Thrombectomy-capable Stroke Centers Research Articles

Incidence of Acute Ischemic Stroke With Visible Arterial Occlusion: A Population-Based Study (Dijon Stroke Registry).

Because of several methodological limitations, previous studies focusing on the prevalence of large vessel occlusion in ischemic stroke (IS) patients provided conflicting results. We evaluated the incidence of IS with a visible arterial occlusion using a comprehensive population-based registry. Patients with acute IS were prospectively identified among residents of Dijon, France, using a population-based registry (2013-2017). All arterial imaging exams were reviewed to assess arterial occlusion. Annual incidence rates of IS (first-ever and recurrent events) and IS with a visible occlusion were calculated. One thousand sixty cases of IS were recorded (mean age: 76.0±15.8 years, 53.9% women). Information about arterial imaging was available in 971 (91.6%) of them, and only preexisting dementia was independently associated with having missing information (odds ratio=0.34 [95% CI, 0.18-0.65], P=0.001). Among these patients, 284 (29.2%) had a visible arterial occlusion. Occlusion site was the anterior circulation in 226 patients (23.3% of overall patients with available data) and the posterior circulation in 58 patients (6.0%). A proximal occlusion of the anterior circulation was observed in 167 patients (17.2%). The crude annual incidence rate of total IS per 100 000 was 138 (95% CI, 129-146). Corresponding standardized rates were 66 (95% CI, 50-82) to the World Health Organization and 141 (95% CI, 118-164) to the 2013 European populations. The crude annual incidence rate of IS with a visible arterial occlusion per 100 000 was 37 (95% CI, 33-41) and that of IS with a proximal occlusion of the anterior circulation was 22 (95% CI, 18-25). Corresponding standardized rates were 18 (95% CI, 10-26) and 10 (95% CI, 8-13) to the World Health Organization population, and 38 (95% CI, 26-50) and 23 (95% CI, 19-26) to the 2013 European population, respectively. These results will be helpful to plan the need for thrombectomy-capable stroke center resources.

Endovascular Therapy for Patients With Acute Ischemic Stroke During the COVID-19 Pandemic: A Proposed Algorithm.

Endovascular Therapy for Patients With Acute Ischemic Stroke During the COVID-19 Pandemic: A Proposed Algorithm.

Abstract WP287: Modeling the Impact of Pre-Hospital Triage on a True Life Drip and Ship Thrombectomy Patient Cohort

Introduction: Patients with emergent large vessel occlusions (ELVO) are often brought to the closest hospital, possibly given intravenous tPA, and transferred to a hospital capable of performing endovascular intervention. This results in significant delays to thrombectomy and worse patient outcomes when compared with patients brought directly to endovascular centers. In New York City, the pre-hospital system has created a protocol for EMS to use a clinical screening tool to triage stroke patients, and bring those with suspected ELVO directly to comprehensive (CSC) or thrombectomy-capable stroke centers (TSC). Objective: To model the impact of EMS triage protocols on administration of tPA, initiation of endovascular therapy, and recanalization of large vessel occlusions using a real life cohort of thrombectomy patients. Methods: Using our system wide prospectively collected stroke database, we selected a consecutive cohort of 80 thrombectomy patients who were brought by EMS to a primary stroke center then transferred to a TSC or CSC for endovascular intervention. The patient’s initial EMS pickup address was used to calculate the closest TSC or CSC using Google Maps API. Driving time was calculated based on traffic patterns at the time of pickup. Using data from a cohort of 69 consecutive patients that were brought directly to a TSC or CSC by EMS and underwent endovascular intervention, we derived median door to needle and door to groin puncture times. These times, combined with calculated driving distance, were used to model the timing of treatment in the triage model. Timings in the actual cohort versus the model were compared. Results: In the “actual” drip and ship cohort versus our model, first medical contact (FMC) to endovascular center door was 211 versus 32 minutes (p<0.01), first medical contact (FMC) to tPA was 91 versus 81 minutes (p=0.07), FMC to groin puncture was 265 versus 154 minutes (p<0.01), and FMC to TICI2B+ recanalization was 313 versus 205 minutes (p<0.01). Conclusions: Modeled EMS pre-hospital triage of ELVO patients results in a significant decrease in endovascular treatment times without change in tPA times. As triage tools increase in sensitivity and specificity, EMS triage protocols stand to improve patient outcomes.

Abstract 168: Outcomes of Intra-Arterial Tissue Plasminogen Activator Rescue Therapy During Stroke Thrombectomy-Insights From the STAR Collaboration

Introduction: Intra-arterial tissue plasminogen activator (IA-tPA) can be used as rescue therapy during mechanical thrombectomy for stroke patients, mostly in the setting of distal occlusion. The outcomes of IA-tPA has not been assessed in large-scale multi-center studies yet. Methods: We used data from the Stroke Thrombectomy and Aneurysm Registry (STAR), which included prospectively maintained databases of 11 thrombectomy-capable stroke centers in the US, Europe, and Asia. We compared the baseline characteristics, procedural metrics, rate of symptomatic intracranial hemorrhage (sICH), and long-term functional outcomes between thrombectomy patients who received rescue IA-tPA and a control group of thrombectomy patients with matched age, National Institute of Health stroke scale (NIHSS) on presentation, location of occlusion and IV-tPA receipt. Results: A total of 2827 thrombectomy patients were included in the STAR registry. Out of those, 205 patients received IA-tPA. We matched 191 patients from the IA-tPA group with a control group of 191 patients (table 1). No difference was seen in age, sex, race, vascular risk factors, or Alberta Stroke Program Early CT (ASPECT) score between both groups. In addition, procedural metrics, including onset to groin time, the procedure duration, and rate of successful recanalization (modified Thrombolysis in Cerebral Infarction score≥2b) were similar. Finally, similar outcomes were noted in both groups, including the rate of sICH and good 90-day functional outcome (modified Rankin scale≤2). Conclusion: The use of IA-tPA as an adjunctive treatment to mechanical thrombectomy was safe but did not result in a higher rate of successful recanalization or good long-term functional outcomes.

Abstract TMP4: Impact of Bridging Therapy With Intravenous Thrombolysis Prior to Mechanical Thrombectomy in Patients With Large Vessel Occlusion- Insights From the STAR Registry

Introduction: Clinical trials have proven the safety and efficacy of mechanical thrombectomy (MT) with intravenous alteplase (tPA) compared to tPA alone in patients presenting with large vessel occlusion (LVO). The impact of tPA prior to MT on procedural metrics, successful revascularization, symptomatic hemorrhage and long-term functional outcome has not been established from large scale real-world studies. In this study we evaluate the impact of tPA prior to MT on procedural times, immediate and long-term outcomes. Methods: The STAR registry combined prospectively maintained databases of 11 thrombectomy-capable stroke centers in the US, Europe and Asia. Patients who received mechanical thrombectomy with or without intravenous tPA prior to MT were included in these analyses. Baseline characteristics, procedural time, successful revascularization (TICI ≥ 2B), symptomatic intracranial hemorrhage (PH2), and long-term functional outcomes were compared between the two groups. Results: Total of 1869 patients were included in this analysis. Of those, 907 received tPA prior to MT. Baseline features and outcomes are summarized in table 1. There were more white patients in the non-tPA group, and more patients in this group had atrial fibrillation and hyperlipidemia; otherwise there were no differences in baseline features between the two groups. Median NIHSS on admission was 16 in both groups, median ASPECTS was 9 in the tPA group versus 8 in the non-tPA group, p=0.208. Patients in the tPA group had higher rate of successful revascularization, lower number of revascularizations attempts and were more likely to achieve excellent long-term functional outcome. There was no difference in procedural time, rate of symptomatic hemorrhage or length of hospital stay. Conclusion: Bridging therapy with intravenous tPA prior to mechanical thrombectomy may facilitate MT and yield to better long-term functional outcome.

Abstract WMP11: Safety and Efficacy of Mechanical Thrombectomy in Patients With Minor Stroke Due to Large Vessel Occlusion- Insights From the STAR Registry

Introduction: Mechanical thrombectomy (MT) is the current standard of care treatment for patients presenting with severe symptoms due to large vessel occlusion (LVO); approximately 30% of patients with LVO however present with mild symptoms (NIHSS < 6). The safety and efficacy of MT in this group has not yet been established. The purpose of this study is to evaluate the safety of MT in patients presenting with mild symptoms due to LVO in a large multicenter registry. Methods: STAR registry combined the prospectively maintained databases of 11 thrombectomy-capable stroke centers in the US, Europe and Asia. Patients who underwent MT were included in these analyses. Baseline features, risk factors, location of occlusion, time from symptom onset, tPA receipt, procedural complication rates, symptomatic hemorrhage, and long-term functional outcome were compared between patients with mild symptoms (NIHSS < 6) to those with severe symptoms (NIHSS ≥ 6). Results: Total of 2,114 patients were included in this analysis. Of those, 162 patients presented with NIHSS ≥ 6. Baseline features and outcomes are summarized in table 1. There was no difference in age, or sex, tPA receipt, number of attempts, rate of successful revascularization, symptomatic hemorrhage, or length of hospital stay. Median ASPECTS score was 9 in the mild Vs 8 in the severe symptom group (p=< 0.001), there was a higher percentage of patients in the mild symptom group with hypertension, hyperlipidemia, and LVO in the posterior circulation. Conversely there were more patients with atrial fibrillation in the severe symptom group. Excellent outcome (mRS 0-2 at 90 days) was achieved in 69.8% patients in the mild group compared to 38.3% in the severe group, p=<0.001) Conclusion: In patients with minor symptoms due to large vessel occlusion, mechanical thrombectomy appears to be safe with low complication rates. Approximately seventy percent of patients achieved excellent functional recovery. Table 1:

Abstract TP12: The Trend of Successful First Pass in M2 Segment Stroke Thrombectomy- Insights From the STAR Collaboration

Introduction: Stroke thrombectomy devices and the experience of neurointerventionists have improved significantly over the last few years making targeting distal occlusions such as of the M2 segment of the middle cerebral artery more feasible. We aimed to study the trend in the successful first pass (SFP) of M2 occlusions over time using the data from a contemporary multicenter registry. Methods: We reviewed the data from the Stroke Thrombectomy and Aneurysm Registry (STAR), which included data from 11 thrombectomy-capable stroke centers to identify stroke patients who underwent mechanical thrombectomy of M2 segment occlusion. SFP was defined by achieving modified Thrombolysis in Cerebral Infarction (mTICI) score≥2b with a single thrombectomy device pass. We analyzed the linear trendline of the rate of SFP over time. Then, we used a logistic regression model to assess predictors of SFP of M2 segment occlusion. Results: We included 401 patients who underwent stroke thrombectomy of M2 occlusion; median age was 71 (IQR 60-80), 212 (52.9%) were females, 174 (43.4%) were white, National Institute of Health stroke scale (NIHSS) was 14 (IQR 8-19), Alberta Stroke Program Early CT (ASPECT) score on presentation was 9 (IQR 7-10) and onset wot groin time was 287 (IQR 181-454). SFP was achieved in 118 (29.4%) patients (linear trendline over time is in Figure 1). Presenting after 2014 was an independent predictor of SFP (OR 1.9, 95% CI 1.1-3.2, P=0.019) after controlling for age, sex, NIHSS on presentation, intravenous alteplase (IV-tPA), and onset to groin time. Conclusion: SFP rate of M2 segment occlusion has increased after 2014 likely secondary the improvement in stroke thrombectomy devices and neurointerventionists experience.

Abstract WP3: Predictors and Outcomes of Successful First Pass in Neurothrombectomy- Insights From the STAR Collaboration

Introduction: Shorter procedure time during neurothrombectomy is a strong predictor for good outcomes in stroke patients with large vessel occlusion. We sought to assess the predictors and outcomes of successful first pass (SFP) using multi-center investigator-initiated database. Methods: Prospectively collected neurothrombectomy data from 11 thrombectomy-capable stroke centers was combined in the Stroke Thrombectomy and Aneurysm Registry (STAR). SFP was defined by achieving modified Thrombolysis in Cerebral Infarction (mTICI) score≥2b with a single thrombectomy device pass. We compared the baseline characteristics, procedural metrics, rate of symptomatic intracranial hemorrhage (sICH), and long-term functional outcomes between SFP and non-SFP patients. A multivariate logistic regression analysis was used to assess the predictors of SFP and evaluate whether SFP was an independent predictor for good long-term functional outcomes (90-day mRS≤2). Results: A total of 733 SFP patients and 1134 non-SFP patients were included in this analysis. SFP patients were older (73 vs. 70, P=0.001), had higher Alberta Stroke Program Early CT (ASPECT) score on presentation (9 vs. 8, P=0.002). The use of Solumbra technique was an independent predictor of SFP (OR 1.2, 95% CI 1.1-1.4, P=0.004) after controlling for age, sex, location of occlusion, National Institute of Health stroke scale (NIHSS) on presentation, intravenous alteplase (IV-tPA), and onset to groin (OTG) time. SFP was an independent predictor for good long-term functional outcomes (OR1.6, 95% CI 1.1-2.3, P=0.008) after controlling for age, sex, location of occlusion, NIHSS on presentation, OTG time, IV-tPA, procedure technique, and procedure duration. Conclusion: SFP lead to higher rates of functional independence in stroke patients with large vessel occlusion. These records reiterate the importance of SFP as a benchmark measure for stroke thrombectomy devices.

Abstract WP2: Long-Term Functional Outcomes Following Mechanical Thrombectomy Stratified by Race- Insights From the STAR Collaboration

Introduction: Previous research reported higher prevalence of vascular risk factors and worse outcomes after stroke in non-white patients compared to whites. Whether similar results still apply in the post mechanical thrombectomy era remains unknown. Methods: The STAR registry combined the prospectively maintained databases of 11 thrombectomy-capable stroke centers in the US, Europe, and Asia. Consecutive patients who underwent MT were included in these analyses. Baseline features, risk factors, location of occlusion, time from symptom onset, tPA receipt, procedural complication rates, symptomatic hemorrhage, and long-term functional outcome were compared between white and non-white patients. Multivariate logistic regression analysis was performed to evaluate the impact of race on long-term outcome. Results: Total of 2,284 patients were included in this analysis. Of those, 1,436 (62.9%) were white. Baseline features and outcomes are summarized in table 1. Non-white patients were older ( 71 Vs 66, p=<0.001), more likely to be female ( 53.1% Vs 48.5%, p=0.034), had lower NIHSS on admission ( 15 Vs 16, p=<0.001), higher prevalence of hypertension, hyperlipidemia, diabetes, lower incidence of atrial fibrillation, higher rate of tPA receipt, shorter onset to groin access times, and longer procedural times. White patients had higher rates of successful revascularization (77.4% Vs 72.3%, p=0.006) and longer hospital stay. On multivariate logistic regression analysis, white race was an independent predictor of good 90-day outcome (OR 1.35, 95% CI 1.03-1.76, P=0.031) after controlling for age, sex, location of occlusion, IV-tPA, ASPECT score, procedure duration and final TICI score. Conclusion: In this study, white race was independent predictor of good 90-day outcome. This finding could be due to higher prevalence of vascular risk factors in non-white patients.

Outcomes of interfacility helicopter transportation in acute stroke care.

To evaluate the long-term functional outcome of interhospital transfer of patients with stroke with suspected large vessel occlusion (LVO) using Helicopter Emergency Medical Services (HEMS). Records of consecutive patients evaluated through 2 telestroke networks and transferred to thrombectomy-capable stroke centers between March 2017 and March 2018 were reviewed. Inverse probability of treatment weighting (IPTW) using the propensity score was performed to address confounding factors. Multivariate logistic regression analysis with IPTW was used to determine whether HEMS were associated with good long-term functional outcome (modified Rankin scale score ≤ 2). A total of 199 patients were included; median age was 67 years (interquartile range [IQR] 55-79 years), 90 (45.2%) were female, 120 (60.3%) were white, and 100 (50.3%) were transferred by HEMS. No significant differences between the 2 groups were found in mean age, sex, race, IV tissue plasminogen activator (tPA) receipt, and thrombectomy receipt. The median baseline NIH Stroke Scale score was 14 (IQR 9-18) in the helicopter group vs 11 (IQR 6-18) for patients transferred by ground (p = 0.039). The median transportation time was 60 minutes (IQR 49-70 minutes) by HEMS and 84 minutes (IQR 25-102 minutes) by ground (p < 0.001). After weighting baseline characteristics, the use of HEMS was associated with higher odds of good long-term outcome (OR 4.738, 95% CI 2.15-10.444, p < 0.001) controlling for transportation time, door-in-door-out time, and thrombectomy and tPA receipt. The magnitude of the HEMS effect was larger in thrombectomy patients who had successful recanalization (OR 1.758, 95% CI 1.178-2.512, p = 0.027). HEMS use was associated with better long-term functional outcome in patients with suspected LVO, independently of transportation time.

Initial Emergency Room Triage of Acute Ischemic Stroke.

Early recognition and differentiation of acute ischemic stroke from intracranial hemorrhage and stroke mimics and the identification of large vessel occlusion (LVO) are critical to the appropriate management of stroke patients. In this review, we discuss the current evidence and practices surrounding safe and efficient triage in the emergency room. As the indications of stroke intervention are evolving to further improve stroke care, focus has begun to revolve around recognition of LVO and provision of endovascular thrombectomy with or without the administration of tissue plasminogen activator. Systems of stroke care are being organized to achieve this goal without delay. Clinical history is important in determining time of onset or last known well time, but, alone or along with an examination, it cannot reliably predict an LVO or exclude intracranial hemorrhage and stroke mimics. The choice of imaging is influenced mainly by the duration of symptoms. On the basis of recent trials, patients presenting after the 6-h therapeutic window can be considered for endovascular thrombectomy if the computed tomographic or magnetic resonance perfusion imaging shows favorable findings. The Society of NeuroInterventional Surgery has established time metrics for each step of triage and initial management. Hospitals are required to develop multidisciplinary stroke teams and emergency protocols to meet these goals. There also needs to be coordination of the emergency medical services with the emergency facility of an appropriate stroke center (a primary stroke center, comprehensive stroke care center, or a thrombectomy-capable stroke center).

The Accuracy of Large Vessel Occlusion Recognition Scales in Telestroke Setting

Introduction: A significant proportion of acute ischemic stroke (AIS) patients who are evaluated through telestroke consultation are transferred to thrombectomy-capable stroke centers (TSCs) for concern of large vessel occlusion (LVO). Patient triage selection is commonly based on the clinical suspicion of LVO, which lacks specificity and could result in unnecessary transfers. In this study, we aimed to assess the accuracy of the most commonly used LVO recognition scales in telestroke setting. Methods: AIS patients transferred to TSCs for suspicion of an LVO were included in this retrospective study. Patients were evaluated by a stroke neurologist through a telestroke consult before transfer. The National Institute of Health Stroke Scale (NIHSS) score documented by the stroke neurologist was retrieved from medical records and used to calculate five other LVO recognition scales (Rapid Arterial Occlusion Evaluation Scale [RACE], Field Assessment Stroke Triage for Emergency Destination [FAST-ED], Cincinnati Prehospital Stroke Severity Scale [CPSSS], 3-item stroke scale [3I-SS], and Prehospital Acute Stroke Severity Scale [PASS]). We calculated the sensitivity, specificity, accuracy, positive and negative predictive values, false positive rate (FPR), and false negative rate (FNR) of each score using published cutoffs and then examined all possible cutoff values for each of these scales in addition to the NIHSS. Results: A total of 439 patients were included in the final analysis. A total of 48.5% of patients had an LVO confirmed on computed tomography angiogram. RACE score had the highest accuracy (78%). Overall, the five derived LVO recognition scores have at least 10% FNR. When examining all possible cutoff values, the NIHSS (cutoff of 6) had a 3% FNR but 73% FPR (false transfer). Conclusion: The use of the NIHSS and other LVO recognition scores over telestroke may result in unnecessary transfers. Better diagnostic tools that could maximize sensitivity with acceptable specificity are urgently needed.

Abstract TP377: Routing for Rapid Results

Background: In 2016, the American Heart Association (AHA) published recommendations for emergent large vessel occlusion (ELVO) routing at the International Stroke Conference based on symptomatology and distance from a thrombectomy capable stroke center. Research has shown that a rapid door to puncture and reperfusion time leads to improved patient outcomes in large vessel occlusion patients who meet criteria for thrombectomy. The door to puncture (D2P) benchmark for the AHA Get with the Guidelines data registry and the local Emergency Medical Services (EMS) is 90 minutes. Purpose: The purpose of the project was to find a way to shorten the D2P time in ELVO patients in a 265 bed community hospital. Method: The solution to shortening the D2P time was to identify ELVO patients using an evidenced based stroke severity scale. Collaboration ensued between the thrombectomy capable stroke centers and local EMS to discuss ELVO routing. Previously, stroke patients were identified by EMS only using the Cincinnati Prehospital Stroke Scale (CPSS). The local EMS and the participating hospitals selected the Ventura ELVO Scale (VES), an evidenced based stroke severity scale, to assess positive CPSS patients in the field. Policies were developed, education was rolled out, and ELVO routing went live in October 2017 with two ELVO receiving centers. Our hospital, one of the receiving centers, collected data to follow the trend of D2P times. Results: D2P median prior to going live with ELVO routing was 127 minutes. Only one patient out of fifteen patients between December 2016 and August 2017 had a D2P less than 90 minutes. Between October 2017 and July 2018, after ELVO routing began, ten out of fourteen patients had D2P less than 90 minutes. The median improved to 89 minutes on these patients. All D2P times were then tabulated together to calculate a total median time of all cases. Conclusion: ELVO routing combined with the implementation of the VES enabled us to be successful in shortening our D2P to below the benchmark of 90 minutes. This method may be beneficial in other community based hospitals and counties looking to shorten their D2P.

Door in door out and transportation times in 2 telestroke networks.

Inter-hospital transfer is important in the treatment of acute stroke. We sought to assess door in to door out (DIDO) time at spoke sites, and transportation time between spoke sites and thrombectomy-capable stroke center (TSC) in 2 large, rural telestroke networks. Records of patients treated with tissue plasminogen activator through 2 telestroke networks between March 2017 and December 2017 were reviewed. Mann-Whitney test was used to compare median times, and a generalized linear regression model was used to predict the total time of care controlling for transportation distance. Eighty-five patients were included with median NIH stroke scale on presentation of 13 (interquartile range [IQR] 7-17), median door to needle time 49 minutes (IQR 40-62), and median DIDO 111 minutes (IQR 92-157). Eighteen patients (21%) underwent computed tomography angiography (CTA) at spoke prior to transportation. Median DIDO was 169 minutes for patients who received CTA before transfer, compared with 107 minutes for patients who did not (p = 0.0004). Median door-to-groin time at TSC was 68 minutes for the CTA group and 85 minutes in the non-CTA group (p = 0.832). Controlling for distance, the predicted time of care from spoke door in time to groin puncture at TSC (sDTG) is 93.68 minutes longer for patients who receive CTA prior to transport (p = 0.034). In the included telestroke networks, the sDTG time is longer when CTA is conducted at spoke site prior to transportation to TSC. New strategies are urgently needed to decrease sDTG when CTA is done prior to transfer to TSC.

Abstract WP119: Leukoaraiosis Attenuates Diagnostic Accuracy of Large Vessel Occlusion Scales

Background and Purpose: Preclinical stroke scales may help identify patients likely to have large vessel occlusion (LVO) to facilitate rapid triage to thrombectomy-capable stroke centers. Scale misclassification may result in inaccurate decisions and possible harm. Pre-existing leukoaraiosis has been shown to attenuate the association between deficit type and stroke severity. We sought to determine whether leukoaraiosis affects the predictive ability of 5 commonly used LVO scales. Materials and Methods: We retrospectively analyzed 274 consecutive stroke patients with available brain MRI and vessel imaging. The following LVO scales were used: 3 Item Stroke Scale (3I/SS), Field Assessment Stroke Triage for Emergency Destination (FAST-ED), Rapid Arterial Occlusion Evaluation (RACE), Vision, Aphasia, Neglect (VAN) score, and Cincinnati Prehospital Stroke Severity Scale (CPSSS). For diagnostic scale accuracy, we assessed sensitivity, specificity, positive predictive value, negative predictive value, and kappa. Multivariable logistic regression was used to determine the scales’ predictive ability after adjustment for leukoaraiosis and potential confounders. Results: In unadjusted analyses, all scales predicted LVO (n=46; P&lt;0.01, each), though leukoaraiosis attenuated diagnostic accuracy and was associated with more false negative diagnoses. After adjustment, the FAST-ED (OR 3.2 [1.1-9.5]; P=0.033), and RACE (OR 3.7 [1.3-10.8]; P=0.015) but not 3I/SS (OR 5.4 [0.86-33.9]); P=0.073), VAN (OR 2.5 [0.8-7.2]), and CPSSS (OR 2.8 [1.0-8.0]) predicted LVO. Conclusion: The diagnostic accuracy of the tested LVO scales was attenuated by moderate-tosevere leukoaraiosis. If confirmed, this information may aid acute decision making and the design of studies that require LVO scale screening of patients likely to have concomitant leukoaraiosis.

Abstract WP226: Bypassing Interhospital Transfers for Large Vessel Occlusions in the Era of Mobile Stroke Units

Introduction: Mobile stroke units (MSU) provide prehospital intravenous thrombolysis (IVT) for patients with acute ischemic strokes and transport to thrombectomy-capable stroke centers. Door-in-door-out (DIDO) time is recognized as a measure of efficient workflow for interhospital transfer of patients for thrombectomy. We applied this measure to the MSU and compared with our Primary Stroke Center (PSC) transfer process in patients presenting with large vessel occlusions. Methods: We identified 50 patients who underwent thrombectomy for large vessel occlusion in a retrospective review. Mode of transport included MSU (n=18), conventional ambulance from PSC to Comprehensive Stroke Center (CSC) (n=19), or directly presenting to a CSC (n=13) in 2016-2017. Measured outcomes included times for PSC DIDO, MSU DIDO (MSU door to scene departure), door-to-CT, door-to-needle (DTN), and door-to-groin. Results: Among thrombectomy patients, IVT was more likely to be administered in a MSU (55.6%, n=10), than either a PSC (36.8%, n=7) or CSC (38.5%, n=5). Door-to-CT completed times were significantly lower in the MSU versus PSC (27 vs. 44 minutes, p&lt;0.01). DTN times in MSU were significantly shorter than PSC DTN times (27 vs. 56 minutes, p&lt;0.01), as were the median DTN times between CSC vs. PSC (27 vs. 56 minutes, p=0.09). Median DTN times comparing CSC vs. MSU were the same (27 minutes, p=0.33). DIDO time was reduced for MSU patients compared to PSC patients (27 vs. 87 minutes, p&lt;0.01). Door-to-groin times for MSU patients compared to PSC patients was significantly reduced (97 minutes vs. 171 minutes, p&lt;0.01). Door-to-groin times for CSC patients were comparable to MSU patients (100 minutes vs. 97 minutes, p=0.97). Conclusion: Advanced stroke systems of care which include a MSU are highly efficient in both IVT and transport for potential thrombectomy among patients presenting with large vessel occlusion. We introduce a concept of a MSU functioning as a mobile PSC, thus bypassing interhospital transfers.

Leukoaraiosis Attenuates Diagnostic Accuracy of Large-Vessel Occlusion Scales.

Prehospital stroke scales may help identify patients likely to have large-vessel occlusion to facilitate rapid triage to thrombectomy-capable stroke centers. Scale misclassification may result in inaccurate decisions and possible harm. Pre-existing leukoaraiosis has been shown to attenuate the association between deficit type and stroke severity. We sought to determine whether leukoaraiosis affects the predictive ability of 5 commonly used large-vessel occlusion scales. We retrospectively analyzed 274 consecutive patients with stroke with available brain MR imaging and vessel imaging. We used the following large-vessel occlusion scales: the 3-Item Stroke Scale; Field Assessment Stroke Triage for Emergency Destination; Rapid Arterial Occlusion Evaluation; Vision, Aphasia, Neglect score; and Cincinnati Prehospital Stroke Severity Scale. For diagnostic scale accuracy, we assessed sensitivity, specificity, positive predictive value, negative predictive value, and κ. Multivariable logistic regression was used to determine the predictive ability of the scales after adjustment for leukoaraiosis and potential confounders. In unadjusted analyses, all scales predicted the presence of large-vessel occlusion (n = 46, P < .01 each), though diagnostic accuracy was attenuated among patients with moderate-to-severe leukoaraiosis. After adjustment, the Field Assessment Stroke Triage for Emergency Destination (OR = 3.2; 95% CI, 1.1-9.5; P = .033) and Rapid Arterial Occlusion Evaluation (OR = 3.7; 95% CI, 1.3-10.8; P = .015), but not the 3-Item Stroke Scale (OR = 5.4; 95% CI, 0.86-33.9; P = .073), Vision, Aphasia, Neglect score (OR = 2.5; 95% CI, 0.8-7.2), and Cincinnati Prehospital Stroke Severity Scale (OR = 2.8; 95% CI, 1.0-8.0), predicted large-vessel occlusion. The diagnostic accuracy of the tested large-vessel occlusion scales was attenuated in the presence of moderate-to-severe leukoaraiosis. This information that may aid the design of future studies that require large-vessel occlusion scale screening of patients who are likely to have concomitant leukoaraiosis.

Clinical Imaging Factors Associated With Infarct Progression in Patients With Ischemic Stroke During Transfer for Mechanical Thrombectomy

When transferred from a referring hospital (RH) to a thrombectomy-capable stroke center (TCSC), patients with initially favorable imaging profiles (Alberta Stroke Program Early CT Score [ASPECTS] ≥6) often demonstrate infarct progression significant enough to make them ineligible for mechanical thrombectomy at arrival. In rapidly evolving stroke care networks, the question of the need for vascular imaging at the RHs remains unsolved, resulting in an important amount of futile transfers for thrombectomy. To examine the clinical imaging factors associated with unfavorable imaging profile evolution for thrombectomy in patients with ischemic stroke initially transferred to non-TCSCs. Data from patients transferred from 1 of 30 RHs in our regional stroke network and presenting at our TCSC from January 1, 2010, to January 1, 2016, were retrospectively analyzed. Consecutive patients with acute ischemic stroke initially admitted to a non-thrombectomy-capable RH and transferred to our center for which a RH computed tomography (CT) and a CT angiography (CTA) at arrival were available for review. ASPECTS were evaluated. The adequacy of leptomeningeal collateral blood flow was rated as no or poor, decreased, adequate, or augmented per the adapted Maas scale. The main outcome was an ASPECTS decay, defined as an initial ASPECTS of 6 or higher worsening between RH and TCSC CTs to a score of less than 6 (making the patient less likely to derive clinical benefit from thrombectomy at arrival). A total of 316 patients were included in the analysis (mean [SD] age, 70.3 [14.2] years; 137 [43.4%] female). In multivariable models, higher National Institutes of Health Stroke Score, lower baseline ASPECTSs, and no or poor collateral blood vessel status were associated with ASPECTS decay, with collateral blood vessel status demonstrating the highest adjusted odds ratio of 5.14 (95% CI, 2.20-12.70; P < .001). Similar results were found after stratification by vessel occlusion level. In patients with ischemic stroke transferred for thrombectomy, poor collateral blood flow and stroke clinical severity are the main determinants of ASPECTS decay. Our findings suggest that in certain subgroups vascular imaging, including collateral assessment, can play a crucial role in determining the benefits of transfer for thrombectomy.

Immediate Vascular Imaging Needed for Efficient Triage of Patients With Acute Ischemic Stroke Initially Admitted to Nonthrombectomy Centers.

Current guidelines for endovascular thrombectomy (EVT) used to select patients for transfer to thrombectomy-capable stroke centers (TSC) may result in unnecessary transfers. We sought to determine the impact of simulated baseline vascular imaging on reducing unnecessary transfers and clinical-imaging factors associated with receiving EVT after transfer. We identified patients with stroke transferred for EVT from 30 referring hospitals between 2010 and 2016 who had a referring hospitals brain computed tomography and repeat imaging on TSC arrival available for review. Initial Alberta Stroke Program Early CT scores and TSC vascular occlusion level were assessed. The main outcome variable was receiving EVT at TSC. Models were simulated to derive optimal triaging parameters for EVT. A total of 508 patients were included in the analysis (mean age, 69±14 years; 42% women). Application at referring hospitals of current guidelines for EVT yielded sensitivity of 92% (95% confidence interval, 0.84-0.96) and specificity of 53% (95% confidence interval, 0.48-0.57) for receiving EVT at TSC. Repeated simulations identified optimal selection criteria for transfer as National Institute of Health Stroke Scale >8 plus baseline vascular imaging (sensitivity=91%; 95% confidence interval, 0.83-0.95; and specificity=80%; 95% confidence interval, 0.75-0.83). Our findings provide quantitative estimates of the claim that implementing vascular imaging at the referring hospitals would result in significantly fewer futile transfers for EVT and a data-driven framework to inform transfer policies.

Abstract TP6: Factors Influencing Infarct Progression During Ischemic Stroke Patients Transfer: Collaterals Lost is Brain Lost

Introduction: When transferred from a referring hospital (RH) to a thrombectomy capable stroke center (TCSC), patients with initially favorable imaging profile (ASPECT score ≥6) often demonstrate infarct progression significant enough to make them ineligible at arrival. We sought to determine the clinical and imaging factors associated with this phenomenon in transferred ischemic stroke patients. Methods: We identified adult stroke patients transferred from one of 30 RH between 2010 and 2016 for which (1) a RH computed tomography (CT) and (2) a CT Angiography (CTA) at arrival were available for review. ASPECT scores were evaluated by 2 raters. The adequacy of leptomeningeal collateral flow was rated as none/poor, decreased, adequate or augmented per the Maas et al (Stroke 2009), modified scale. ASPECTS decay was defined as an ASPECT initial score ≥6 worsening between RH and TCSC CTs to a score &lt;6. Results: A total of 330 patients were included in the analysis (mean age 70.2 ± 14.2, 43.3% females). Univariable subgroup analyses showed that patients with ASPECTs decay were more likely to be females (55% vs 40%, p=0.02), not on anticoagulants (4% vs 15%, p=0.01), and with higher initial NIHSS (Median [IQR] 19 [15.3-22] vs 11 [6-17], p&lt;0.001), hyperdense vessel sign on initial CT (71% vs 26%, p&lt;0.001) and poor collaterals on CTA (72% vs 19%, p&lt;0.001). In multivariable models, higher NIHSS, lower baseline ASPECTs, CTA evidence of a proximal occlusion, and none/poor collaterals were strong predictors of ASPECTs decay, with collateral status demonstrating the highest odds ratio (aOR 10.3, 95%CI: [4.1-29], p&lt;0.001). Similar results were found after stratification by vessel occlusion level. Conclusion: In ischemic stroke patients transferred for thrombectomy, poor collateral flow, stroke severity and proximal vascular occlusion, but not time interval, are the main determinants of ASPECTs decay.