Patient Selection For Endovascular Therapy Research Articles

Abstract WP143: Use Of CTP For Evaluation Of EVT Candidates In The Early Time Window (<6 Hours From Lkwt) Does Not Delay EVT T And Use Of CTP Beyond 6 Hours Improves Speed Of EVT

Introduction: Computerized Tomography Perfusion (CTP) improves detection of distal occlusion and aids in patient selection for endovascular therapy (EVT) for acute ischemic stroke (AIS). As EVT continues to evolve, it is important to assess if CTP continues to aid in the evaluation of AIS or if it adds unnecessary time. Here we assess whether the imaging approach used to evaluate EVT patients was associated with improved door to device times or clinical outcomes. Specifically, we assessed whether CTA alone vs CTA/CTP combined had an effect on door to device (DTD) for EVT, discharge disposition and 90-day mRS. Methods: Data from 1357 AIS EVT patients from 17 hospitals was obtained from a multi-state health system’s stroke registry between Jan 1, 2018, to Apr 11, 2022. Multivariable mixed-effect linear and logistic regression models were employed to identify the association of evaluation type with DTD, discharge disposition and mRS, adjusting for age, sex, race, mode of arrival, NIHSS, stroke mechanism, medical history, and TICI score. Multivariable ordinal regression model was used with mRS as ordinal variable. Each clinical outcome was assessed for last known well (LKW) to arrival below 6 hours and between 6 and 24 hours. Results: The median age was 74 years, 729 (47.7%) were male; 958 (70.6%) arrived in less than 6 hours from LKW and 399 (29.4%) in the interval between 6 and 24 hours. CTA and CTP evaluation was used for 829 (61.1%) patients. In the multivariable models, evaluation with both CTA and CTP was significantly associated with a decrease of the DTD when LKW to arrival was > 6 hours (n= 955, regression coefficient -16, 95% CI -27, -3.6, p = .01) and had no effect on DTD inside of 6 hours. No significant association was found between evaluation type and discharge disposition or 90-day mRs after adjustment for covariates. Conclusions: In EVT patients presenting inside of 6 hours, addition of CTP to CTA caused no delay in DTD and in those presenting from 6-24 hours adding CTP shortened DTD by 16 minutes. This may reflect that CTP allows for more confident and expeditious treatment. These results along with no effect of evaluation type on clinical outcome argue that there is no disadvantage to the use of CTP inside of 6 hours and a clear time advantage beyond 6 hours.

Diagnostic accuracy of using Alberta Stroke Program Early Computed Tomography Score on CT perfusion map to predict a target mismatch in patients with acute ischemic stroke.

To assess the diagnostic accuracy of using Alberta Stroke Program Early Computed Tomography Score (ASPECTS) on CT perfusion (CTP) map to predict a volumetric target mismatch in patients with acute ischemic stroke (AIS). Three-hundred and seven AIS patients with an onset time within 24h or unclear onset time who underwent CTP evaluation for large vessel occlusion of anterior circulation were enrolled. CTP ASPECTS was evaluated on cerebral blood flow (CBF) and time-to-maximum (Tmax) colored maps, respectively. Automated perfusion analysis software was used to calculate the volumes of ischemic core (volumeCBF<30%) and tissue at risk (volumeTmax>6s). Target mismatch was defined as volumeCBF< 30%<70ml, volumemismatch≥15ml, and volumeTmax >6s/volume CBF< 30%≥1.8. Spearman correlation and receiver operating characteristic curves were used for statistical analyses. Strong correlations were found between CBF ASPECTS and volumeCBF<30%, and between Tmax ASPECTS and volumeTmax>6s for overall population (ρ=-0.872, -0.757) and late-arriving patients (ρ=-0.900, -0.789). Mismatch ASPECTS moderately correlated with mismatch volume for overall population (ρ=0.498) and late-arriving patients (ρ=0.407). A CBF ASPECTS≥5 optimally predicted an ischemic core volume<70ml in overall population (sensitivity, 94.4%; specificity, 80.4%) and late-arriving patients (sensitivity, 89.5%; specificity, 90.5%). A CBF ASPECTS≥6 combined with a Mismatch ASPECTS≥1 optimally identified a target mismatch in overall population (sensitivity, 84.5%; specificity, 77.0%) and late-arriving patients (sensitivity, 83.7%; specificity, 90.0%). CTP ASPECTS might be useful in predicting target mismatch derived from automated perfusion analysis software, and assisting in patient selection for endovascular therapy.

Overview of Imaging Modalities in Stroke.

This article reviews common imaging modalities used in diagnosis and management of acute stroke. Each modality is discussed individually and clinical scenarios are presented to demonstrate how to apply these modalities in decision-making. Advances in neuroimaging provide unprecedented accuracy in determining tissue viability as well as tissue fate in acute stroke. In addition, advances in machine learning have led to the creation of decision support tools to improve the interpretability of these studies. Noncontrast head computed tomography (CT) remains the most commonly used initial imaging tool to evaluate stroke. Its exquisite sensitivity for hemorrhage, rapid acquisition, and widespread availability make it the ideal first study. CT angiography (CTA), the most common follow-up study after noncontrast head CT, is used primarily to identify intracranial large vessel occlusions and cervical carotid or vertebral artery disease. CTA is highly sensitive and can improve accuracy of patient selection for endovascular therapy through delineations of ischemic core. CT perfusion is widely used in endovascular therapy trials and benefits from multiple commercially available machine-learning packages that perform automated postprocessing and interpretation. Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) can provide valuable insights for outcomes prognostication as well as stroke etiology. Optical coherence tomography (OCT), positron emission tomography (PET), single-photon emission computerized tomography (SPECT) offer similar insights. In the clinical scenarios presented, we demonstrate how multimodal imaging approaches can be tailored to gain mechanistic insights for a range of cerebrovascular pathologies.

Abstract TMP64: CT Perfusion Imaging in Telestroke Can Assist With Decision Making Without Delaying IV Alteplase

Introduction: Perfusion based imaging aids in patient selection for endovascular therapy (EVT). Appropriate selection of patients for EVT is an important component of telestroke programs. Thus, telestroke sites could be ideal locations for perfusion imaging. Despite the advantages of perfusion imaging, there is the concern that advanced imaging may delay door to needle time (DTN). We implemented CT perfusion (CTP) using RAPID software at three large primary stroke centers within our telestroke network in December 2017. We aimed to evaluate the proportion of transfers for EVT, door in door out time (DIO) and DTN at telestroke sites before and after CTP implementation. Methods: Data was prospectively collected and retrospectively analyzed as part of our telestroke quality database. We compared data for one year before and one year after implementing CTP at the telestroke sites. We hypothesized that the addition of CTP would not delay DTN. Additionally we hypothesized that a greater proportion of transfers for possible EVT would receive a stroke thrombectomy and that DIO would be reduced after utilizing CTP. Results: Five hundred and forty patients were evaluated via telestroke and completed CT head and/or CT angiography head and neck imaging prior to CTP implementation. Seven hundred and thirteen telestroke patients received CT head, CTA head and neck and CTP imaging after CTP implementation. Of the 1253 patients, 101 (8.1%) were transferred for a possible EVT. Patients receiving CTP had a significantly shorter DIO time (median 109 minutes) compared to patients without CTP (median 122 minutes), U = 425, p = 0.04, r = 0.26. There was no difference in DTN in the 63 IV alteplase treated patients without CTP (median 66 minutes) and 58 IV alteplase treated patients who received CTP (median 63 minutes), U = 1672, p = 0.42, r = 0.07. There was no significant difference in the proportion of patients transferred for a possible EVT that received a stroke thrombectomy in the patients without CTP 28 (74%) compared to patients with CTP 38 (84%), p = 0.23. Conclusions: In conclusion, automated perfusion maps and calculated ischemic penumbra size in CTP allowed telestroke physicians to make quicker transfer decisions, without delaying DTN.

The role of ASPECTs in patient selection for endovascular therapy – CTA source images versus noncontrast CT

The Alberta Stroke Program Early Computed Tomography Score (ASPECTs) on noncontrast CT (NCCT) is widely used for the decision of endovascular therapy (ET) in randomized controlled trials. CT angiography source images (CTA-SI) is another method to evaluate ischemic brain damage. We aimed to evaluate the association between pretreatment ASPECTs on CTA-SI and post-treatment clinical and radiological outcomes in acute stroke patients treated with ET. The association between both scores along with final infarct and outcome were analyzed. A total of 90 patients with successful recanalization were included in the study. The mean age was 59 ± 11.8. According to the results, CTA-SI ASPECTs was better correlated with final infarct than NCCT ASPECTs (p < 0.001). In univariate analyzes, factors associated with good outcome were age, baseline NIHSS score, and presence of diabetes mellitus (p = 0.001, p = 0.002, p = 0.034, respectively). On the other hand, when an analysis differentiating patients by age was performed, 40 patients below 60 years of age had significantly better outcomes despite having higher baseline NIHSS scores (p = 0.002). Finally, in multivariate analyzes, only age and baseline NIHSS score were found to be independent predictors of good outcome (p = 0.003 for both). In conclusion, CTA-SI ASPECTs in patient selection for ET seems to be more useful than NCCT ASPECTs. However, both scoring modalities were not found to be independent predictors of good outcome. Outcomes are changeable for the younger population who could continue their lives with mild or no deficits despite having a relatively low initial ASPECTs.

Abstract WP69: Computed Tomography Perfusion Imaging in Evaluation of Patients With Acute Stroke is Not Associated With Increased Risk of Acute Kidney Injury

Introduction: Mechanical thrombectomy has become standard of care in acute ischemic stroke with proximal arterial occlusion. For patients 6-24 hours from last known well, computed tomography perfusion (CTP) is now frequently used for assessment of endovascular therapy (EVT) eligibility. CTP requires an increased contrast load compared to computed tomographic angiography (CTA). Hypothesis: In patient assessment for EVT, CTA/CTP is not associated with higher incidence of acute kidney injury (AKI) compared to CTA alone. Methods: We reviewed data from consecutive acute stroke alerts at our institution from January-July 2018, and recorded baseline serum creatinine and creatinine at 24, 48, and 72 hours post-alert. AKI was defined by an increase in serum creatinine of 0.3, or more than a 1.5 fold increase in baseline creatinine, according to the Acute Kidney Injury Network definition. We compared patients receiving CTA/CTP versus CTA alone using independent samples t-test, including variables of age, NIHSS, baseline creatinine, and creatinine at 24, 48, and 72 hours. Chi-square testing was performed to compare incidence of AKI between groups. A binary logistic regression model was performed including covariates of age, sex, location of alert (emergency room or inpatient), NIHSS, baseline creatinine and imaging group. Significance was defined as p &lt; 0.05 for all tests. Results: Analysis included 285 patients: 210 receiving CTA alone, and 75 receiving CTA/CTP. Incidence of AKI was 4.7% in the CTA alone group versus 4% in the CTA/CTP group (χ2=0.74, p=0.786). The two groups did not differ with regard to age, NIHSS, or serum creatinine at any time point. In the binary logistic regression model, addition of CTP to CTA did not increase the odds ratio of developing AKI (OR 1.076 [95% CI 0.276-4.193]; p=0.916). Conclusions: In acute stroke assessment for EVT eligibility, the addition of CTP to CTA did not increase rates of AKI. While this retrospective analysis includes the possibility of selection bias, the two groups were similar in baseline characteristics including kidney function. These results provide Level II, Class B evidence supporting the safety of CTP in patient selection for EVT and may inform future AHA/ASA guidelines for management of acute ischemic stroke.

Abstract WP78: Deep Learning for Acute Ischemic Stroke on Diffusion MRI: Performance Analysis in a Consecutive Cohort

Background: Diffusion-weighted imaging (DWI) is the gold standard for detection of acute ischemic stroke (AIS) and may guide patient selection for endovascular therapy. Machine learning algorithms can enhance clinical workflow in suspected AIS by providing early diagnosis and quantitative imaging biomarkers. We tested the hypothesis that our deep learning algorithm for detection of acute ischemia performs robustly in a real-world environment. Methods: We developed a novel deep neural network architecture (YNet) that operates on MRI diffusion data at full resolution. YNet demonstrated strong performance in AIS detection and segmentation on test and validation datasets. After validation, we challenged YNet to assess 1081 consecutive brain MRIs acquired from 9 different scanners at our institution over a 2-week period. Studies were labeled as having AIS by a radiologist who used the final clinical imaging report. A series selection algorithm was applied to each study to identify DWI and apparent diffusion coefficient (ADC) series for input to the YNet using DICOM metadata to ensure relevant criteria are met (B value = 1000, axial plane, etc.). Patients with known diagnoses were excluded. Results: The series selection algorithm identified 826 studies that had DWI and ADC series with the established criteria. After exclusion of patients with known diagnoses, 378 studies were assessed by the YNet algorithm for the presence of AIS. The prevalence of AIS was 11.9% within this consecutive cohort. The algorithm detected 43 out of the 45 studies with AIS. Sensitivity and specificity for detection were 95.5% and 97.0%, respectively. Conclusion: Our YNet algorithm demonstrated excellent performance in detecting AIS in a serially-acquired dataset. Fully automated implementation will require further refinement of the series selection algorithm.

Abstract WP4: Which Characteristics Determine the Decision to Proceed With Endovascular Therapy in Acute Stroke Patients: Results From an International Multidisciplinary Study

Introduction: The current management of acute ischemic stroke has changed recently with the publication of randomized trials using endovascular therapy (EVT). Rationale/Hypothesis: Limited information is however available on how physicians make decisions regarding patient selection for endovascular therapy (EVT) in the real-world. Methods: We conducted an international web-based cross-sectional survey of stroke physicians and interventionalists to assess the decision to offer EVT. Part 1 of the survey used hierarchical Bayes’ disaggregate discrete choice modelling to analyze ten pairs of patient scenarios, randomly generated from ten key patient characteristics to have respondents choose which scenario was best suited for EVT in their practice. Part 2 of the survey used mixed effects logistic regression modelling to analyze 22 randomly chosen patient scenarios, again randomly generated from several key patient and hospital level characteristics. Results: 607 physicians [mean age of 44 (SD 8.5) years, 83.5% men, 53.6% neurologists, 28.7% neuro-interventionists, 13.3% neurosurgeons, 4.7% other], from 38 countries participated. Using disaggregate discrete choice analysis, the most influential characteristic in deciding about EVT was the extent of ischemic change (ASPECTS)/volume of infarct core (26-28% of the choice). Patient age, premorbid status, baseline NIHSS score, and occlusion location (13-15% each) were the other relevant characteristics. Using mixed effects logistic regression, baseline stroke severity (NIHSS&gt; 15 vs. NIHSS 0-5, OR 6.7; 95% CI 4.8-9.5), ASPECTS (5-7 vs. 0-4, OR 9.4; 95% CI7.4-11.9) and occlusion location (distal M2 vs. ICA/M1, OR 012; 95% CI 0.08-0.17) were the most relevant characteristics in deciding about EVT. Time from stroke onset, sex, comorbidities, time of day (off hours vs. day time) were all less relevant in deciding about EVT in both analyses. Conclusion: Severity of stroke assessed clinically, and extent of brain infarction and location of thrombus assessed on imaging are the dominant characteristics that treating physicians use in the real world when deciding about EVT for patients with an acute ischemic stroke.

Pittsburgh response to endovascular therapy score as a pre-treatment prognostic tool: External validation in Trevo2.

Background Optimal patient selection is needed to maximize the therapeutic benefit of endovascular therapy for large vessel occlusion stroke. Aims To validate the Pittsburgh response to endovascular therapy (PRE) score in a randomized controlled trial (Trevo2) comparing stent retriever (Trevo) to the Merci device. Methods Trevo2 participants with internal carotid, M1 and M2 middle cerebral artery occlusions with prospectively collected baseline stroke severity (NIHSS), degree of hypodensity (CT ASPECTS), and three-month modified Rankin Scale (mRS) were included. Multivariable regression was used to confirm association between PRE score variables (age, NIHSS, and ASPECTS), medical comorbidities, randomization arm, and reperfusion status (mTICI2B/3) with good outcome (three-month modified Rankin Scale 0-2). Predictive power (area under the receiver operating characteristic curve) for good outcome of pre-treatment prognostic scores (PRE, THRIVE, HIAT2) was compared. Rates of good outcome were compared between successfully reperfused (mTICI2B/3) and non-reperfused (mTICI0-2A) patients across previously identified PRE score risk groups. Results Age, NIHSS, ASPECTS, reperfusion status, and randomization arm were independent predictors of good outcome. PRE score had moderate predictive power (AUC = 0.75) for good outcome and was comparable to other pre-treatment scores. Reperfusion resulted in maximal treatment benefit in patients with PRE score 0-24 (60% vs. 12.5%, p = 0.002) but not in those with PRE ≥50 (11.8% vs. 0.0%, p = 0.49). Conclusion The PRE score is a validated predictor of functional outcome and a tool for patient selection for endovascular therapy in anterior large vessel occlusion stroke. Our finding of limited benefit of reperfusion in patients with PRE score ≥50 needs to be prospectively validated.

Large-Vessel Occlusion Stroke: Effect of Recanalization on Outcome Depends on the National Institutes of Health Stroke Scale Score

Arterial recanalization is currently considered the main standard of successful early management of acute ischemic stroke. Intravenous (IV) thrombolysis with tissue plasminogen activator (tPa) is the only Food and Drug Administration-approved medical treatment. Large-vessel occlusion, estimated to account for up to 40% of all acute ischemic strokes, is often refractory to IV thrombolysis and is associated with a poor patient outcome. Mechanical recanalization procedures are therefore increasingly used in the treatment of large-vessel occlusion refractory to, or presenting outside the accepted time window for, IV thrombolysis. The aim of this study was to investigate the effect of early vessel recanalization on clinical outcome in patients with large-vessel occlusion stroke. This is a single-center cohort study, analyzing prospectively collected data on 152 patients with large-vessel occlusion and acute ischemic stroke. Seventy-one patients received endovascular treatment (of whom 57.7% also received IV tPA), and 81 (55.6% of whom also received IV tPa) were not treated with endovascular therapy. Clinical outcome was compared for 2 cohorts: patients who recanalized (n = 46) and patients with persisting large-vessel occlusion (n = 106). Early recanalization was an independent predictor of a good clinical outcome in only those patients who presented with a severe ischemic stroke (National Institutes of Health Stroke Scale [NIHSS] score >15; P = .017). This was not the case for less severe strokes (NIHSS score ≤ 15) where recanalization did not lead to more patients with functional independence at 90-day follow-up (P = .21). In this study of acute large-vessel occlusion stroke, we found that clinical outcome following early recanalization was dependent on the patient's pretreatment NIHSS score. A non-negligible proportion of patients with milder strokes did well despite persistent large-vessel occlusion. These results may suggest that in patients who are able to maintain adequate collateral flow despite proximal arterial occlusion, effective adaptive mechanisms are present, which for some patients are long-lasting. This may influence the process of appropriate patient selection for endovascular therapy.

Pittsburgh Response to Endovascular therapy (PRE) score: optimizing patient selection for endovascular therapy for large vessel occlusion strokes

BackgroundEndovascular therapy seems to benefit a subset of patients with large vessel occlusion strokes. We aimed to develop a clinically useful tool to identify patients who are likely to benefit...

Low signal, high noise and large uncertainty make CT perfusion unsuitable for acute ischemic stroke patient selection for endovascular therapy

Neurointerventionists are on the cusp of revolutionizing the care of the acute ischemic stroke patient. The stage is set for a major advance after 2 decades of experience and the...

E-044 Impact and outcomes of physiologic imaging for acute stroke patient selection for endovascular therapy

BackgroundThere are more than 700 000 new or recurrent strokes that occur in the USA each year. The majority are due to acute cerebral ischemia. Limited clinical data exist on...