Large Vessel Occlusion Patients Research Articles

Predictors of futile recanalization in nonagenarians treated with mechanical thrombectomy: a multi-center observational study.

There is a lack of data regarding patients aged 90years or older undergoing mechanical thrombectomy and their predictors of futile recanalization. We sought to evaluate the predictors of futile recanalization in patients ≥ 90years with large vessel occlusion undergoing mechanical thrombectomy. This multi-center observational retrospective study included patients ≥ 90years consecutively treated with mechanical thrombectomy in four thrombectomy capable centers between January 1st, 2016 and 30th March 2023. Futile recanalization was defined as large vessel occlusion patients experiencing a 90-day poor outcome (mRS 3-6) despite successful recanalization (mTICI ≥ 2b) after mechanical thrombectomy. Our cohort included 139 patients ≥ 90years with acute ischemic stroke due to anterior circulation large vessel occlusion treated with mechanical thrombectomy. One hundred seventeen of one hundred thirty-nine patients ≥ 90years who achieved successful recanalization were included in the analysis (seventy-six female (64.9%)), of whom thirty-one (26.49%) experienced effective recanalization and eighty-six (73.51%) experienced futile recanalization. Patients with futile recanalization had higher NIHSS on admission (p < 0.001); they were less frequently treated with intravenous thrombolysis (p = 0.048), had more often general anesthesia (p = 0.011), and longer door to groin puncture delay (p = 0.002). Univariable regression analysis showed that use of intravenous thrombolysis (0.29, 95% CI 0.02-0.79, p = 0.034) and site of occlusion distal vs proximal (0.34, 95% CI 0.11-0.97, p = 0.044) were associated with reduced probability of futile recanalization while NIHSS on admission (1.29, 95% CI 1.16-1.45, p < 0.001), NIHSS at 24h (1.15, 95% CI 1.07-1.25, p = 0.002), type of anesthesia used (4.18, 95% CI 1.57-11.08, p = 0.004), and door to groin puncture time (1.02, 95% CI 1.00-1.05, p = 0.005) were associated with increased probability of futile recanalization. Multivariable regression analysis showed that use of intravenous thrombolysis (0.44, 95% CI 0.09-0.88, p = 0.039) was associated with reduced probability of futile recanalization. Our study seems to suggest that mechanical thrombectomy with intravenous thrombolysis is associated with reduced probability of futile recanalization in a multi-center cohort of patients aged 90years or older.

The impacts of venous outflow profiles on outcomes among large vessel occlusion patients receiving endovascular treatment in the late window.

To investigate the association between venous outflow (VO) profiles and outcomes among acute ischemic stroke caused by anterior circulation large vessel occlusion (AIS-LVO) patients who had undergone endovascular treatment (EVT) in the late window of 6-24 h from stroke onset. This was a post-hoc analysis of our preceding RESCUE-BT trial, with findings validated in an external cohort. Baseline computed tomographic angiography (CTA) was performed to assess VO using the Cortical Vein Opacification Score (COVES). The primary clinical outcome was functional independence at 90 days (modified Rankin Scale score of 0-2). The adjusted odd ratio (aOR) and confidence interval (CI) were obtained from multivariable logistic regressions. A total of 440 patients were included in the present study. After identifying the cutoff of COVES by marginal effects approach, enrolled patients were divided into the favorable VO group (COVES 4-6) and the poor VO (COVES 0-3) group. Multivariable logistic regression analysis showed that favorable VO (aOR 2.25; 95% CI 1.31-3.86; p = 0.003) was associated with functional independence. Similar results were detected in the external validation cohort. Among those with poor arterial collateralization, favorable VO was still an independent predictor of functional independence (aOR 2.09; 95% CI 1.06-4.10; p = 0.032). The robust VO profile indicated by COVES 4-6 could promote the frequency of functional independence among AIS-LVO patients receiving EVT in the late window, and the prognostic value of VO was independent of the arterial collateral status. The robust venous outflow profile was a valid predictor for functional independence among AIS-LVO patients receiving EVT in the late window (6-24 h) and the predictive role of venous outflow did not rely on the status of arterial collateral circulation.

HEMERA‐1 CarboxyHEMoglobin OxygEn Delivery for Evascularization in Acute Stroke: A Prospective, Randomized Phase 1 Clinical Trial

BACKGROUND PP‐007 is a polyethylene glycol (PEG)ylated bovine carboxyhemoglobin gas transfer molecule with pleotropic cytoprotective effects, vasodilatation, plasma expansion, and optimization of oxygen delivery. Rodent middle cerebral artery occlusion models have demonstrated that PP‐007 increases blood flow in the collateral circulation and reduces final infarct volumes, supporting a potential role as neuroprotective agent in acute ischemic stroke. We aim to evaluate the safety and feasibility of PP‐007 as an adjunctive treatment to mechanical thrombectomy (MT) in patients with stroke secondary to large vessel occlusion. METHODS HEMERA‐1 (CarboxyHEMoglobin OxygEn delivery for Revascularization in Acute Stroke) was a multicenter, prospective, randomized, controlled phase 1 clinical trial. Anterior circulation large vessel occlusion patients were assigned in a 3:1 ratio to receive either PP‐007 (320 mg/kg: 30 min bolus followed by 2‐h infusion) plus MT or MT alone within 24 hours after symptom onset. Comprehensive safety evaluation was performed by independent Data Monitoring Safety Board and Imaging Core Lab. RESULTS From October 1, 2021 to June 30, 2022, a total of 17 patients were recruited. Age, baseline National Institutes of Health Stroke Scale score, and Alberta Stroke Program Early CT Score were 74.8±12.7 years, 17.3±4.2, and 7.9±1.8, respectively. Twelve patients were randomized to PP‐007 plus MT, 1 was randomized but not treated, 4 patients were randomized to MT alone. Recanalization of the occluded vessel was achieved in all patients. A transient systolic blood pressure increase (20–40 mm Hg) during the bolus was observed in all PP‐007 patients without any clinical consequences. There were no other safety concerns. CONCLUSION No significant safety concerns were identified for the adjunctive use of PP‐007 in patients undergoing MT. (The study was funded by Prolong Pharmaceuticals. REGISTRATION URL: https://www.clinicaltrials.gov ; Unique identifier: NCT04677777.

Large vessel occlusive stroke with milder baseline severity shows better collaterals and reduced harm from thrombectomy transfer delays.

Patients with large vessel occlusion (LVO) stroke presenting with milder baseline clinical severity are common and require endovascular thrombectomy. However, such patients are difficult to recognize using pre-hospital severity-based triage tools and therefore are likely to require a secondary inter-hospital transfer if transported to a non-thrombectomy center. Given the potential for milder severity to represent better underlying cerebrovascular collateral circulation, it is unknown whether transfer delays are still associated with poorer post-stroke outcomes in this patient group. We primarily aimed to examine whether the harmful effect of inter-hospital transfer delay for thrombectomy was different for LVO patients with mild or severe deficits. Secondarily, we also investigated whether imaging markers of collateral circulation were different between severity groups. Registry data from two large Australian thrombectomy centers were used to identify all directly presenting and secondarily transferred LVO patients undergoing thrombectomy, divided into those with lower (NIHSS < 10) and higher (NIHSS ⩾ 10) baseline deficits. The primary outcome was the functional independence or return to baseline defined as modified Rankin Scale 0-2 or baseline at 90 days. Patients with complete baseline CT-perfusion data were analyzed for imaging markers of collateral circulation by baseline severity group. A total of 1210 LVO patients undergoing thrombectomy were included, of which 273 (22.6%) had lower baseline severity. Despite similar thrombolysis and recanalization rates, transferred patients had lower odds of achieving the primary outcome compared to the primary presentation to a thrombectomy center, where baseline severity was higher (adjusted odds ratio (aOR) 0.759 (95% CI 0.576-0.999)), but not when severity was lower (aOR 1.357 (95% CI 0.764-2.409), p-interaction = 0.122). In the imaging analysis of 436 patients, those with milder severity showed smaller median ischemic core volumes (12.6 (IQR 0.0-17.9) vs 27.5 (IQR 6.5-37.1) mL, p < 0.001)), higher median perfusion mismatch ratio (10.8 (IQR 4.8-54.5) vs 6.6 (IQR 3.5-16.5), p < 0.001), and lower median hypoperfusion intensity ratio (0.25 (IQR 0.18-0.38) vs 0.40 (IQR 0.22-0.57), p < 0.001). Patients receiving secondary inter-hospital transfer for thrombectomy had poorer outcomes compared to those presenting directly to a thrombectomy center if baseline deficits were severe, but this difference was not observed when baseline deficits were milder. This result may potentially be due to our secondary findings of significantly improved collateral circulation markers in lower-severity LVO patients. As such, failure of pre-hospital screening tools to detect lower-severity LVO patients for pre-hospital bypass to a thrombectomy center may not necessarily deleteriously affect outcome. Anonymized data not published within this article will be made available on request from any qualified investigator.

Deep learning-assisted diagnosis of large vessel occlusion in acute ischemic stroke based on four-dimensional computed tomography angiography.

To develop deep learning models based on four-dimensional computed tomography angiography (4D-CTA) images for automatic detection of large vessel occlusion (LVO) in the anterior circulation that cause acute ischemic stroke. This retrospective study included 104 LVO patients and 105 non-LVO patients for deep learning models development. Another 30 LVO patients and 31 non-LVO patients formed the time-independent validation set. Four phases of 4D-CTA (arterial phase P1, arterial-venous phase P2, venous phase P3 and late venous phase P4) were arranged and combined and two input methods was used: combined input and superimposed input. Totally 26 models were constructed using a modified HRNet network. Assessment metrics included the areas under the curve (AUC), accuracy, sensitivity, specificity and F1 score. Kappa analysis was performed to assess inter-rater agreement between the best model and radiologists of different seniority. The P1 + P2 model (combined input) had the best diagnostic performance. In the internal validation set, the AUC was 0.975 (95%CI: 0.878-0.999), accuracy was 0.911, sensitivity was 0.889, specificity was 0.944, and the F1 score was 0.909. In the time-independent validation set, the model demonstrated consistently high performance with an AUC of 0.942 (95%CI: 0.851-0.986), accuracy of 0.902, sensitivity of 0.867, specificity of 0.935, and an F1 score of 0.901. The best model showed strong consistency with the diagnostic efficacy of three radiologists of different seniority (k = 0.84, 0.80, 0.70, respectively). The deep learning model, using combined arterial and arterial-venous phase, was highly effective in detecting LVO, alerting radiologists to speed up the diagnosis.

Thrombus Imaging Characteristics to Predict Early Recanalization in Anterior Circulation Large Vessel Occlusion Stroke.

The early management of transferred patients with a large vessel occlusion (LVO) stroke could be improved by identifying patients who are likely to recanalize early. We aim to predict early recanalization based on patient clinical and thrombus imaging characteristics. We included 81 transferred anterior-circulation LVO patients with an early recanalization, defined as the resolution of the LVO or the migration to a distal location not reachable with endovascular treatment upon repeated radiological imaging. We compared their clinical and imaging characteristics with all (322) transferred patients with a persistent LVO in the MR CLEAN Registry. We measured distance from carotid terminus to thrombus (DT), thrombus length, density, and perviousness on baseline CT images. We built logistic regression models to predict early recanalization. We validated the predictive ability by computing the median area-under-the-curve (AUC) of the receiver operating characteristics curve for 100 5-fold cross-validations. The administration of intravenous thrombolysis (IVT), longer transfer times, more distal occlusions, and shorter, pervious, less dense thrombi were characteristic of early recanalization. After backward elimination, IVT administration, DT and thrombus density remained in the multivariable model, with an AUC of 0.77 (IQR 0.72-0.83). Baseline thrombus imaging characteristics are valuable in predicting early recanalization and can potentially be used to optimize repeated imaging workflow.

Portable cerebral blood flow monitor to detect large vessel occlusion in patients with suspected stroke

BackgroundEarly detection of large vessel occlusion (LVO) facilitates triage to an appropriate stroke center to reduce treatment times and improve outcomes. Prehospital stroke scales are not sufficiently sensitive, so we...

Time-dependent systolic blood pressure within 72h after endovascular treatment in large vessel occlusion stroke.

The association of systolic blood pressure (SBP) and ischemic stroke outcome has recently been proved to be varied at different time points within 72h after acute ischemic stroke onset; however, the specific status of how SBP affects prognosis at different time points within 72h after endovascular treatment (EVT) among patients with large vessel occlusion (LVO) remains unclear. Consecutive LVO patients treated with EVT were enrolled in our study. BP data were collected at eight time points (1, 2, 4, 8, 16, 24, 48, and 72h post-EVT). Outcome measure of interest was functional dependence, which was defined as mRS >2 at 90 days. A total of 406 LVO patients treated with EVT from 2016 to 2022 were included. At 16h after EVT, the relationship between SBP and functional dependence showed a nonlinear association. At other time points after EVT, SBP had linear relationships with functional dependence. Furthermore, higher SBP, as either a linear or quadratic term, had an adverse effect on functional outcome. In addition, three SBP trajectories were observed, and the high-to-low group was independently associated with functional dependence. Taken together, higher SBP within the first 72h after EVT has a time-dependent association with adverse clinical outcomes. Optimal blood pressure management during the first 72h after EVT may be important to improve clinical outcome.

Cost-Effectiveness of Late Endovascular Thrombectomy vs. Best Medical Management in a Clinical Trial Setting and Real-World Setting.

To assess cost-effectiveness of late time-window endovascular treatment (EVT) in a clinical trial setting and a "real-world" setting. Data are from the randomized ESCAPE trial and a prospective cohort study (ESCAPE-LATE). Anterior circulation large vessel occlusion patients presenting > 6 hours from last-known-well were included, whereby collateral status was an inclusion criterion for ESCAPE but not ESCAPE-LATE. A Markov state transition model was built to estimate lifetime costs and quality-adjusted life-years (QALYs) for EVT in addition to best medical care vs. best medical care only in a clinical trial setting (comparing ESCAPE-EVT to ESCAPE control arm patients) and a "real-world" setting (comparing ESCAPE-LATE to ESCAPE control arm patients). We performed an unadjusted analysis, using 90-day modified Rankin Scale(mRS) scores as model input and analysis adjusted for baseline factors. Acceptability of EVT was calculated using upper/lower willingness-to-pay thresholds of 100,000 USD/50,000 USD/QALY. Two-hundred and forty-nine patients were included (ESCAPE-LATE:n = 200, ESCAPE EVT-arm:n = 29, ESCAPE control-arm:n = 20). Late EVT in addition to best medical care was cost effective in the unadjusted analysis both in the clinical trial and real-world setting, with acceptability 96.6%-99.0%. After adjusting for differences in baseline variables between the groups, late EVT was marginally cost effective in the clinical trial setting (acceptability:49.9%-61.6%), but not the "real-world" setting (acceptability:32.9%-42.6%). EVT for LVO-patients presenting beyond 6 hours was cost effective in the clinical trial setting and "real-world" setting, although this was largely related to baseline patient differences favoring the "real-world" EVT group. After adjusting for these, EVT benefit was reduced in the trial setting, and absent in the real-world setting.

Abstract TMP50: Deep Learning for Hyperdense Middle Cerebral Artery Detection Using High Resolution CT

Introduction: While CT angiography (CTA) remains the gold-standard for non-invasive diagnosis of large-vessel occlusion (LVO), accurate identification of potential thrombectomy patients on non-contrast CT (NCCT) has many practical workflow benefits. However, current evidence suggests that the hyperdense MCA sign on NCCT is an insensitive marker of LVO. In this study, we hypothesize that high-resolution NCCT (HR-NCCT) greatly increases the sensitivity of the hyperdense MCA sign and that a deep learning model can successfully identify the majority of LVO patients on HR-NCCT. Methods: A retrospective cohort of LVO and non-LVO patients with HR-NCCT (0.5-1.0 mm slice thickness) and CTA imaging was identified. For each patient, the location of a hyperdense MCA was annotated by an expert board-certified neuroradiologist after cross-referencing both HR-NCCT and CTA data. A convolutional neural network (CNN) was developed for localization of hyperdense MCA from HR-NCCT imaging only. In brief, the CNN is a 3D contracting-expanding network (18 layers; 596,364 trainable parameters) optimized with deep supervision and class weights. All model statistics are reported after aggregating results from a five-fold cross-validation. Results: A total of 97 LVO-positive and 110 LVO-negative cases were identified. Of the LVO cases, 81.4% (79/97) contained a hyperdense MCA upon expert review. Using these 79 positive (visible dense MCA) and 110 negative cases for training, the model demonstrated an overall 90.0% accuracy in hyperdense MCA detection (92.9% sensitivity, 88.2% specificity). Overall sensitivity was similar for M1 (91.7%) and M2-M3 (94.7%) occlusions. Additionally, of the 18 LVO cases labeled without a hyperdense MCA by expert review, 5 cases were identified correctly by the model and visually confirmed to match occlusion location on CTA. Conclusion: A deep learning model can identify 80.4% of all CTA-confirmed LVO patients using only HR-NCCT, with sensitivity approaching human experts. Combined with ASPECTS evaluation, NCCT-based imaging triage alone may be sufficient to identify the majority of candidate thrombectomy patients.

Abstract TP206: Transcranial Doppler Markers of Increased Microvascular Resistance After Successful Endovascular Revascularization Are Associated With Larger Infarct Volumes

Background: Markers of increased microvascular resistance on Transcranial Doppler (TCD) obtained shortly after successful endovascular therapy (EVT) in patients with large-vessel occlusion (LVO) stroke have been associated with unfavorable outcomes. We aim to investigate whether post-EVT pulsatility index (PI) correlates with final infarct volume in this population. Methods: We analyzed consecutive anterior circulation LVO patients who underwent successful EVT (mTICI 2c-3) from 2012 to 2022. Patients with available TCD within 48 hours of EVT and brain MRI during admission were included. The TCD-derived PI was obtained from the ipsilateral middle cerebral artery. The ABC/2 method was used to estimate the final infarct volume in mL on MRI diffusion-weighted imaging. Pearson correlation and adjusted linear regression analysis were used to investigate the relationship between post-EVT PI and final infarct volume. Linear regression analysis was adjusted for age, NIHSS, and ASPECTS. Results: Out of 155 LVO patients with successful EVT during the study period, 40 were included in the analysis (mean age, 69 ± 16.7 years; 57% female; median NIHSS 15 (IQR 10); and median ASPECTS 9 (IQR, 2)). The median time from EVT to TCD and EVT to MRI was 21 hours (IQR, 17 hours) and 41 hours (IQR, 33 hours), respectively. Post EVT PI displayed a positive moderate correlation with final infarct volume (r=0.39, p&lt;0.01; Figure 1). Larger PI values were independently associated with larger infarct volumes (β = 42.2 mL, 95% CI 37.0 - 47.5 mL). Conclusion: TCD-derived PI shortly after EVT correlated with final infarct volume in successfully revascularized LVO patients. TCD may serve as a valuable tool to identify those at risk for infarct progression and reveal potential therapeutic targets to maximize EVT benefit in this population.

Abstract 44: Portable Optical Blood Flow Monitor for the Detection of Large Vessel Occlusion

Introduction: Early detection of large vessel occlusion (LVO) facilitates triage to appropriate stroke centers and reduces treatment times. Prehospital stroke scales are insensitive, so we investigated the ability of the Openwater Headset, a portable optical blood flow monitor, to detect LVO in patients undergoing acute stroke evaluation. Hypothesis: We hypothesized that the Openwater Headset would detect LVO with greater sensitivity and specificity than prehospital scales. Methods: At two comprehensive stroke centers, eligible patients presented to the emergency department or were transferred from another facility for acute stroke evaluation within 24 hours of symptom onset and NIHSS ≥2. Eligible patients underwent emergent vascular imaging as per routine care. LVO was defined as occlusion of the ICA or the first/second segment of the MCA. Each patient underwent a 70-second bedside optical blood flow evaluation with the Openwater Headset (prior to endovascular therapy, if applicable). The Openwater Headset generated blood flow waveforms based on the relative change in the speckle contrast, acquired at 40 Hz. A deep neural network was trained to identify waveform features that discriminate LVO status ( Figure 1a ), withholding a validation set to test model performance. ROC analysis compared Openwater Headset performance with that of prehospital stroke scales. Results: 135 patients completed the optical evaluation a median of 6 hours after symptom onset (IQR: 3-14). The median NIHSS was 9 (IQR: 4-18). 52 patients (39%) had a LVO. The Openwater LVO stroke alert algorithm had 81% sensitivity and 80% specificity for the presence of LVO (AUC 0.85 by ROC analysis), exceeding that of prehospital stroke scales ( Figure 1b ). Conclusions: The Openwater Headset outperformed prehospital stoke scales for LVO detection in patients who underwent acute stroke evaluation, but further investigation is needed to assess performance in pre-hospital settings.

Sex Differences in Prehospital Identification of Large Vessel Occlusion in Patients With Suspected Stroke.

Differences in clinical presentation of acute ischemic stroke between men and women may affect prehospital identification of anterior circulation large vessel occlusion (aLVO). We assessed sex differences in diagnostic performance of 8 prehospital scales to detect aLVO. We analyzed pooled individual patient data from 2 prospective cohort studies (LPSS [Leiden Prehospital Stroke Study] and PRESTO [Prehospital Triage of Patients With Suspected Stroke Study]) conducted in the Netherlands between 2018 and 2019, including consecutive patients ≥18 years suspected of acute stroke who presented within 6 hours after symptom onset. Ambulance paramedics assessed clinical items from 8 prehospital aLVO detection scales: Los Angeles Motor Scale, Rapid Arterial Occlusion Evaluation, Cincinnati Stroke Triage Assessment Tool, Cincinnati Prehospital Stroke Scale, Prehospital Acute Stroke Severity, gaze-face-arm-speech-time, Conveniently Grasped Field Assessment Stroke Triage, and Face-Arm-Speech-Time Plus Severe Arm or Leg Motor Deficit. We assessed the diagnostic performance of these scales for identifying aLVO at prespecified cut points for men and women. Of 2358 patients with suspected stroke (median age, 73 years; 47% women), 231 (10%) had aLVO (100/1114 [9%] women and 131/1244 [11%] men). The area under the curve of the scales ranged from 0.70 (95% CI, 0.65-0.75) to 0.77 (95% CI, 0.73-0.82) in women versus 0.69 (95% CI, 0.64-0.73) to 0.75 (95% CI, 0.71-0.79) in men. Positive predictive values ranged from 0.23 (95% CI, 0.20-0.27) to 0.29 (95% CI, 0.26-0.31) in women versus 0.29 (95% CI, 0.24-0.33) to 0.37 (95% CI, 0.32-0.43) in men. Negative predictive values were similar (0.95 [95% CI, 0.94-0.96] to 0.98 [95% CI, 0.97-0.98] in women versus 0.94 [95% CI, 0.93-0.95] to 0.96 [95% CI, 0.94-0.97] in men). Sensitivity of the scales was slightly higher in women than in men (0.53 [95% CI, 0.43-0.63] to 0.76 [95% CI, 0.68-0.84] versus 0.49 [95% CI, 0.40-0.57] to 0.63 [95% CI, 0.55-0.73]), whereas specificity was lower (0.79 [95% CI, 0.76-0.81] to 0.87 [95% CI, 0.84-0.89] versus 0.82 [95% CI, 0.79-0.84] to 0.90 [95% CI, 0.88-0.91]). Rapid arterial occlusion evaluation showed the highest positive predictive values in both sexes (0.29 in women and 0.37 in men), reflecting the different event rates. aLVO scales show similar diagnostic performance in both sexes. The rapid arterial occlusion evaluation scale may help optimize prehospital transport decision-making in men as well as in women with suspected stroke.

Abstract 86: Outcomes of Endovascular Therapy for Late Large Vessel Occlusion in Patients With Pre-Stroke Disability

Background: There is a paucity of research to develop evidence-based recommendations for endovascular management in the extended time window (&gt;6 hours after time last seen well [TLSW]) for large vessel occlusion (LVO) patients with pre-stroke disability. Methods: We analyzed data from a multinational cohort (66 sites, 10 countries from 2014 to 2022) of acute ischemic stroke patients with pre-stroke modified Rankin Scale (mRS) 0-4 and anterior or posterior circulation LVO who received endovascular therapy 6-24 hours after TLSW. The primary outcome was the composite of functional independence (FI, mRS 0-2) or return to pre-stroke mRS (return of Rankin, RoR) at 90 days. Outcomes were compared between patients with pre-stroke disability (pre-stroke mRS 2-4) vs those without (mRS 0-1). Results: There were 2231 patients (median age 77 years; median NIH Stroke Scale 16) included in the present study, of whom 564 (25.3%) had pre-stroke disability. The primary outcome (FI or ROR) was seen in 30.7% of patients with pre-stroke disability (FI, 16.5%; RoR 30.7%), compared with 44.1% of those without (FI, 44.1%; RoR 13.0%) ( P &lt;0.0001, Figure 1 ). In both multivariable logistic regression and inverse probability of treatment weighting analysis, pre-stroke disability was not associated with a lower odds of achieving FI or RoR (adjusted odds ratio [aOR] 0.76, 95% confidence interval [CI] 0.50-1.15 and aOR 0.73, 95% CI 0.43-1.25, respectively). FI or ROR was achieved at a higher percentage with reperfusion with mTICI ≥2b than with mTICI 0-2a, both in patients with pre-stroke disability (34.8% vs 10.8%, P &lt;0.0001) and in those without (49.2% vs 12.1%, P &lt;0.0001). Symptomatic intracranial hemorrhage occurred in 6.3% in both groups ( P =0.995). Conclusions: A substantial proportion of late LVO patients with pre-stroke disability regained pre-stroke mRS after EVT and did not have a worse functional prognosis than patients without pre-stroke disability when their pre-stroke mRS was considered.

Abstract TMP47: Identifying and Categorizing Delays to Endovascular Treatment in Patients With Large Vessel Occlusions

Introduction: Early endovascular treatment (EVT) in patients with large vessel occlusions (LVO) is associated with better outcomes. Identifying and categorizing delays to EVT may reveal areas for improvement. Methods: We prospectively identified all patients who underwent EVT at our hospital between May 2022 - 2023. We determined eight steps in acute care: arrival, imaging, IR activation, ED release, arrival to IR, groin puncture, first pass, and recanalization. We classified patients as delayed if any interval exceeded their rolling six-month median. We created 12 categories and 36 subcategories of delays. We used t-test and odds ratios to compare intervals and outcomes between delayed and non-delayed patients. We analyzed subgroups based on causes of delay and location of presentation. Results: Out of 183 LVO patients who underwent EVT, 111 (61%) were delayed. There were no significant differences in age, gender, last known normal to arrival, NIHSS, thrombolytic use, or TICI scale. The delayed group had higher door to groin (99 min), door to device (126 min), and door to recanalization (159 min) compared to the non-delayed group (40, 65, 81 min; p &lt; 0.001). The most common causes of delay were: general case complexity (20%), which was associated with higher door to imaging (59 min, p &lt; 0.001) and imaging to IR activation (37 min, p = 0.03); after hours presentation (19%), which was associated with higher door to imaging (53 min, p = 0.02) and imaging to IR activation (36 min, p = 0.01); and procedural complexity (18%) which was associated with higher groin to device (34 min, p &lt; 0.001) and device to recanalization (53 min, p &lt; 0.001) when compared to other causes of delay. Between the delayed and non-delayed group, there was no significant difference in the length of stay, change in NIHSS at discharge, in-hospital mortality, disposition, or 90-day mRS. Subgroup analysis showed a trend towards higher mortality in delayed patients who presented after hours (OR 3.60 (CI) 0.92-14.10) or in-hospital (OR 2.41 (CI) 0.57-10.19). Conclusions: We determined seven intervals where delays can occur between arrival and recanalization of LVO patients. We created a system for categorizing delays that showed areas for improvement including after hours and in-hospital stroke evaluation.

Abstract WMP66: Detecting Medium Vessel Occlusions and Collateral Assessment With Multimodality AI Approach

Introduction: Recent advances and the use of Artificial intelligence (AI) is changing the standards of care in stroke patients. AI software has a high sensitivity and specificity for identifying Large Vessel Occlusions (LVOs), but the accuracy for detecting Medium Vessel Occlusions (MeVOs) is limited. We investigated the performance of the combination of two different AI modules for the identification of MeVOs. Methods: 150 patients with MeVOs were identified on CTA, using CTP to help localize the lesions, from retrospective databases at the MUSC, Stanford, and Royal Melbourne. Additionally, 55 patients with LVOs on CTA were included. A neuroradiologist confirmed the occluded vessel on CTA for each patient. LVOs were defined as occlusions of the intracranial ICA or horizontal segment of the M1. MeVOs were defined at M2, M3, ACA (A2/A3), or PCA (P2/P3) occlusions. All cases were processed through Rapid LVO, the Rapid Vessel Density module (which assesses hemispheric differences in blood vessel density), and Rapid CTP (Ischemaview Inc., Menlo Park, CA), [AZ1] using automated hypoperfusion intensity ratio (HIR) on CT perfusion (CTP), which estimates collateral flow, differed in LVOs vs. MeVOs. Results: Rapid LVO alone identified occlusions in 41/150 (27.3%) of MeVO patients. Rapid Vessel Density maps identified an additional 38/150 (25.3%) patients with either a 20-25% vessel density reduction or 26-40% reduction. Together, these two modules identified 79/150 (52.6%) of MeVO patients. 54/55 (98.1%) of the LVOs were detected by the Rapid LVO module. The mean HIR was lower in MeVO vs. LVO patients (0.25 vs. 0.45, P-value &lt; 0.001). Patients with M1 or ICA occlusions (LVOs) had average HIRs of 0.46 and 0.47 respectively. Patients with M2, M3, ACA, or PCA occlusions (MeVOs) had average HIRs of 0.30, 0.14, 0.22, and 0.20 respectively. Conclusion: MeVos detection was almost doubled with the use of the RapidAI Vessel Density in conjunction with the LVO module.

Abstract WP140: Perfusion Collateral Index Predicts Infarct Growth in Successfully Reperfused Patients With Acute Ischemic Stroke

Introduction: Robust collaterals are associated with lower rates of infarct growth and improved clinical outcomes in patients with acute ischemic stroke. Perfusion Collateral Index (PCI) and Hypoperfusion Intensity Ratio (HIR) have been shown to correlate with angiographic collaterals. We aimed to assess and compare the ability of PCI and HIR to predict infarct growth in anterior circulation large vessel occlusion (AC LVO) patients who underwent successful reperfusion. Methods: In this retrospective study, AC LVO stroke patients were included if they had pretreatment perfusion (CT or MR), successful reperfusion (mTICI &gt; 2b), and follow up MRI within 24 hours from treatment. HIR (defined as volume of Tmax &gt;10 sec/volume of Tmax &gt;6 sec) was calculated by RAPID software (Version 5.0.4). PCI (defined as volume of delay 2-6 seconds x rCBV) was calculated using Olea software (SP.23). Infarct growth was calculated by subtracting baseline ischemic core (ADC &lt;620 х 10 –6 mm2/s on MRI or rCBF &lt;30% on CTP) from post-treatment MRI volume of DWI hyperintensity. Results: A total of 80 patients were included; 46 female, age (mean + SD): 70.2 + 13.1 years, NIHSS (median, IQR): 14, 8-19, and time from stroke-onset to reperfusion (mean + SD): 389 + 236 minutes. The infarct growth volume was 27 + 52 mL (mean + SD); 47 patients (58.7%) had infarct growth &gt; 10 mL. ROC analysis for prediction of infarct growth &gt; 10 mL revealed AUC/sensitivity/specificity of 0.70/55.3/84.8 for PCI at threshold &lt;60, which was significantly higher (P=0.006) than HIR at threshold of &gt;0.4 (0.50/74.5/24.2) (Figure). Multivariate logistic regression showed PCI (p=0.004) and time-to treatment (p=0.024) were the only independent variables to predict infarct growth. Conclusion: In conclusion, in patients with AC LVO stroke, poor baseline collateral perfusion defined by PCI &lt;60 predicts infarction growth &gt; 10 mL despite successful reperfusion. PCI was superior to HIR in the prediction of infarct growth.

Abstract TP81: Retrospective Gender Disparity Study Evaluating Arterial Size and Post Stroke Outcomes

Introduction: Mechanical thrombectomy is now the standard of care for eligible large vessel occlusion (LVO) patients, but women are less likely to be independent at 90-days and have worse functional outcomes compared to men (Modified Rankin Scale (mRS) &gt; 2). The factors that contribute to this disparity, including arterial size, have not been thoroughly explored and these factors are critical to understand for developing new thrombectomy technologies and techniques. Methods: Retrospective data from Barrow Neurological Institute was analyzed to determine the correlation between arterial diameters and the clinical outcome at 90-days of six patient groups (males vs. females: ages 18-40, 41-65, and 65+) after mechanical thrombectomy. Patients were adults who underwent aspiration thrombectomy for LVO within the past 3 years (verified with documented and calibrated computerized tomography (CT) and angiography) and had a documented 90-day mRS score. Vessel diameters were measured from calibrated patient CT scans and conventional angiograms. After adjusting for critical factors (such as demographics, pre-stroke mRS, and use of rTPA), a multiple logistic regression analysis was implemented to determine the correlation between arterial diameter and the 90-day clinical outcome. Results: The data suggests a correlation between arterial diameters and the efficacy of currently available thrombectomy systems. With cerebral vessel anatomical diameters documented as statistically smaller in women versus men, these results play a role in the worse outcomes seen in women. Conclusion: Currently available mechanical thrombectomy systems may not be optimized for patients with smaller arterial sizes as compared to patients with larger arterial sizes. Future devices with improved navigation and patient-specific size-adaptive capabilities may lead to improved patient outcomes.

Abstract TMP13: Prehospital Stroke Scales Are Non-Inferior to NIHSS in Prediction of Intravenous Thrombolysis Use in a Large Telestroke Network

Introduction: Recent studies report similar outcomes with antiplatelet drugs and intravenous thrombolysis (IVT) in patients with minor nondisabling ischemic stroke. These patients still meet emergent triage criteria and can increase the burden on stroke systems through prehospital stroke activation. Prehospital large vessel occlusion (LVO) scales can improve triage of LVO patients but have not been evaluated as tools to predict IVT administration. We sought to determine if common LVO scales can predict IVT use in a large academic telestroke practice. Methods: This retrospective study included all video telestroke consults performed in a large academic telestroke network from 2019-2020. Patients were excluded if they were on anticoagulation, presented beyond 4.5 hours from last known well, or family declined IVT due to goals of care. We recorded presenting NIHSS and IVT recommendations. NIHSS was used to calculate 7 LVO scales (RACE, G-FAST, FAST-ED, VAN, PASS, 3I-SS, and C-STAT). Scale performance was assessed by calculating area under curve (AUC) and compared to NIHSS total score using the DeLong test. Youden cutpoint was established for each scale and subsequently used to calculate sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), and accuracy. Results: A total of 513 patients were included; 205/513 (40%) were recommended IVT. Median (IQR) NIHSS was 1 (0-3) in non-IVT patients and 6 (4-11) in IVT patients. The RACE and G-FAST scales were noninferior to the NIHSS in predicting IVT recommendation (Table 1). Conclusion: The RACE and G-FAST scales may be useful triage tools to identify patients needing emergent stroke evaluation for consideration of IVT.

Abstract TP195: Impact of Intracranial Atherosclerotic Disease on Thrombectomy Outcomes in Acute Cerebral Infarction With Large Vessel Occlusion

Introduction: In acute cerebral infarction with Large Vessel Occlusion (LVO), Intracranial Atherosclerotic Disease (ICAD) often causes vascular occlusion. Previous studies have noted that ICAD-related LVOs, compared to embolic occlusions, have longer procedural times and lower successful reperfusion rates. However, clinical outcomes remain similar. This study compares post-thrombectomy outcomes in both groups, matched by initial NIHSS scores. Method: From October 2017 to March 2023, we studied LVO cases undergoing thrombectomy for acute ischemic stroke. Our primary focus was on evaluating thrombectomy outcomes within two distinct groups— ICAD-related LVO group (ICAD group) and Embolic LVO group (Embolic group)—matched based on preoperative NIHSS scores. ICAD group was defined as persistent occlusion or residual stenosis at the initial occlusion site. Patient outcomes at 3 months were assessed using modified Rankin Scale (mRS) scores, defining devastating outcomes as mRS 5-6. Successful recanalization was defined as Thrombolysis in Cerebral Ischemia score ≥2b. Logistic regression identified factors independently associated with devastating outcomes. Result: Analyzing 2407 cases, we extracted matched pairs (33 each) adjusted by NIHSS. ICAD group had lower atrial fibrillation frequency, lower BNP levels, more M1 occlusions, and fewer M2 occlusions compared to the Embolic group. In treatment outcomes, ICAD group had lower successful recanalization (82% vs 43%, P =0.001), higher reocclusion rates (0% vs 21%, P =0.005), and longer puncture-to-reperfusion time (median 51 vs 88 minutes, P &lt;0.001). Devastating outcomes were higher in ICAD group (15% vs 39%, P =0.027). Multivariate analysis showed ICAD's independent association with devastating outcomes (Odds ratio, 6.54; 95% CI, 1.56-27.4; P =0.010) along with age, NIHSS, and tPA absence. Conclusion: In thrombectomy-treated LVO patients, matching based on admission NIHSS scores revealed significantly higher devastating outcomes in the ICAD group when compared to the Embolic group.