplase research as it progressed from cardiopulmonary disease to stroke; and postulated future avenues of research.

Time-driven activity-based costing (TDABC) of direct-to-angiography pathway for acute ischemic stroke patients with suspected large vessel occlusion.

INTRODUCTION: Direct-to-angiography (DTA) is a novel care pathway for endovascular treatment (EVT) of acute ischemic stroke (AIS) that has been shown to reduce time-to-treatment and improve clinical outcomes for EVT-eligible patients. The institutional costs of adopting the DTA pathway and the many factors affecting costs have not been studied. In this study, we assess the costs and main cost drivers associated with the DTA pathway compared to the conventional CT pathway for patients presenting with AIS and suspected LVO in the anterior circulation. METHODS: Time driven activity based costing (TDABC) model was used to compare costs of DTA and conventional pathways from the healthcare institution perspective. Process mapping was used to outline all activities and resources (personnel, equipment, materials) needed for each step in both pathways. The cost model was developed using our institutional patient database and average New York state wages for personnel costs. Total, incremental and proportional costs were calculated based on institutional and patient factors affecting the pathways. RESULTS: DTA pathway accrued additional $82,583.61 (9%) in total costs compared to the conventional approach for all AIS patients. For EVT-ineligible patients, the DTA pathway incurred additional $82,964.37 (76%) in total costs compared to the CT pathway. For EVT eligible patients, the total and per-patient costs were greater in the CT pathway by $380.76 (0.04%) and $5.60 (0.04%) respectively. CONCLUSION: As the DTA pathway incurred additional $82,964.37 for EVT-ineligible patients, appropriate patient selection criteria are needed to avoid transferring EVT-ineligible patients to the angiography suite.

Gender-Based Disparity in Acute Stroke Imaging Utilization and the Impact on Treatment and Outcomes: 2012 to 2021.

INTRODUCTION: Prior studies have revealed significant socio-economic disparities in neuro-imaging and treatment utilization for patients with acute ischemic stroke (AIS). In this study, we sought to evaluate whether a sex-based disparity exists in neuro-imaging and to determine its etiology and association with acute treatment and outcomes. MATERIALS AND METHODS: This was a retrospective study of consecutive patients with AIS admitted to a comprehensive stroke center between 2012 and 2021. Patient demographic and clinical characteristics, neuro-imaging, acute treatment, and early clinical outcomes were extracted from the electronic medical records. Trend analysis, bivariate analysis of patient characteristics by sex, and multivariable logistic regression analyses were conducted. RESULTS: Of the 7,540 AIS episodes registered from 2012 to 2021, 47.9% were female patients. After adjusting for demographic, clinical, and temporal factors, significantly higher utilization of CTA was found for male patients (odds ratio = 1.20 [95% confidence interval 1.07-1.34]), particularly from socio-economically advantaged groups, and in years 2015 and 2019, representing the years endovascular thrombectomy recommendations changed. Despite this, male patients had significantly lower intravenous thrombolysis utilization (odds ratio = 0.83 [95% confidence interval 0.71-0.96]) and similar endovascular thrombectomy rates as female patients. There were no significant sex differences in early clinical outcomes, and no relevant clinical or demographic factors explained the CT angiography utilization disparity. CONCLUSION: Despite higher CT angiography utilization in socio-economically advantaged male patients with AIS, likely overutilization due to implicit biases following guideline updates, the rates of acute treatment, and early clinical outcomes were unaffected.

Acute ischemic stroke outcomes in patients with COVID-19: a systematic review and meta-analysis.

BACKGROUND: Although patients with COVID-19 have a higher risk of acute ischemic stroke (AIS), the impact on stroke outcomes remains uncertain. AIMS: To determine the clinical outcomes of patients with AIS and COVID-19 (AIS-COVID+). METHODS: We performed a systematic review and meta-analysis following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. Our protocol was registered with the International Prospective Register of Systematic Reviews (CRD42020211977). Systematic searches were last performed on June 3, 2021 in EMBASE, PubMed, Web-of-Science, Scopus, and CINAHL Databases. INCLUSION CRITERIA: (1) studies reporting outcomes on AIS-COVID+; (2) original articles published in 2020 or later; (3) study participants aged ≥18 years. EXCLUSION CRITERIA: (1) case reports with <5 patients, abstracts, review articles; (2) studies analyzing novel interventions. Risk of bias was assessed using the Mixed Methods Appraisal Tool. Random-effects models estimated the pooled OR and 95% confidence intervals (95% CI) for mortality, modified Rankin Scale (mRS) score, length of stay (LOS), and discharge disposition. RESULTS: Of the 43 selected studies, 46.5% (20/43) reported patients with AIS without COVID-19 (AIS-COVID-) for comparison. Random-effects model included 7294 AIS-COVID+ and 158 401 AIS-COVID-. Compared with AIS-COVID-, AIS-COVID+ patients had higher in-hospital mortality (OR=3.87 (95% CI 2.75 to 5.45), P<0.001), less mRS scores 0-2 (OR=0.53 (95% CI 0.46 to 0.62), P<0.001), longer LOS (mean difference=4.21 days (95% CI 1.96 to 6.47), P<0.001), and less home discharge (OR=0.31 (95% CI 0.21 to 0.47), P<0.001). CONCLUSIONS: Patients with AIS-COVID had worse outcomes, with almost fourfold increased mortality, half the odds of mRS scores 0-2, and one-third the odds of home discharge. These findings confirm the significant impact of COVID-19 on early stroke outcomes.

Reducing Door-In to Door-Out Time for Patients Receiving a Mechanical Thrombectomy Using AutoLaunch Protocol.

Background: Door-in to door-out (DIDO) time for large vessel occlusion (LVO) stroke is an emerging stroke performance measure. Initial presentation at a non-Comprehensive Stroke Center (CSC) requires a transfer process that minimizes delays. Our objective was to assess whether DIDO time for stroke patients was reduced after implementation of an AutoLaunch protocol for interfacility transfers. Methods: This was a pre-post analysis of an AutoLaunch protocol for all acute stroke patients transferred to a CSC for mechanical thrombectomy. The distribution of DIDO times between patients transferred via the AutoLaunch and traditional dispatch protocols were compared. Results: We evaluated 92 interfacility transfers, with 22 utilizing the AutoLaunch protocol and 70 utilizing traditional dispatch. Among AutoLaunch transfers, the median DIDO time was 85 minutes (IQR: 71, 133), while the median DIDO time among the traditional transfers was 109 minutes (IQR, 84, 144) (p=0.044). Conclusion: Implementation of an AutoLaunch protocol for patients with suspected LVO was associated with a reduction in DIDO time to CSCs. Further studies should evaluate patient outcomes based on transfer strategies.

Atrial Fibrillation In Patients With Stroke Attributed to Large- or Small-Vessel Disease: 3-Year Results From the STROKE AF Randomized Clinical Trial.

Importance: The STROKE AF study found that in patients with prior ischemic stroke attributed to large-artery atherosclerotic disease (LAD) or small-vessel occlusive disease (SVD), 12% developed AF over 1 year when monitored with an insertable cardiac monitor (ICM). The occurrence over subsequent years is unknown. Objectives: To compare the rates of AF detection through 3 years of follow-up between an ICM vs site-specific usual care in patients with prior ischemic stroke attributed to LAD or SVD. Design, Setting, and Participants: This multicenter, randomized (1:1) clinical trial took place at 33 sites in the US with enrollment between April 2016 and July 2019 and 3-year follow-up through July 2022. Eligible patients were aged 60 years or older, or aged 50 to 59 years with at least 1 additional stroke risk factor and had an index ischemic stroke attributed to LAD or SVD within 10 days prior to ICM insertion. Of the 496 patients enrolled, 492 were randomized and 4 were excluded. Interventions: ICM monitoring vs site-specific usual care. Main Outcomes and Measures: The prespecified long-term outcome of the trial was AF detection through study follow-up (up to 3 years). AF was defined as an episode lasting more than 30 seconds, adjudicated by an expert committee. Results: In total, 492 patients were randomized and included in the analyses (median [IQR] age, 66 [60-74] years; 307 men [62.4%] and 185 women [37.6%]), of whom 314 completed 3-year follow-up (63.8%). The incidence rate of AF at 3 years was 21.7% (46 patients) in the ICM group vs 2.4% (5 patients) in the control group (hazard ratio, 10.0; 95% CI, 4.0-25.2; P < .001). Conclusions and Relevance: Patients with ischemic stroke attributed to LAD or SVD face an increasing risk of AF over time and most of the AF occurrences are not reliably detected by standard medical monitoring methods. One year of negative monitoring should not reassure clinicians that patients who have experienced stroke will not develop AF over the next 2 years. Trial Registration: ClinicalTrials.gov Identifier: NCT02700945.

Hyperperfusion syndrome after superficial temporal artery-middle cerebral artery bypass for non-moyamoya steno-occlusive disease.

BACKGROUND AND OBJECTIVES: Stroke is a major cause of morbidity and mortality worldwide, and intracranial stenoses increase the risk for stroke. Superficial temporal artery to middle cerebral artery bypass can be beneficial in selected patients with non-moyamoya steno-occlusive disease, however data is limited regarding the postoperative occurrence of hyperperfusion syndrome in this population. This case series describes the outcomes and complications, including hyperperfusion, in these patients who underwent bypass. METHODS: This is a retrospective review of bypass procedures done for medically refractory intracranial stenosis at a single institution by a single surgeon between 2014 and 2021. RESULTS: 30 patients underwent 33 bypass procedures for unequivocal non-moyamoya steno-occlusive disease. All patients had immediate bypass patency on post-operative day one. Major perioperative complications (9%) included one stroke and two cases of hyperperfusion syndrome. Minor perioperative complications (12%) included two seizures, one superficial wound infection and one deep vein thrombosis. Modified Rankin Score improved in 20 patients (74%), worsened in one patient (4%), and remained stable in seven patients (22%) at the last follow up. Twenty-three patients (85%) had scores ≤ 2. The recurrent stroke rate was 3% at 30 days and 7% at two years. The bypass patency rate at one year was 87.5%. CONCLUSION: In this series, bypass for patients with medically refractory non-moyamoya steno-occlusive disease was well tolerated and effective, with overall favorable outcomes. The occurrence of hyperperfusion syndrome is rare but significant and should be considered in post-operative management of this population.

Comparative outcomes of the treatment of unruptured paraophthalmic aneurysms in the era of flow diversion.

BACKGROUND: Paraophthalmic aneurysms present a challenge to surgeons and their ideal management remains up for debate. We studied recent outcomes of these lesions in a single center. METHODS: A retrospective chart review of all patients undergoing treatment for paraophthalmic aneurysms from 2017-2019 was performed. Factors including patient demographics, aneurysm characteristics, treatment modality, radiographic treatment outcome, clinical outcome, and length of stay were collected, and bivariate analysis was performed. RESULTS: In total 84.5% (82/97) of aneurysms were treated endovascularly and 15.5% (15/97) surgically. In the surgery cohort, there were three transient perioperative complications (20%) and one minor postoperative complication (6.7%). Complete aneurysm occlusion or near complete (<2mm residual) was achieved in 100% (15/15). All but one patient had mRS ≤1 at the last follow-up. In the endovascular group, 78.1% (64/82) underwent flow diversion alone. Endovascular treatment was associated with a 4.9% (4/82) rate of periprocedural complications: 3 transient events, and 1 death, and a 3.7% (3/82) rate of delayed complications: 2 transient vision changes, and one death. Rate of total occlusion was 87.8% (72/82). 76 patients (92.7%) had mRS ≤1 at the last follow-up. Length of stay was significantly shorter in the endovascular group (3.4 days vs. 7.0 days) [p < 0.001]. CONCLUSIONS: This series demonstrates similar safety to previously reported series as well as the efficacy of both surgical clipping and endovascular embolization of paraophthalmic aneurysms. Rate of complications and treatment efficacy were similar in both groups although this represents a single institution series not generalizable to all centers.

Association between the degree of vertebrobasilar stenosis, location, infarction pattern, and QMRA flow state.

BACKGROUND AND PURPOSE: We aimed to investigate the relationship between the degree and location of vertebrobasilar stenosis and quantitative magnetic resonance angiography (QMRA) distal flow. METHODS: We retrospectively reviewed patients who presented with acute ischemic stroke with ≥50% stenosis of the extracranial or intracranial vertebral or basilar arteries, and QMRA performed within 1 year of stroke. Standardized techniques were used to measure stenosis and to dichotomize vertebrobasilar distal flow status. Patients were grouped based on the involved artery and the severity of disease. All p-values were calculated using chi-squared analysis and Fisher exact test with statistical significance defined as p < .05. RESULTS: Sixty-nine patients met study inclusion, consisting of 31 with low distal flow and 38 with normal distal flow. The presence of severe stenosis or occlusion was 100% sensitive, but only 47% predictive and 26% specific of a low distal flow state. Bilateral vertebral disease was only 55% sensitive but was 71% predictive and 82% specific of a low-flow state and was five times and nearly three times more likely to result in a low-flow state compared to unilateral vertebral disease (14%) and isolated basilar disease (28%), respectively. CONCLUSIONS: Severe stenosis of ≥70% may mark the minimal threshold required to cause hemodynamic insufficiency in the posterior circulation, but nearly half of these patients may remain hemodynamically sufficient. Bilateral vertebral stenosis resulted in a fivefold increase in QMRA low distal flow status compared to unilateral vertebral disease. These results may have implications in the design of future treatment trials of intracranial atherosclerotic disease.

Cost-effectiveness of remote robotic mechanical thrombectomy in acute ischemic stroke.

OBJECTIVE: Clinical outcomes following endovascular thrombectomy (EVT) for acute ischemic stroke (AIS) treatment are highly time sensitive. Remote robotic (RR)-EVT systems may be capable of mitigating time delays in patient transfer from a primary stroke center (PSC) to a comprehensive/thrombectomy-capable stroke center. However, health economic evidence is needed to assess the costs and benefits of an RR-EVT system. Therefore, the authors of this study aimed to determine whether performing RR-EVT in suspected AIS patients at a PSC as opposed to standard of care might translate to cost-effectiveness over a lifetime. METHODS: An economic evaluation study was performed from a US healthcare perspective, combining decision analysis and Markov modeling methods over a lifetime horizon to evaluate the cost-effectiveness of RR-EVT in suspected AIS patients at a PSC compared to the standard-of-care approach. Total expected costs and quality-adjusted life-years (QALYs) were estimated. RESULTS: In the cost-effectiveness analysis, RR-EVT yielded greater effectiveness per patient (4.05 vs 3.88 QALYs) and lower costs (US$321,269 vs US$321,397) than the standard-of-care approach. Owing to these lower costs and greater health benefits, RR-EVT was the dominant cost-effective strategy. After initiation of an RR-EVT system, the average costs per year were similar (or slightly reduced), according to this simulation. Sensitivity analyses revealed that RR-EVT remains cost-effective in a wide variety of time delays and cost assumptions. In a one-way sensitivity analysis, RR-EVT remained the most cost-effective strategy when time delays were greater than 2.5 minutes, its complication rate did not exceed 37%, and costs were lower than $54,081. When the cost of the RR-EVT strategy ranged from $19,340 to $54,081 and its complication rate varied from 15% to 37%, the RR-EVT strategy remained the most cost-effective throughout the two ranges. RR-EVT was also the most cost-effective strategy even when its cost doubled (to approximately $40,000) and time delays exceeded 20 minutes. In a probabilistic sensitivity analysis, RR-EVT was the long-term cost-effective strategy in 89.8% of iterations at a willingness-to-pay threshold of $100,000/QALY. CONCLUSIONS: This analysis suggests that RR-EVT as an innovative solution to expedite EVT is cost-effective. An RR-EVT system could potentially extend access to care in underserved communities and rural areas, as well as improve care for socioeconomically disadvantaged populations affected by health inequities.

Predictors of Atrial Fibrillation in Patients With Stroke Attributed to Large- or Small-Vessel Disease: A Prespecified Secondary Analysis of the STROKE AF Randomized Clinical Trial.

Importance: The Stroke of Known Cause and Underlying Atrial Fibrillation (STROKE AF) trial found that approximately 1 in 8 patients with recent ischemic stroke attributed to large- or small-vessel disease had poststroke atrial fibrillation (AF) detected by an insertable cardiac monitor (ICM) at 12 months. Identifying predictors of AF could be useful when considering an ICM in routine poststroke clinical care. Objective: To determine the association between commonly assessed risk factors and poststroke detection of new AF in the STROKE AF cohort monitored by ICM. Design, Setting, and Participants: This was a prespecified analysis of a randomized (1:1) clinical trial that enrolled patients between April 1, 2016, and July 12, 2019, with primary follow-up through 2020 and mean (SD) duration of 11.0 (3.0) months. Eligible patients were selected from 33 clinical research sites in the US. Patients had an index stroke attributed to large- or small-vessel disease and were 60 years or older or aged 50 to 59 years with at least 1 additional stroke risk factor. A total of 496 patients were enrolled, and 492 were randomly assigned to study groups (3 did not meet inclusion criteria, and 1 withdrew consent). Patients in the ICM group had the index stroke within 10 days before insertion. Data were analyzed from October 8, 2021, to January 28, 2022. Interventions: ICM monitoring vs site-specific usual care (short-duration external cardiac monitoring). Main Outcomes and Measures: The ICM device automatically detects AF episodes 2 or more minutes in length; episodes were adjudicated by an expert committee. Cox regression multivariable modeling included all parameters identified in the univariate analysis having P values <.10. AF detection rates were calculated using Kaplan-Meier survival estimates. Results: The analysis included the 242 participants randomly assigned to the ICM group in the STROKE AF study. Among 242 patients monitored with ICM, 27 developed AF (mean [SD] age, 66.6 [9.3] years; 144 men [60.0%]; 96 [40.0%] women). Two patients had missing baseline data and exited the study early. Univariate predictors of AF detection included age (per 1-year increments: hazard ratio [HR], 1.05; 95% CI, 1.01-1.09; P = .02), CHA2DS2-VASc score (per point: HR, 1.54; 95% CI, 1.15-2.06; P = .004), chronic obstructive pulmonary disease (HR, 2.49; 95% CI, 0.86-7.20; P = .09), congestive heart failure (CHF; with preserved or reduced ejection fraction: HR, 6.64; 95% CI, 2.29-19.24; P < .001), left atrial enlargement (LAE; HR, 3.63; 95% CI, 1.55-8.47; P = .003), QRS duration (HR, 1.02; 95% CI, 1.00-1.04; P = .04), and kidney dysfunction (HR, 3.58; 95% CI, 1.35-9.46; P = .01). In multivariable modeling (n = 197), only CHF (HR, 5.06; 95% CI, 1.45-17.64; P = .05) and LAE (HR, 3.32; 1.34-8.19; P = .009) remained significant predictors of AF. At 12 months, patients with CHF and/or LAE (40 of 142 patients) had an AF detection rate of 23.4% vs 5.0% for patients with neither (HR, 5.1; 95% CI, 2.0-12.8; P < .001). Conclusions and Relevance: Among patients with ischemic stroke attributed to large- or small-vessel disease, CHF and LAE were associated with a significantly increased risk of poststroke AF detection. These patients may benefit most from the use of ICMs as part of a secondary stroke prevention strategy. However, the study was not powered for clinical predictors of AF, and therefore, other clinical characteristics may not have reached statistical significance. Trial Registration: ClinicalTrials.gov Identifier: NCT02700945.

Cost-effectiveness of endovascular thrombectomy in acute stroke patients with large ischemic core.

BACKGROUND: Evidence has shown that endovascular thrombectomy (EVT) treatment improves clinical outcomes. Yet, its benefit remains uncertain in patients with large established infarcts as defined by ASPECTS (Alberta Stroke Program Early CT Score) <6. This study evaluates the cost-effectiveness of EVT, compared with standard care (SC), in acute ischemic stroke (AIS) patients with ASPECTS 3-5. METHODS: An economic evaluation study was performed combining a decision tree and Markov model to estimate lifetime costs (2021 US$) and quality-adjusted life years (QALYs) of AIS patients with ASPECTS 3-5. Incremental cost-effectiveness ratios (ICERs), net monetary benefits (NMBs), and deterministic one-way and two-way sensitivity analyses were performed. Probabilistic sensitivity analyses were also performed to evaluate the robustness of our model. RESULTS: Compared with SC, the cost-effectiveness analyses revealed that EVT yields higher lifetime benefits (2.20 QALYs vs 1.41 QALYs) with higher lifetime healthcare cost per patient ($285 861 vs $272 954). The difference in health benefits between EVT and SC was 0.79 QALYs, equivalent to 288 additional days of healthy life per patient. Even though EVT is more costly than SC alone, it is still cost-effective given better outcomes with ICER of $16 239/QALY. The probabilistic sensitivity analyses indicated that EVT was the most cost-effective strategy in 98.8% (9882 of 10 000) of iterations at the willingness-to-pay threshold of $100 000 per QALY. CONCLUSIONS: The results of this study suggest that EVT is cost-effective in AIS patients with a large ischemic core (ASPECTS 3-5), compared with SC alone over the patient's lifetime.

Stroke mechanisms in adult moyamoya disease: The association between infarction patterns and quantitative magnetic resonance angiography flow state.

INTRODUCTION: Flow augmentation is the mainstay treatment for moyamoya disease as hemodynamic failure is believed to be the dominant mechanism. We aimed to investigate the mechanisms of stroke in moyamoya disease by assessing the relationship between infarction patterns and quantitative magnetic resonance angiography flow state. METHODS: A retrospective study of adult patients with suspected MMD who presented with MRI confirmed acute ischemic stroke predating or following QMRA by a maximum of six months between 2009 and 2021 was conducted. Of the 177 consecutive patients with MMD who received QMRA, 35 patients, consisting of 41 hemispheres, met inclusion criteria. Flow-status was dichotomized into low-flow and normal-flow state based on previously established criteria. RESULTS: Mixed infarction pattern was the most frequent finding (70.7 %), followed by embolic (17.1 %), perforator (7.3 %), and internal borderzone (IBZ) (4.9 %). Infarction patterns were further dichotomized into IBZ+ (internal borderzone alone or mixed) and IBZ- (no internal borderzone constituent). Low-flow states were not significantly more frequent in the IBZ+ compared to IBZ- population (48.4 % vs. 20.0 %, p = 0.14). Ipsilateral posterior cerebral artery fractional flow was significantly higher with IBZ+ compared to IBZ- (345.0 % vs. 214.7 %, p = 0.04). CONCLUSION: Mixed infarction pattern was the most common pattern of infarction in patients with moyamoya disease, implying hypoperfusion and thromboembolism are codominant stroke mechanisms. An association between ICA flow status and infarction pattern was not found, although QMRA evidence of more robust posterior cerebral artery leptomeningeal collaterals was found in patients with a hypoperfusion contribution to their stroke mechanism.

Does Advanced Imaging Aid in the Preoperative Evaluation of Patients With Moyamoya Disease?

Background Moyamoya disease is characterized by progressive nonatherosclerotic stenosis and eventual occlusion of the supraclinoid cerebral arteries with the associated development of abnormal collateral vessels. Treatment of moyamoya disease revolves around restoring cerebral blood flow (CBF) distal to the steno-occlusive disease. Numerous modalities can be used to assess hemodynamic parameters. We sought to determine the impact of preoperative imaging on surgical decision-making. Methods A retrospective review was performed of all patients seen with the diagnosis of moyamoya. Patients were grouped on presentation based on CT/MRI findings of infarction, hemorrhage, or normal. Patients who did not have all of the preoperative tests were excluded. Preoperative radiological results were dichotomized as either normal or abnormal. Results During a five-year period, 34 patients with moyamoya met the inclusion criteria. All patients had an abnormal magnetic resonance angiography (MRA) Non-invasive Optimal Vessel Analysis (NOVA; VasSol, Inc, River Forest, IL). Three patients had normal initial MRI. All symptomatic patients had abnormal preoperative workup and underwent revascularization, as all were found to have abnormal single photon emission computed tomography (SPECT). The only occasion where the decision for surgery or type of surgery was influenced by imaging findings was in patients with nonclassical or minimal symptoms. Conclusion Although hemodynamic imaging studies can aid in establishing a preoperative baseline of CBF and cerebral vascular reserve (CVR) for follow-up studies, the true implication of these tests in the preoperative evaluation of clearly symptomatic moyamoya patients is debatable. In asymptomatic/mildly symptomatic patients, hemodynamic studies are necessary to determine the need for treatment. For symptomatic patients, surgery can be performed without an exhaustive and costly preoperative hemodynamic evaluation.

Contrast-associated acute kidney injury in acute ischemic stroke patients following multi-dose iodinated contrast.

BACKGROUND AND OBJECTIVE: lthough intravenous contrast in neuroimaging has become increasingly important in selecting patients for stroke treatment, clinical concerns remain regarding contrast-associated acute kidney injury (CA-AKI). Given the increasing utilization of CT angiography and/or perfusion coupled with cerebral angiography, the purpose of this study was to assess the association of CA-AKI and multi-dose iodinated contrast in acute ischemic stroke (AIS) patients. MATERIALS AND METHODS: etrospective review of AIS patients at a comprehensive stroke center was performed from January 2018 to December 2019. Data collection included patient demographics, stroke risk factors, stroke severity, discharge disposition, modified Rankin Scale, contrast type/volume, and creatinine levels (baseline, 48-72 h). CA-AKI was defined as creatinine increase ≥ 25 % from baseline. Bivariate analyses and multivariable logistic regression models were implemented to compare AIS patients with multi-dose and single-dose contrast. RESULTS: Of 440 AIS patients, 215 (48.9 %) were exposed to a single-dose contrast, and 225 (51.1 %) received multi-dose. In single-dose patients, CA-AKI at 48/72 h was 9.7 %/10.2 % compared to 8.0 %/8.9 % in multi-dose patients. Multi-dose patients were significantly more likely to receive a higher volume of contrast (mean 142.1 mL versus 80.8 mL; p < 0.001), but there was no significant difference in their creatinine levels or CA-AKI. NIHSS score (OR=1.08, 95 % CI=[1.04,1.13]), and patient transfer from another hospital (OR=3.84, 95 % CI=[1.94,7.62]) were significantly associated with multi-dose contrast. CONCLUSIONS: No significant association between multi-dose iodinated contrast and CA-AKI was seen in AIS patients. Concerns of CA-AKI should not deter physicians from pursuing timely and appropriate contrast-enhanced neuroimaging that may optimize treatment outcomes in AIS patients.

Neuroimaging in acute ischemic stroke: Trends, disparities, and clinical impact.

INTRODUCTION: Clinical studies over the past decade expanded the eligibility criteria for endovascular therapy, with advanced imaging selection and new devices leading to higher rates of good outcomes. Herein, we explore the current trends in neuroimaging, associated factors, and impact on treatment and clinical outcomes. MATERIALS AND METHODS: This is a retrospective study of consecutive acute ischemic stroke patients, admitted to a comprehensive stroke center from 2016 to 2020. Patient characteristics, including age, sex, race, arrival method, admission National Institutes of Health Stroke Scale score and last known well to arrival time; imaging and treatment utilization; and discharge outcome by modified Rankin Scale and disposition were extracted from medical records. Trend and multivariable logistic regression analyses were performed, and trends were stratified by patient characteristics. RESULTS: Of 4,125 acute ischemic stroke episodes, 15.1% received intravenous thrombolysis only, and 7.5% received endovascular thrombectomy from 2016 to 2020. Neuroimaging utilization trends significantly increased for computed tomography angiography (CTA) (48.7% to 75.2%, p < 0.001) and computed tomography perfusion (CTP) (0.26% to 32.9%, p < 0.001), and decreased for magnetic resonance angiography (MRA) (43.2% to 24.7%, p < 0.001). These trends held after adjusting for patient characteristics. Endovascular thrombectomy and intravenous thrombolysis were significantly more common in patients with CTA and CTP (p < 0.0001), and these treatments were associated with good clinical outcomes after controlling for patient characteristics. CONCLUSION: We found significantly increased trends in CTA and CTP imaging, which were associated with endovascular thrombectomy and intravenous thrombolysis utilization, in acute ischemic stroke patients from 2016 to 2020.

Hypoperfusion Intensity Ratio is Associated with Stroke Mechanism in Patients Undergoing Mechanical Thrombectomy.

BACKGROUND: Hypoperfusion Intensity Ratio (HIR), defined as Tmax >10s/Tmax >6s on computed tomography perfusion (CTP), and stroke mechanisms have been independently correlated with angiographic collaterals and patient outcomes. Slowly developing atherosclerotic stenosis may foster collateral development, whereas cardioembolic occlusion may occur before collaterals mature. We hypothesized that favorable HIR is associated with large artery atherosclerosis (LAA) stroke mechanism and good clinical outcome. METHODS: Retrospective study of consecutive endovascularly-treated stroke patients with intracranial ICA or MCA M1/M2 occlusions, who underwent CTP before intervention, between January 2018 and August 2021. Patients were dichotomized into LAA+ or LAA- based on presence of LAA on angiography. HIR was dichotomized into favorable (HIR+) or unfavorable (HIR-) groups based on published thresholds. Good early outcome was defined as discharge mRS of 0-2. Bivariate and multivariable logistic regression were performed. RESULTS: 143 patients met inclusion. 21/143 were LAA+ (15%) and 65/143 (45%) were HIR+. HIR+ was significantly more frequent in LAA+ patients (67% vs. 42%, p= 0.035). Controlling for demographics, stroke severity, imaging findings, and medical comorbidities, LAA+ remained independently associated with HIR+ (OR 5.37 [95% CI 1.43 - 20.14]; p=0.013) as did smaller infarction core volume (<30 mL of CBF <30%: OR 7.92 [95% CI 2.27 - 27.64]; p = 0.001). HIR+ was not associated with good clinical outcome. CONCLUSIONS: Large artery atherosclerosis was independently associated with favorable HIR in patients undergoing mechanical thrombectomy. While favorable HIR was associated with smaller pre-treatment core infarcts, reflecting more robust collaterals, it was not associated with good clinical outcome.

Updated Trends, Disparities, and Clinical Impact of Neuroimaging Utilization in Ischemic Stroke in the Medicare Population: 2012 to 2019.

OBJECTIVE: The purpose of this study was to update trends, investigate sociodemographic disparities, and evaluate the impact on mortality of stroke neuroimaging across the United States from 2012 to 2019. METHODS: Retrospective cohort study using CMS Medicare 5% Research Identifiable Files, representing consecutive ischemic stroke emergency department or hospitalized patients aged ≥65 years. A total of 85,547 stroke episodes with demographic and clinical information were analyzed using Cochran-Mantel-Haenszel tests and logistic regression. Outcome measures were neuroimaging (CT angiography [CTA], CT perfusion [CTP], MRI, MR angiography [MRA]) utilization, acute treatment (endovascular thrombectomy [EVT] and intravenous thrombolysis [IVT]), and mortality while in the hospital and at 30 days and 1 year post discharge. RESULTS: Significantly increasing utilization trends for CTA (250%), CTP (428%) and MRI (18%), and a decreasing trend for MRA (-33%) were observed from 2012 to 2019 (P < .0001). Controlling for covariates in the logistic regression models, CTA and CTP were significantly associated with higher EVT and IVT utilization. Although CTA, MRI, and MRA were associated with lower mortality, CTP was associated with higher mortality post discharge. Less neuroimaging was performed in rural patients; older patients (≥80 years) had lower utilization of CTA, MRI, and MRA; female patients had lower rates of CTA; and Black patients had lower utilization of CTA and CTP. CONCLUSIONS: CTA and CTP utilization increased in the Medicare ischemic stroke population from 2012 to 2019 and both were associated with greater EVT and IVT use. However, disparities exist in neuroimaging utilization across all demographic groups, and further understanding of the root causes of these disparities will be crucial to achieving equity in stroke care.