Infarct Growth despite Endovascular Thrombectomy Recanalization in Large Vessel Occlusive Stroke

Impact and determinants of door in-door out time for stroke thrombectomy transfers in a large hub-and-spoke network

INTRODUCTION

The mantra "time is brain" cannot be overstated for patients suffering from acute ischemic stroke. This is especially true for those with large vessel occlusions (LVOs) requiring transfer to an endovascular thrombectomy (EVT) capable center. We sought to evaluate the spoke hospital door in-door out (DIDO) times for patients transferred to our hub center for EVT.

METHODS

Individuals who first presented with LVO to a spoke hospital and were then transferred to the hub for EVT were retrospectively identified from a prospectively maintained database from January 2019 to November 2022. DIDO was defined as the time between spoke hospital door in arrival and door out exit. Baseline characteristics, treatments, and outcomes were compared, dichotomizing DIDO at 90 minutes based in the American Heart Association goal for DIDO ≤90 minutes for 50% of transfers. Multivariable regression analyses were performed for determinants of the 90-day ordinal modified Rankin Scale (mRS) and DIDO.

RESULTS

We identified 194 patients transferred for EVT with available DIDO. The median age was 67 years (IQR 57-80), and 46% were female. The median National Institutes of Health Stroke Scale (NIHSS) was 16 (10-20), 50% were treated with intravenous thrombolysis at a spoke, and TICI 2B-3 reperfusion was achieved in 87% at the hub. The median DIDO was 120 minutes (97-149), with DIDO ≤90 minutes achieved in 18%. DIDO was a significant determinant of 90-day ordinal mRS (B = 0.007, 95% CI = 0.001-0.012, p = 0.013), even when accounting for the last known well-to-spoke door in, spoke door out-to-hub arrival, hub arrival-to-puncture, puncture-to-first pass, age, NIHSS, intravenous thrombolysis, TICI 2B-3, and symptomatic intracranial hemorrhage. Importantly, determinants of DIDO included Black race or Hispanic ethnicity (B = 0.918, 95% CI = 0.010-1.826, p = 0.048), atrial fibrillation or heart failure (B = 0.793, 95% CI = 0.257-1.329, p = 0.004), and basilar LVO location (B = 2.528, 95% CI = 1.154-3.901, p < 0.001).

CONCLUSION

Spoke DIDO was the most important period of time for long-term outcomes of LVO stroke patients treated with EVT. Targets were identified to reduce DIDO and improve patient outcomes.

Ethical Considerations in Endovascular Thrombectomy for Stroke

INTRODUCTION

Stroke is a leading cause of morbidity and mortality globally. Endovascular mechanical thrombectomy is considered for patients with large vessel occlusion stroke presenting up to 24 hours from onset and is being increasingly utilized across diverse clinical contexts. Proactive consideration of distinctive ethical dimensions of endovascular thrombectomy (EVT) can enable stroke care teams to deliver goal-concordant care to appropriately selected patients with stroke but have been underexplored.

METHODS

A narrative review with case examples was conducted.

RESULTS

We explain and critically evaluate the application of foundational bioethical principles and narrative ethics to the practice of EVT, highlight key ethical issues that may emerge in neuroendovascular practice and develop an ethical framework to aid in the responsible use of EVT for people with large-vessel occlusive ischemic stroke.

CONCLUSIONS

EVT for stroke introduces important ethical considerations. Salient challenges include decision-making capacity and informed consent, the telos of EVT, uncertainty, access to care, and resource allocation. An ethical framework focusing on combining patient values and preferences with the best available evidence in the context of a multidisciplinary care team is essential to ensure that the benefits of EVT are responsibly achieved and sustained.

The dilemma of neuroprotection trials in times of successful endovascular recanalization

Background

The "translational roadblock" between successful animal stroke studies and neutral clinical trials is usually attributed to conceptual weaknesses. However, we hypothesized that rodent studies cannot inform the human disease due to intrinsic pathophysiological differences between rodents and humans., i.e., differences in infarct evolution.

Methods

To verify our hypothesis, we employed a mixed study design and compared findings from meta-analyses of animal studies and a retrospective clinical cohort study. For animal data, we systematically searched pubmed to identify all rodent studies, in which stroke was induced by MCAO and at least two sequential MRI scans were performed for infarct volume assessment within the first two days. For clinical data, we included 107 consecutive stroke patients with large artery occlusion, who received MRI scans upon admission and one or two days later.

Results

Our preclinical meta-analyses included 50 studies with 676 animals. Untreated animals had a median post-reperfusion infarct volume growth of 74%. Neuroprotective treatments reduced this infarct volume growth to 23%. A retrospective clinical cohort study showed that stroke patients had a median infarct volume growth of only 2% after successful recanalization. Stroke patients with unsuccessful recanalization, by contrast, experienced a meaningful median infarct growth of 148%.

Conclusion

Our study shows that rodents have a significant post-reperfusion infarct growth, and that this post-reperfusion infarct growth is the target of neuroprotective treatments. Stroke patients with successful recanalization do not have such infarct growth and thus have no target for neuroprotection.

Infarct Evolution on MR-DWI After Thrombectomy in Acute Stroke Patients Randomized to Nerinetide or Placebo: The REPERFUSE-NA1 Study

BACKGROUND AND OBJECTIVES

The neuroprotectant nerinetide has shown promise in reducing infarct volumes in primate models of ischemia reperfusion. We hypothesized that early secondary infarct growth after endovascular therapy (EVT) (1) may be a suitable surrogate biomarker for testing neuroprotective compounds, (2) is feasible to assess in the acute setting using sequential MRI, and (3) can be modified by treatment with nerinetide.

METHODS

REPERFUSE-NA1 was a prospective, multisite MRI substudy of the randomized controlled trial ESCAPE-NA1 (ClinicalTrials.gov NCT02930018) that involved patients with acute disabling large vessel occlusive stroke undergoing EVT within 12 hours of onset who were randomized to receive intravenous nerinetide or placebo. Patients enrolled in REPERFUSE-NA1 underwent sequential MRI <5 hours post-EVT (day 1) and at 24 hours (day 2). The primary outcome was total diffusion-weighted MRI infarct growth early after EVT, defined as the lesion volume difference between day 2 and day 1. The secondary outcome was region-specific infarct growth in different brain tissue compartments. Statistical analyses were performed using the Mann-Whitney U test and multiple linear regression.

RESULTS

Sixty-seven of 71 patients included had MRI of sufficient quality. The median infarct volume post-EVT was 12.98 mL (IQR, 5.93-28.08) in the nerinetide group and 10.80 mL (IQR, 3.11-24.45) in the control group (p = 0.59). Patients receiving nerinetide showed a median early secondary infarct growth of 5.92 mL (IQR, 1.09-21.30) compared with 10.80 mL (interquartile range [IQR], 2.54-21.81) in patients with placebo (p = 0.30). Intravenous alteplase modified the effect of nerinetide on region-specific infarct growth in white matter and basal ganglia compartments. In patients with no alteplase, the infarct growth rate was reduced by 120% (standard error [SE], 60%) in the white matter (p = 0.03) and by 340% (SE, 140%) in the basal ganglia (p = 0.02) in the nerinetide group compared with placebo after adjusting for confounders.

DISCUSSION

This study highlights the potential of using MR imaging as a biomarker to estimate the effect of a neuroprotective agent in acute stroke treatment. Patients with acute large vessel occlusive stroke exhibited appreciable early infarct growth both in the gray matter and the white matter after undergoing EVT. Acknowledging relatively small overall infarct volumes in this study, treatment with nerinetide was associated with slightly reduced percentage infarct growth in the white matter and basal ganglia compared with placebo in patients not receiving intravenous alteplase and had no effect on the total early secondary infarct growth.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov NCT02930018.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that for patients with acute large vessel ischemic stroke undergoing EVT, nerinetide did not significantly decrease early post-EVT infarct growth compared with placebo.

Role of intravenous alteplase on late lesion growth and clinical outcome after stroke treatment

Several acute ischemic stroke mechanisms that cause lesion growth continue after treatment which is detrimental to long-term clinical outcome. The potential role of intravenous alteplase treatment (IVT), a standard in stroke care, in cessing the physiological processes causing post-treatment lesion development is understudied. We analyzed patients from the MR CLEAN-NO IV trial with good quality 24-hour and 1-week follow-up Non-Contrast CT scans. We delineated hypo- and hyper-dense regions on the scans as lesion. We performed univariable logistic and linear regression to estimate the influence of IVT on the presence (growth > 0 ml) and extent of late lesion growth. The association between late lesion growth and mRS was assessed using ordinal logistic regression. Interaction analysis was performed to evaluate the influence of IVT on this association. Of the 63/116 were randomized to included patients, IVT. Median growth was 8.4(-0.88-26) ml. IVT was not significantly associated with the presence (OR: 1.24 (0.57-2.74, p = 0.59) or extent (β = 5.1(-8.8-19), p = 0.47) of growth. Late lesion growth was associated with worse clinical outcome (aOR: 0.85(0.76-0.95), p < 0.01; per 10 ml). IVT did not influence this association (p = 0.18). We did not find evidence that IVT influences late lesion growth or the relationship between growth and worse clinical outcome. Therapies to reduce lesion development are necessary.

Pupillometry in the follow-up of patients undergoing EVT - prediction of space-occupying hemispheric infarction

BACKGROUND

Despite benefits of endovascular treatment (EVT) for large vessel occlusion (LVO) ischemic stroke, space-occupying brain edema (BE) represents a detrimental complication. In critical-care settings, CT-imaging is needed for monitoring these patients. Yet, bed-side techniques with the potential to predict whether patients develop BE or not would facilitate a time- and cost-efficient patient care. We assessed clinical significance of automated pupillometry in the follow-up of patients undergoing EVT.

METHODS

From 10/2018 to 10/2021, neurocritical-care-unit patients were retrospectively enrolled after EVT of anterior circulation LVO. We monitored parameters of pupillary reactivity [light-reflex-latency (Lat), constriction- and redilation-velocities (CV, DV), percentage-change-of-apertures (per-change); NeurOptics-pupilometer®] up to every hour on day 1-3 of ICU stay. BE was defined as midline shift ≥ 5 mm on follow-up imaging 3-5 days after EVT. We calculated mean values of intra-individual differences between successive pairs of parameters (mean-deltas), determined best discriminative cut-off values for BE development (ROC-analyses), and evaluated prognostic performance of pupillometry for BE development (sensitivity/specificity/positive-/negative-predictive-values).

RESULTS

3241 pupillary assessments of 122 patients [67 women, 73 years (61.0-85.0)] were included. 13/122 patients developed BE. Patients with BE had significantly lower CVs, DVs, and smaller per-changes than patients without BE. On day 1 after EVT mean-deltas of CV, DV, and per-changes were significantly lower in patients with than without BE. Positive-predictive-values of calculated thresholds to discriminate both groups were considerably low, yet, we found high negative-predictive-values for CV, DV, per-changes, and mean-deltas (max.: 98.4%).

CONCLUSION

Our data suggest associations between noninvasively detected changes in pupillary reactivity and BE early after LVO-EVT. Pupillometry may identify patients who are unlikely to develop BE and may not need repetitive follow-up-imaging or rescue-therapy.

Clinical Significance and Influencing Factors of Microvascular Tissue Reperfusion After Macrovascular Recanalization

The relevance of impaired microvascular tissue reperfusion despite successful macrovascular angiographic reperfusion (no-reflow) in acute ischemic stroke (AIS) remains controversial. In this study, we aimed to investigate the impact of tissue optimal reperfusion (TOR) and its influencing factors. From December 1, 2020 to December 1, 2021, AIS patients with successful recanalization (modified Thrombolysis in Cerebral Infarction score [mTICI] ≥ 2b) after mechanical thrombectomy (MT) were retrospectively reviewed. Computed tomography perfusion was performed before and after MT. Successful reperfusion was assessed by TOR, defined as > 90% reduction of the Tmax > 6 s lesion volumes between baseline and early follow-up perfusion profiles. The impact of TOR on functional outcomes after successful recanalization and influencing factors for TOR were both investigated. Sixty-three patients were included, including 44 cases in the TOR group and 19 cases in the non-TOR group. The TOR group had a higher rate of favorable outcome (aOR 4.366, 95%CI 1.159-16.445, p = 0.030) and NIHSS improvement (aOR 5.089, 95%CI 1.340-19.322, p = 0.017) than the non-TOR group. Multivariable logistic regression showed baseline glucose (OR 0.648, 95%CI 0.492-0.854, p = 0.002) and mTICI 2c/3 (OR 10.984, 95%CI 2.220-54.343, p = 0.003) predicted TOR in model 1; in model 2, postoperative glucose (OR 0.468, 95%CI 0.278-0.787, p = 0.004) and mTICI 2c/3 (OR 9.436, 95%CI 1.889-47.144, p = 0.006) were predictive. TOR was strongly associated with good functional outcomes after successful recanalization of MT. Higher mTICI grade and lower perioperative glucose level may predict microvascular tissue reperfusion.

In a hub-and-spoke network, spoke-administered thrombolysis reduces mechanical thrombectomy procedure time and number of passes

BACKGROUND

The utility of intravenous thrombolysis (IVT) prior to mechanical thrombectomy (MT) in large vessel occlusion stroke (LVO) is controversial. Some data suggest IVT increases MT technical difficulty. Within our hub-and-spoke telestroke network, we examined how spoke-administered IVT affected hub MT procedure time and pass number.

METHODS

Patients presenting to 25 spoke hospitals who were transferred to the hub and underwent MT from 2018 to 2020 were identified from a prospectively maintained database. MT procedure time, fluoroscopy time, and pass number were obtained from operative reports.

RESULTS

Of 107 patients, 48 received IVT at spokes. Baseline characteristics and NIHSS were similar. The last known well (LKW)-to-puncture time was shorter among IVT patients (4.3 ± 1.9 h vs. 10.5 ± 6.5 h, p < 0.0001). In patients that received IVT, mean MT procedure time was decreased by 18.8 min (50.5 ± 29.4 vs. 69.3 ± 46.7 min, p = 0.02) and mean fluoroscopy time was decreased by 11.3 min (21.7 ± 15.8 vs. 33.0 ± 30.9 min, p = 0.03). Furthermore, IVT-treated patients required fewer MT passes (median 1 pass [IQR 1.0, 1.80] vs. 2 passes [1.0, 2.3], p = 0.0002) and were more likely to achieve reperfusion in ≤2 passes (81.3% vs. 59.3%, p = 0.01). An increased proportion of IVT-treated patients achieved TICI 2b-3 reperfusion after MT (93.9% vs. 83.8%, p = 0.045). There were no associations between MT procedural characteristics and LKW-to-puncture time.

CONCLUSION

Within our network, hub MT following spoke-administered IVT was faster, required fewer passes, and achieved improved reperfusion. This suggests spoke-administered IVT does not impair MT, but instead may enhance it.

Imaging biomarkers for clinical applications in neuro-oncology: current status and future perspectives

Biomarker discovery and development are popular for detecting the subtle diseases. However, biomarkers are needed to be validated and approved, and even fewer are ever used clinically. Imaging biomarkers have a crucial role in the treatment of cancer patients because they provide objective information on tumor biology, the tumor's habitat, and the tumor's signature in the environment. Tumor changes in response to an intervention complement molecular and genomic translational diagnosis as well as quantitative information. Neuro-oncology has become more prominent in diagnostics and targeted therapies. The classification of tumors has been actively updated, and drug discovery, and delivery in nanoimmunotherapies are advancing in the field of target therapy research. It is important that biomarkers and diagnostic implements be developed and used to assess the prognosis or late effects of long-term survivors. An improved realization of cancer biology has transformed its management with an increasing emphasis on a personalized approach in precision medicine. In the first part, we discuss the biomarker categories in relation to the courses of a disease and specific clinical contexts, including that patients and specimens should both directly reflect the target population and intended use. In the second part, we present the CT perfusion approach that provides quantitative and qualitative data that has been successfully applied to the clinical diagnosis, treatment and application. Furthermore, the novel and promising multiparametric MR imageing approach will provide deeper insights regarding the tumor microenvironment in the immune response. Additionally, we briefly remark new tactics based on MRI and PET for converging on imaging biomarkers combined with applications of bioinformatics in artificial intelligence. In the third part, we briefly address new approaches based on theranostics in precision medicine. These sophisticated techniques merge achievable standardizations into an applicatory apparatus for primarily a diagnostic implementation and tracking radioactive drugs to identify and to deliver therapies in an individualized medicine paradigm. In this article, we describe the critical principles for imaging biomarker characterization and discuss the current status of CT, MRI and PET in finiding imaging biomarkers of early disease.

Percent Insular Ribbon Infarction for Predicting Infarct Growth Rate and 90-Day Outcomes in Large-Vessel Occlusive Stroke: Secondary Analysis of Prospective Clinical Trial Data

Background: Insight into the natural history of infarct growth could help identify patients with slowly progressing stroke who may benefit from delayed endovascular thrombectomy (EVT). Objective: To evaluate associations of percent insular ribbon infarction (PIRI) with infarct growth rate (IGR) and 90-day outcomes in patients with large-vessel occlusion (LVO) stroke. Methods: This retrospective study was a secondary analysis of a prior clinical trial that enrolled patients with acute stroke not treated with reperfusion therapies from January 2007 to June 2009. The present analysis evaluated 31 trial patients (median age, 71 years; 12 female, 19 male) with anterior-circulation LVO who underwent serial MRI examinations. Two neuroradiologists independently scored PIRI on presentation MRI examinations based on the ratio of the length of the portion of the insula showing restricted diffusion to the insula's total length using a previously described 0-4 scale; scores were categorized [mild (0-1), moderate (2), or severe (3-4)], and discrepancies were resolved by consensus. Ninety-day modified Rankin Scale (mRS) was obtained. As part of earlier clinical trial analysis, collateral pattern on CTA was classified (symmetric, malignant, other), and infarct volumes were measured on DWI during the initial 48 hours after presentation and on FLAIR at 90 days. Results: Inter-rater agreement for PIRI category was strong (K=0.890). PIRI was mild in 10, moderate in 4, and severe in 17 patients. For mild, moderate, and severe PIRI, median onset-to-presentation IGR was 1.6, 8.5, and 17.5 cc/h (p<.001); median presentation-to-48-hour IGR was 0.3, 0.2, and 1.2 cc/h (p=.005); median 90-day infarct volume was 9.4, 39.8, and 108.6 cc (p=0.01); 90-day mRS ≤2 occurred in 78%, 67%, and 6% of patients (p=.001). In multivariable models controlling for age, ICA occlusion, and collateral pattern, PIRI category independently predicted onset-to-presentation IGR (β=1.5), presentation-to-48-hour IGR (β=1.3), and 90-day mRS ≤2 (OR=0.2). For predicting 90-day mRS ≤2, mild-to-moderate PIRI had sensitivity of 90.0% and specificity of 84.2%; symmetric collateral pattern had sensitivity of 70.0% and specificity of 73.7%. Conclusion: PIRI was independently associated with IGR and 90-day outcome. Clinical Impact: PIRI may help identify patients who could benefit from late-window EVT when requiring transfer to EVT-capable centers.

Brush sign and collateral supply as potential markers of large infarct growth after successful thrombectomy

OBJECTIVES

To investigate the relationships between brush sign and cerebral collateral status on infarct growth after successful thrombectomy.

METHODS

HIBISCUS-STROKE cohort includes acute ischemic stroke patients treated with thrombectomy after MRI triage and undergoing a day-6 MRI including FLAIR images to quantify final infarct volume (FIV). Successful reperfusion was defined as a modified thrombolysis in cerebral infarction score  ≥ 2B. Infarct growth was calculated by subtracting FIV from baseline ischemic core after co-registration and considered large (LIG) when  > 11.6 mL. Brush sign was assessed on T2*-weighted-imaging and collaterals were assessed using the hypoperfusion intensity ratio, which is the volume of Time-To-Tmax (Tmax)  ≥ 10 s divided by the volume of Tmax  ≥  6 s. Good collaterals were defined by a hypoperfusion intensity ratio  < 0.4.

RESULTS

One hundred and twenty-nine patients were included, of whom 45 (34.9%) had a brush sign and 63 (48.8%) good collaterals. Brush sign was associated with greater infarct growth (p = 0.01) and larger FIV (p = 0.02). Good collaterals were associated with a smaller baseline ischemic core (p < 0.001), larger penumbra (p = 0.04), and smaller FIV (p < 0.001). Collateral status was not significantly associated with brush sign (p = 0.20) or with infarct growth (p = 0.67). Twenty-eight (22.5%) patients experienced LIG. Univariate regressions indicated that brush sign (odds ratio (OR) = 4.8; 95% confidence interval (CI): [1.9;13.3]; p = 0.004) and hemorrhagic transformation (OR = 1.7; 95%CI: [1.2;2.6]; p = 0.04) were predictive of LIG. In multivariate regression, only the brush sign remained predictive of LIG (OR = 5.2; 95%CI: [1.8-16.6], p = 0.006).

CONCLUSIONS

Brush sign is a predictor of LIG after successful thrombectomy and cerebral collateral status is not.

KEY POINTS

• Few predictors of ischemic growth are known in ischemic stroke patients achieving successful mechanical thrombectomy. • Our results suggest that the brush sign-a surrogate marker of severe hypoperfusion-is independently associated with large ischemic growth (> 11.6 mL) after successful thrombectomy whereas cerebral collateral status does not.

Symmetric collateral pattern on CTA predicts favorable outcomes after endovascular thrombectomy for large vessel occlusion stroke

Endovascular thrombectomy (EVT) has revolutionized large vessel occlusion (LVO) stroke management, but often requires advanced imaging. The collateral pattern on CT angiograms may be an alternative because a symmetric collateral pattern correlates with a slowly growing, small ischemic core. We tested the hypothesis that such patients will have favorable outcomes after EVT. Consecutive patients (n = 74) with anterior LVOs who underwent EVT were retrospectively analyzed. Inclusion criteria were available CTA and 90-day modified Rankin Scale (mRS). CTA collateral patterns were symmetric in 36%, malignant in 24%, or other in 39%. Median NIHSS was 11 for symmetric, 18 for malignant, and 19 for other (p = 0.02). Ninety-day mRS ≤2, indicating independent living, was achieved in 67% of symmetric, 17% of malignant, and 38% of other patterns (p = 0.003). A symmetric collateral pattern was a significant determinant of 90-day mRS ≤2 (aOR = 6.62, 95%CI = 2.24,19.53; p = 0.001) in a multivariable model that included age, NIHSS, baseline mRS, thrombolysis, LVO location, and successful reperfusion. We conclude that a symmetric collateral pattern predicts favorable outcomes after EVT for LVO stroke. Because the pattern also marks slow ischemic core growth, patients with symmetric collaterals may be suitable for transfer for thrombectomy. A malignant collateral pattern is associated with poor clinical outcomes.

Spoke-administered thrombolysis improves large vessel occlusion early recanalization: the real-world experience of a large academic hub-and-spoke telestroke network

Introduction

Intravenous thrombolysis (IVT) prior to mechanical thrombectomy (MT) for large vessel occlusion (LVO) stroke is increasingly controversial. Recent trials support MT without IVT for patients presenting directly to MT-capable "hub" centers. However, bypassing IVT has not been evaluated for patients presenting to IVT-capable "spoke" hospitals that require hub transfer for MT. A perceived lack of efficacy of IVT to result in LVO early recanalization (ER) is often cited to support bypassing IVT, but ER data for IVT in patients that require interhospital transfer is limited. Here we examined LVO ER rates after spoke-administered IVT in our hub-and-spoke stroke network.

Methods

Patients presenting to 25 spokes before hub transfer for MT consideration from 2018-2020 were retrospectively identified from a prospectively maintained database. Inclusion criteria were pre-transfer CTA-defined LVO, ASPECTS ≥6, and post-transfer repeat vessel imaging.

Results

Of 167 patients, median age was 69 and 51% were female. 76 received spoke IVT (+spokeIVT) and 91 did not (-spokeIVT). Alteplase was the only IVT used in this study. Comorbidities and NIHSS were similar between groups. ER frequency was increased 7.2-fold in +spokeIVT patients [12/76 (15.8%) vs. 2/91 (2.2%), P<0.001]. Spoke-administered IVT was independently associated with ER (aOR=11.5, 95% CI=2.2,99.6, p<0.05) after adjusting for timing of last known well, interhospital transfer, and repeat vessel imaging. Interval NIHSS was improved in patients with ER (median -2 (IQR -6.3, -0.8) vs. 0 (-2.5, 1), p<0.05).

Conclusion

Within our network, +spokeIVT patients had a 7.2-fold increased ER relative likelihood. This real-world analysis supports IVT use in eligible patients with LVO at spoke hospitals before hub transfer for MT.

Understanding Delays in MRI-based Selection of Large Vessel Occlusion Stroke Patients for Endovascular Thrombectomy

PURPOSE

Given the efficacy of endovascular thrombectomy (EVT), optimizing systems of delivery is crucial. Magnetic resonance imaging (MRI) is the gold standard for evaluating tissue viability but may require more time to obtain and interpret. We sought to identify determinants of arrival-to-puncture time for patients who underwent MRI-based EVT selection in a real-world setting.

METHODS

Patients were identified from a prospectively maintained database from 2011-2019 that included demographics, presentations, treatments, and outcomes. Process times were obtained from the medical charts. MRI times were obtained from time stamps on the first sequence. Linear and logistic regressions were used to infer explanatory variables of arrival-to-puncture times and effects of arrival-to-puncture time on functional outcomes.

RESULTS

In this study 192 patients (median age 70 years, 57% women, 12% non-white) underwent MRI-based EVT selection. 66% also underwent computed tomography (CT) at the hub before EVT. General anesthesia was used for 33%. Among the entire cohort, the median arrival-to-puncture was 102 min; however, among those without CT it was 77 min. Longer arrival-to-puncture times independently reduced the odds of 90-day good outcome (∆mRS ≤ 2 from pre-stroke, aOR = 0.990, 95%CI = 0.981-0.999, p = 0.040) when controlling for age, NIHSS, and good reperfusion (TICI 2b-3). Independent determinants of longer arrival-to-puncture were CT plus MRI (β = 0.205, p = 0.003), non-white race/ethnicity (β = 0.162, p = 0.012), coronary disease (β = 0.205, p = 0.001), and general anesthesia (β = 0.364, p < 0.0001).

CONCLUSION

Minimizing arrival-to-puncture time is important for outcomes. Real-world challenges exist in an MRI-based EVT selection protocol; avoiding double imaging is key to saving time. Racial/ethnic disparities require further study. Understanding variables associated with delay will inform protocol changes.

Direct to angio-suite large vessel occlusion transfers achieve faster arrival-to-puncture times and improved outcomes

Introduction

For patients with large vessel occlusion (LVO) stroke, time to treatment with endovascular thrombectomy (EVT) is crucial to prevent infarction and improve outcomes. We sought to evaluate the hub arrival-to-puncture times and outcomes for transferred patients accepted directly to the angio-suite (LVO2OR) versus those accepted through the emergency department (ED) in a hub-and-spoke telestroke network.

Methods

Consecutive patients transferred for EVT with spoke CTA-confirmed LVO, spoke ASPECTS >6, and LKW-to-hub arrival <6 hours were identified. Our LVO2OR protocol began implementation in January 2017. The LVO2OR cohort includes patients who underwent EVT from July 2017 to October 2020; the ED cohort includes those from January 2011 to December 2016. Hub arrival-to-puncture time and 90-day modified Rankin Scale (mRS) were prospectively recorded.

Results

The LVO2OR cohort was comprised of 91 patients and the ED cohort 90. LVO2OR patients had more atrial fibrillation (AF, 51% vs 32%, p=0.02) and more M2 occlusions (27% vs 10%, p=0.01). LVO2OR patients had faster median hub arrival-to-puncture time (11 vs 92 minutes, p<0.001), faster median telestroke consult-to-puncture time (2.4 vs 3.6 hours, p<0.001), greater TICI 2b-3 reperfusion (92% vs 69%, p<0.001), and greater 90-day mRS <2 (35% vs 21%, p=0.04). In a multivariable model, LVO2OR significantly increased the odds of 90-day mRS <2 (aOR 2.77, 95%CI 1.07,7.20; p=0.04) even when controlling for age, baseline mRS, AF, NIHSS, M2 location, and TICI 2b-3.

Conclusion

In a hub-and-spoke telestroke network, accepting transferred patients directly to the angio-suite was associated with dramatically reduced hub arrival-to-puncture time and may lead to improved 90-day outcomes. Direct-to-angio-suite protocols should continue to be evaluated in other regions and telestroke models.

Postoperative neutrophil-lymphocyte ratio predicts unfavorable outcome of acute ischemic stroke patients who achieve complete reperfusion after thrombectomy

Purpose

Only approximately half of anterior circulation large vessel occlusion (LVO) patients receiving endovascular treatment (EVT) have a favorable outcome. The aim of this study was to explore the association of dynamic inflammatory markers (i.e., neutrophil to lymphocyte ratios, NLR, measured at different times after EVT) as well as other potential influencing factors with unfavorable outcome among acute ischemic stroke (AIS) patients who achieved complete reperfusion after EVT.

Methods

Patients treated with EVT for LVO between January 2019 to December 2021 were prospectively enrolled. Complete reperfusion was defined as modified thrombolysis in cerebral infarction (mTICI) grade 3. A modified Rankin scale at 90 days (mRS90) of 3-6 was defined as unfavorable outcome (i.e., futile reperfusion). A logistic regression analysis was performed with unfavorable outcome as a dependent variable. The receiver operating characteristic (ROC) curve and the area under the curve (AUC) were then used to determine the diagnostic values of NLR and other relevant factors.

Results

170 patients with complete reperfusion (mTICI 3) were included in this study. Unfavorable outcome was observed in 70 (41.2%). Higher NLR within 24h (p=0.017) and at 3-7d (p=0.008) after EVT were an independent risk factors for unfavorable outcome at 3 months. In addition, older age, higher NIHSS scores, poor collaterals, and general anesthesia were independent predictors of unfavorable outcomes. When accounting for NLR, the diagnostic efficiency improved compared to conventional characteristics.

Conclusion

Our findings suggest that advanced age, increased stroke severity, poor collaterals, general anesthesia, and NLR are independent predictors for an unfavorable clinical outcome following complete reperfusion after EVT. Neuroinflammation may merit particular attention in future studies.

Characterizing reasons for stroke thrombectomy ineligibility among potential candidates transferred in a hub-and-spoke network

Background

Access to endovascular thrombectomy (EVT) is relatively limited. Hub-and-spoke networks seek to transfer appropriate large vessel occlusion (LVO) candidates to EVT-capable hubs. However, some patients are ineligible upon hub arrival, and factors that drive transfer inefficiencies are not well described. We sought to quantify EVT transfer efficiency and identify reasons for EVT ineligibility.

Methods

Consecutive EVT candidates presenting to 25 spokes from 2018-2020 with pre-transfer CTA-defined LVO and ASPECTS ≥6 were identified from a prospectively maintained database. Outcomes of interest included hub EVT, reasons for EVT ineligibility, and 90-day modified Rankin Scale (mRS) ≤2.

Results

Among 258 patients, the median age was 70 years (IQR 60-81); 50% were female. 56% were ineligible for EVT after hub arrival. Cited reasons were large established infarct (49%), mild symptoms (33%), recanalization (6%), distal occlusion (5%), sub-occlusive lesion (3%), and goals of care (3%). Late window patients [last known well (LKW) >6 hours] were more likely to be ineligible (67% vs 43%, P<0.0001). EVT ineligible patients were older (73 vs 68 years, p=0.04), had lower NIHSS (10 vs 16, p<0.0001), longer LKW-hub arrival time (8.4 vs 4.6 hours, p<0.0001), longer spoke Telestroke consult-hub arrival time (2.8 vs 2.2 hours, p<0.0001), and received less intravenous thrombolysis (32% vs 45%, p=0.04) compared to eligible patients. EVT ineligibility independently reduced the odds of 90-day mRS≤2 (aOR=0.26, 95%CI=0.12,0.56; p=0.001) when controlling for age, NIHSS, and LKW-hub arrival time.

Conclusions

Among patients transferred for EVT, there are multiple reasons for ineligibility upon hub arrival, with most excluded for infarct growth and mild symptoms. Understanding factors that drive transfer inefficiencies is important to improve EVT access and outcomes.

Prognostic value of ASPECTS on post-treatment diffusion-weighted imaging for acute ischemic stroke patients after endovascular thrombectomy: comparison with infarction volume

OBJECTIVES

To assess the prognostic value of Alberta Stroke Program Early Computed Tomography Score (ASPECTS) on post-treatment diffusion-weighted imaging (DWI) for acute ischemic stroke (AIS) patients after endovascular thrombectomy (EVT) and compare it with that of infarction volume.

METHODS

Ninety-eight consecutive AIS patients who underwent EVT and post-treatment DWI were retrospectively enrolled. ASPECTS and infarction volume were evaluated based on post-treatment DWI, respectively. Good clinical outcome was defined as modified Rankin Scale score of 0-2 at 90 days. Predictors of good clinical outcome were evaluated using univariate and multivariate logistic regression analysis. Prognostic value of post-treatment DWI ASPECTS and infarction volume were assessed and compared using receiver-operating-characteristic curves and the DeLong method.

RESULTS

Favorable outcome was achieved in 62 (63.3%) patients. A strong correlation was found between post-treatment DWI ASPECTS and infarction volume (ρ = -0.847). Due to strong correlation and potential collinearity, two multivariate logistic regression models were respectively developed which included post-treatment DWI ASPECTS or infarction volume. As a result, post-treatment DWI ASPECTS (OR, 2.401; 95%CI, 1.567-3.678; p < 0.001) and infarction volume (OR, 0.982; 95%CI, 0.846-0.998; p = 0.002) were both independent predictors of good clinical outcome. Setting post-treatment DWI ASPECTS ≥ 6 as a cut-off value, optimal performance (AUC = 0.836; sensitivity, 87.1%; specificity, 66.7%) could be obtained in predicting good clinical outcome, which was comparable with that of infarction volume (cut-off volume, ≤ 94.87 ml; AUC = 0.821; sensitivity, 90.3%; specificity, 55.6%).

CONCLUSIONS

Post-treatment DWI ASPECTS might be a potential surrogate of infarction volume and be effective in predicting the clinical outcome of AIS patients after EVT.

KEY POINTS

• Post-treatment DWI ASPECTS correlated significantly with infarction volume. • A post-treatment DWI ASPECTS ≥ 6 best predicts good outcomes for AIS patients after EVT. • Post-treatment DWI ASPECTS has the potential in substituting infarction volume in predicting the clinical outcome of AIS patients.

Association of Infarct Topography and Outcome After Endovascular Thrombectomy in Patients With Acute Ischemic Stroke

BACKGROUND AND OBJECTIVES

The care of patients with large vessel occlusion (LVO) stroke has been revolutionized by endovascular thrombectomy (EVT). While EVT has a large effect size, most patients treated with EVT remain disabled or die within 90 days. A better understanding of outcomes may influence EVT selection criteria, novel therapies, and prognostication. We sought to identify associations between outcomes and brain regions involved in ischemic lesions.

METHODS

For this cohort study, consecutive patients with LVO who were treated with EVT and underwent post-EVT MRI were identified from a tertiary referral center (2011-2019). Acute ischemic lesions were manually segmented from diffusion-weighted imaging and spatially normalized. Individual lesions were parcellated (atlas-defined 94 cortical regions, 14 subcortical nuclei, 20 white matter tracts) and reduced to 10 essential lesion patterns with the use of unsupervised dimensionality reduction techniques. Ninety-day modified Rankin Scale (mRS) score (>2) was modeled via bayesian regression, taking the 10 lesion patterns as inputs and controlling for lesion size, age, sex, acute NIH Stroke Scale (NIHSS) score, alteplase, prior stroke, intracerebral hemorrhage, and good reperfusion (Thrombolysis in Cerebral Infarction 2b-3). In comparative analyses, 90-day mRS score was modeled considering covariates only, and compartment-wise relevances for acute stroke severity and 90-day mRS score were evaluated.

RESULTS

There were 151 patients with LVO identified (age 68 ± 15 years, 52% female). The median NIHSS score was 16 (interquartile range 13-20); 56% had mRS score >2. Lesion locations predictive of 90-day mRS score involved bilateral but left hemispherically more pronounced precentral and postcentral gyri, insular and opercular cortex, and left putamen and caudate (area under the curve 0.91, highest probability density interval [HPDI] covering 90% certainty 0.90-0.92). The lesion location model outperformed the simpler model relying on covariates only (bayesian model comparison of 97% weight to the model with vs 3% weight to the model without lesion location). While lesions affecting subcortical nuclei had the highest relevance for stroke severity (posterior distribution mean 0.75, 90% HPDI 0.256-1.31), lesions affecting white matter tracts had the highest relevance for 90-day mRS score (0.656, 90% HPDI 0.0864-1.12).

DISCUSSION

These data describe the significance for outcomes of specific brain regions involved in ischemic lesions on MRI after EVT. Future work in additional datasets is needed to confirm these granular findings.

Radiomic signature of DWI-FLAIR mismatch in large vessel occlusion stroke

BACKGROUND AND PURPOSE

Ischemic diffusion-weighted imaging-fluid-attenuated inversion recovery (DWI-FLAIR) mismatch may be useful in guiding acute stroke treatment decisions given its relationship to onset time and parenchymal viability; however, it relies on subjective grading. Radiomics is an emerging image quantification methodology that may objectively represent continuous image characteristics. We propose a novel radiomics approach to characterize DWI-FLAIR mismatch.

METHODS

Ischemic lesions were visually graded for FLAIR positivity (absent, subtle, obvious) among consecutive large vessel occlusion stroke patients who underwent hyperacute MRI. Radiomic features were extracted from within the lesions on DWI and FLAIR. The DWI-FLAIR mismatch radiomics signature was built with features systematically selected by a cross-validated ElasticNet linear regression model of mismatch.

RESULTS

We identified 103 patients with mean age 68 ± 16 years; 63% were female. FLAIR hyperintensity was absent in 25%, subtle in 55%, and obvious in 20%. Inter-rater agreement for visual grading was moderate (Κ = .58). The radiomics signature of DWI-FLAIR mismatch included native FLAIR histogram kurtosis and local binary pattern-filtered FLAIR gray-level cluster shade; both correlated with visual grading (ρ = -.42, p < .001 and ρ = .40, p < .001, respectively).

CONCLUSIONS

Radiomics can describe DWI-FLAIR mismatch and may provide objective, continuous biomarkers for infarct evolution using clinical-grade images. These novel biomarkers may prove useful for treatment decisions and future research.

Sex-specific differences in presentations and determinants of outcomes after endovascular thrombectomy for large vessel occlusion stroke

INTRODUCTION

Sex-specific differences in ischemic stroke outcomes are prevalent. We sought to investigate sex differences in the determinants of reperfusion and functional outcomes after endovascular thrombectomy (EVT) for emergent large vessel occlusion ischemic stroke (ELVO).

METHODS

Patients presenting to a single referral center with an anterior circulation ELVO that underwent EVT from 2011 to 2019 were included in this retrospective analysis. Sex differences in history, presentation, adequate reperfusion (TICI 2b-3), and 90-day good outcome [delta modified Rankin Scale (mRS) ≤ 2 from pre-stroke] were examined. Multivariable logistic regression analyses were performed to assess sex-specific associations with outcomes.

RESULTS

Three hundred and eighty-one consecutive ELVO patients were identified. Women (N = 193) were older (75 vs 64 years, p < 0.0001), had more pre-stroke disability (17% vs 9%, p = 0.032), more atrial fibrillation (41% vs 30%, p = 0.033), but less carotid atherosclerosis (8% vs 16%, p = 0.027). Rates of TICI 2b-3 and good outcome were similar between sexes. Carotid atherosclerosis (OR 0.315, 95% CI 0.130, 0.762) and dissection (OR 0.124, 95% CI 0.027, 0.569) independently decreased the odds of TICI 2b-3 among men but not women. Older age, more severe stroke, and not achieving TICI 2b-3 independently decreased the odds of good outcome among both sexes, while prior stroke (OR 0.258, 95% CI 0.083, 0.797) and hemorrhagic transformation (OR 0.111, 0.021, 0.592) were determinants exclusive to men.

CONCLUSION

In a real-world analysis of ELVO stroke patients treated with EVT, we found that despite advanced age and more pre-stroke disability, women have comparable reperfusion rates and functional outcomes compared to men. Sex-specific determinants of reperfusion and functional outcome were identified that require further study.

Symmetric CTA Collaterals Identify Patients with Slow-progressing Stroke Likely to Benefit from Late Thrombectomy

Background Understanding ischemic core growth rate (IGR) is key in identifying patients with slow-progressing large vessel occlusion (LVO) stroke who may benefit from delayed endovascular thrombectomy (EVT). Purpose To evaluate whether symmetric collateral pattern at CT angiography (CTA) can help to identify patients with low IGR and small 24-hour diffusion-weighted MRI ischemic core volume in patients with LVO not treated with reperfusion therapies. Materials and Methods In this secondary analysis of clinical trial data from before EVT became standard of care from January 2007 to June 2009, patients with anterior proximal LVO not treated with reperfusion therapies were evaluated. All patients underwent admission CTA and at least three MRI examinations at four time points over 48 hours. Arterial phase CTA collaterals at presentation were categorized as symmetric, malignant, or other. Diffusion-weighted MRI ischemic core volume and IGR at multiple time points were determined. The IGR at presentation was defined as follows: (ischemic core volume in cubic centimeters)/(time since stroke symptom onset in hours). Multivariable analyses and receiver operator characteristic analyses were used. Results This study evaluated 31 patients (median age, 71 years; interquartile range, 61-81 years; 19 men) with median National Institutes of Health Stroke Scale (NIHSS) score of 13. Collaterals were symmetric (45%; 14 of 31), malignant (13%; four of 31), or other (42%; 13 of 31). Median ischemic core volume was different between collateral patterns at all time points. Presentation was as follows: symmetric, 16 cm³; other, 69 cm³; and malignant, 104 cm³ (P < .001). At 24 hours, median ischemic core volumes were as follows: symmetric, 28 cm³; other, 156 cm³; and malignant, 176 cm³ (P < .001). Median IGR was also different, and most pronounced at presentation: symmetric, 4 cm³ per hour; other, 17 cm³ per hour; and malignant, 20 cm³ per hour (P < .001). After multivariable adjustment, independent determinants of higher presentation IGR included only higher NIHSS (parameter estimate [β = 0.20; 95% CI: 0.05, 0.36; P = .008) and worse collaterals (β = -2.90; 95% CI: -4.31, -1.50; P < .001). The only independent determinant of 24-hour IGR was worse collaterals (β = -2.03; 95% CI: -3.28, -0.78; P = .001). Symmetric collaterals had sensitivity of 87% (13 of 15) and specificity of 94% (15 of 16) for 24-hour ischemic core volume less than 50 cm³ (area under the receiver operating characteristic curve, 0.92; 95% CI: 0.81, 1.00; P < .001). Conclusion In patients with large vessel occlusion not treated with reperfusion therapies, symmetric collateral pattern at CT angiography was common and highly specific for low ischemic core growth rate and small 24-hour ischemic core volume as assessed at diffusion-weighted MRI. After further outcome studies, collateral status at presentation may prove useful in triage for endovascular thrombectomy, especially when MRI and CT perfusion are unavailable. Clinical trial registration no. NCT00414726. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Messina in this issue.

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.

Infarct Growth despite Successful Endovascular Reperfusion in Acute Ischemic Stroke: A Meta-analysis

BACKGROUND

Infarct volume inversely correlates with good recovery in stroke. The magnitude and predictors of infarct growth despite successful reperfusion via endovascular treatment are not known.

PURPOSE

We aimed to summarize the extent of infarct growth in patients with acute stroke who achieved successful reperfusion (TICI 2b-3) after endovascular treatment.

DATA SOURCES

We performed a systematic review and meta-analysis by searching MEDLINE and Google Scholar for articles published up to October 31, 2020.

STUDY SELECTION

Studies of >10 patients reporting baseline and post-endovascular treatment infarct volumes on MR imaging were included. Only patients with TICI 2b-3 were included. We calculated infarct growth at a study level as the difference between baseline and follow-up MR imaging infarct volumes.

DATA ANALYSIS

Our search yielded 345 studies, and we included 10 studies reporting on 973 patients having undergone endovascular treatment who achieved successful reperfusion.

DATA SYNTHESIS

The mean baseline infarct volume was 19.5 mL, while the mean final infarct volume was 37.5 mL. A TICI 2b reperfusion grade was achieved in 24% of patients, and TICI 2c or 3 in 76%. The pooled mean infarct growth was 14.8 mL (95% CI, 7.9-21.7 mL). Meta-regression showed higher infarct growth in studies that reported higher baseline infarct volumes, higher rates of incomplete reperfusion (modified TICI 2b), and longer onset-to-reperfusion times.

LIMITATIONS

Significant heterogeneity among studies was noted and might be driven by the difference in infarct growth between early- and late-treatment studies.

CONCLUSIONS

These results suggest considerable infarct growth despite successful endovascular treatment reperfusion and call for a faster workflow and the need for specific therapies to limit infarct growth.

Treatment Approaches and Outcomes for Acute Anterior Circulation Stroke Patients with Tandem Lesions

OBJECTIVES

Endovascular thrombectomy (EVT) has revolutionized stroke care for large vessel occlusions (LVOs). However, over half treated remain functionally disabled or die. Patients with tandem lesions, or severe stenosis/occlusion of the cervical internal carotid artery (ICA) with intracranial LVO, may have technical EVT challenges and worse outcomes. We sought to compare treatments and outcomes for patients with anterior circulation tandem lesions versus isolated LVOs.

MATERIALS AND METHODS

Consecutive tandem lesion and isolated intracranial LVO patients were identified at a single center. Demographics, medical history, presentations, treatments, and outcomes were collected and analyzed.

RESULTS

From 381 EVT patients, 62 had tandem lesions related to atherosclerosis (74%) or dissection (26%). Compared to isolated intracranial LVOs, they were younger (63 vs 70, p = 0.003), had less atrial fibrillation (13% vs 40%, p < 0.0001), less adequate reperfusion (TICI 2b-3, 58% vs 82%, p < 0.0001), more intracranial hemorrhage (ICH, 13% vs 5%, p = 0.037), but similar 90-day functional independence (mRS 0-2, 34% vs 43%, p = 0.181). The cervical ICA was treated before intracranial EVT (57%), after (13%), not acutely (22%), or was inaccessible (8%). Acute cervical ICA treatments were stenting (57%) or angioplasty alone (13%). Neither acute stenting nor order of treatment was associated with outcomes (TICI 2b-3, ICH, or 90-day mRS 0-2). Among acutely stented, neither alteplase nor antiplatelets were associated with outcomes or stent patency.

CONCLUSIONS

Tandem lesions were associated with less reperfusion, more ICH, but similar 90-day functional independence. No treatment approach was associated with outcomes. These data illustrate the technical challenges of tandem lesion treatment and underscore the importance of developing new approaches.

White Matter Acute Infarct Volume After Thrombectomy for Anterior Circulation Large Vessel Occlusion Stroke is Associated with Long Term Outcomes

OBJECTIVES

Despite the proven efficacy of endovascular thrombectomy (EVT) for large vessel occlusion stroke, over half treated remain functionally disabled or die. Infarct topography may have implications for prognostication, patient selection, and the development of tissue-specific neuroprotective agents. We sought to quantify white matter injury in anterior circulation acute infarcts post-EVT to understand its significance and identify its determinants.

MATERIALS AND METHODS

Demographics, history, presentations, and outcomes for consecutive patients treated with EVT were recorded in a prospectively maintained database at a single center. Acute infarct masks were coregistered to standard space. Standard atlases of white matter, cortex, and basal ganglia were used to determine region-specific infarct volumes.

RESULTS

167 individuals were identified with median age 69 years and 53% women. 85% achieved adequate reperfusion (TICI 2b-3) after EVT; 43% achieved 90-day functional independence (mRS 0-2). Median infarct volumes were 45cc (IQR 18-122) for total, 17cc (6-49) for white matter, 21cc (4-53) for cortex, and 5cc (1-8) for basal ganglia. The odds of 90-day mRS 0-2 were reduced in patients with larger white matter infarct volume (cc, OR=0.89, 95%CI=0.81-0.96), independent of cortex infarct volume, basal ganglia infarct volume, age, NIHSS, and TICI 2b-3 reperfusion. Reperfusion-to-MRI time was associated with white matter infarct volume (hr, β=0.119, p=0.017), but not cortical or basal ganglia infarct volume.

CONCLUSIONS

These data quantitatively describe region-specific infarct volumes after EVT and suggest the clinical relevance of white matter infarct volume as a predictor of long-term outcomes. Further study is warranted to examine delayed white matter infarction and the significance of specific white matter tracts.