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Introduction: While the goal of IV tissue plasminogen activator (TPA) is to prevent infarction, few data exist on averted stroke. Methods: Secondary analysis of a multicenter trial from 2014-2020 comparing outcomes between patients treated for stroke by mobile stroke unit (MSU) vs standard care (SC). The analytical cohort were patients with suspected stroke treated with IV TPA. The primary outcome was a time-defined averted stroke diagnosis, defined as a final diagnosis of stroke with resolution of presenting symptoms/signs by 24 hours. The secondary outcome was a tissue-defined averted stroke diagnosis, defined as a final diagnosis of stroke with resolution of presenting symptoms/signs by 24 hours and no acute infarction/hemorrhage on imaging. We used multivariable logistic regression to evaluate associations between study exposures (demographics, comorbidities, stroke characteristics) and outcomes. Results: Among 1009 patients with a median last known well-to-TPA time of 87 minutes, 276 patients (27%) had a time-defined averted stroke (31% MSU, 21% SC) and 159 patients (16%) had a tissue-defined averted stroke (18% MSU, 11% SC). Factors independently associated with time-defined averted stroke were younger age (OR, 0.98; 95% CI, 0.96-0.99), female sex (0R, 0.51; 95% CI, 0.36-0.74), hyperlipidemia (OR, 1.81, 95% CI, 1.24-2.64), normal premorbid function (0R, 2.22; 95% CI, 1.37-3.67), lower glucose (OR, 0.996; 95% CI, 0.993-0.999), lower MAP (OR, 0.991; 95% CI, 0.983-0.998), MSU care (OR, 1.77; 95% CI, 1.21-2.62), lower NIH stroke scale (OR, 0.89; 95% CI, 0.86-0.93), and no large vessel occlusion (LVO) (OR, 0.52; 95% CI, 0.32-0.83). For tissue-based averted stroke, younger age, female sex, hyperlipidemia, lower MAP, MSU treatment, lower NIH stroke scale, and no LVO were significantly associated. Conclusion: In a modern acute stroke trial, one-in-four patients treated with TPA for stroke recovered within 24 hours and one-in-six had no demonstrable brain injury on imaging. Younger age, female sex, hyperlipidemia, lower MAP, MSU care, lower stroke severity, and no LVO may increase the odds of averting stroke.

Background and Purpose— It remains unclear how experience influences outcomes after the advent of stent retriever technology. We studied the relationship between site experience and outcomes in the Trevo Acute Ischemic Stroke multicenter registry. Methods— The 24 sites that enrolled patients in the Trevo Acute Ischemic Stroke registry were trichotomized into low-volume (4 cases/month). Baseline features, imaging, and clinical outcomes were compared across the 3 volume strata. A multivariable analysis was performed to assess whether outcomes were influenced by site volumes. Results— A total of 624 patients were included and distributed as low- (n=188 patients, 30.1%), medium- (n=175, 28.1%), and high-volume (n=261, 41.8%) centers. There were no significant differences in terms of age (mean, 66±16 versus 67±14 versus 65±15; P =0.2), baseline National Institutes of Health Stroke Scale (mean, 17.6±6.5 versus 16.8±6.5 versus 17.6±6.9; P =0.43), or occlusion site across the 3 groups. Median (interquartile range) times from stroke onset to groin puncture were 266 (181.8–442.5), 239 (175–389), and 336.5 (221.3–466.5) minutes in low-, medium-, and high-volume centers, respectively ( P =0.004). Higher efficiency and better outcomes were seen in higher volume sites as demonstrated by shorter procedural times (median, 97 versus 67 versus 69 minutes; P P ≤0.0001), and higher rates of good outcome (90-day modified Rankin Scale [mRS], ≤2; 39% versus 50% versus 53.4%; P =0.02). There were no appreciable differences in symptomatic intracranial hemorrhage or 90-day mortality. After adjustments in the multivariable analysis, there were significantly higher chances of achieving a good outcome in high- versus low-volume (odds ratio, 1.67; 95% CI, 1.03–2.7; P =0.04) and medium- versus low-volume (odds ratio, 1.75; 95% CI, 1.1–2.9; P =0.03) centers, but there were no significant differences between high- and medium-volume centers ( P =0.86). Conclusions— Stroke center volumes significantly influence efficiency and outcomes in mechanical thrombectomy.

Background and Purpose— Mechanical thrombectomy (MT) devices have led to improved reperfusion and clinical outcomes in acute ischemic stroke patients with emergent large vessel occlusions; however, less than one-third of patients achieve complete reperfusion. Use of intraarterial thrombolysis in the context of MT may provide an opportunity to enhance these results. Here, we evaluate the use of intraarterial rtPA (recombinant tissue-type plasminogen activator) as rescue therapy (RT) after failed MT in the North American Solitaire Stent-Retriever Acute Stroke registry. Methods— The North American Solitaire Stent-Retriever Acute Stroke registry recruited sites within North America to submit data on acute ischemic stroke patients treated with the Solitaire device. After restricting the population of 354 patients to use of RT and anterior emergent large vessel occlusions, we compared patients who were treated with and without intraarterial rtPA after failed MT. Results— A total of 37 and 44 patients was in the intraarterial rtPA RT and the no intraarterial rtPA RT groups, respectively. Revascularization success (modified Thrombolysis in Cerebral Infarction ≥2b) was achieved in more intraarterial rtPA RT patients (61.2% versus 46.6%; P =0.13) with faster times to recanalization (100±85 versus 164±235 minutes; P =0.36) but was not statistically significant. The rate of symptomatic intracranial hemorrhage (13.9% versus 6.8%; P =0.29) and mortality (42.9% versus 44.7%; P =0.87) were similar between the groups. Good functional outcome (modified Rankin Scale score of ≤2) was numerically higher in intraarterial rtPA patients (22.9% versus 18.4%; P =0.64). Further restriction of the RT population to M1 occlusions only and time of onset to groin puncture ≤8 hours, resulted in significantly higher successful revascularization rates in the intraarterial rtPA RT cohort (77.8% versus 38.9%; P =0.02). Conclusions— Intraarterial rtPA as RT demonstrated a similar safety and clinical outcome profile, with higher reperfusion rates achieved in patients with M1 occlusions. Prospective studies are needed to delineate the role of intraarterial thrombolysis in MT.

Background and Purpose— Mechanical thrombectomy has been shown to improve clinical outcomes in patients with acute ischemic stroke. However, the impact of balloon guide catheter (BGC) use is not well established. Methods— STRATIS (Systematic Evaluation of Patients Treated With Neurothrombectomy Devices for Acute Ischemic Stroke) was a prospective, multicenter study of patients with large vessel occlusion treated with the Solitaire stent retriever as first-line therapy. In this study, an independent core laboratory, blinded to the clinical outcomes, reviewed all procedures and angiographic data to classify procedural technique, target clot location, recanalization after each pass, and determine the number of stent retriever passes. The primary clinical end point was functional independence (modified Rankin Scale, 0–2) at 3 months as determined on-site, and the angiographic end point was first-pass effect (FPE) success rate from a single device attempt (modified Thrombolysis in Cerebral Infarction, ≥2c) as determined by a core laboratory. Achieving modified FPE (modified Thrombolysis in Cerebral Infarction, ≥2b) was also assessed. Comparisons of clinical outcomes were made between groups and adjusted for baseline and procedural characteristics. All participating centers received institutional review board approval from their respective institutions. Results— Adjunctive technique groups included BGC (n=445), distal access catheter (n=238), and conventional guide catheter (n=62). The BGC group had a higher rate of FPE following first pass (212/443 [48%]) versus conventional guide catheter (16/62 [26%]; P =0.001) and distal access catheter (83/235 [35%]; P =0.002). Similarly, the BGC group had a higher rate of modified FPE (294/443 [66%]) versus conventional guide catheter (26/62 [42%]; P P =0.003). The BGC group achieved the highest rate of functional independence (253/415 [61%]) versus conventional guide catheter (23/55 [42%]; P =0.007) and distal access catheter (113/218 [52%]; P =0.027). Final revascularization and mortality rates did not differ across the groups. Conclusions— BGC use was an independent predictor of FPE, modified FPE, and functional independence, suggesting that its routine use may improve the rates of early revascularization success and good clinical outcomes. Clinical Trial Registration— URL: https://www.clinicaltrials.gov . Unique identifier: NCT02239640.

Background and Purpose: The clinical efficacy of mechanical thrombectomy (MT) has been unequivocally demonstrated in multiple randomized clinical trials (RCTs). However, these studies were performed in carefully selected centers and utilized strict inclusion criteria. We aim to assess the clinical effectiveness of MT by comparing the specific RCT populations with corresponding patient cohorts derived from a prospective registry. Methods: A total of 2008 patients from 76 sites across 12 countries were enrolled in a prospective open-label MT registry. Patients were categorized into the corresponding cohorts of the SWIFT-Prime, DAWN, and DEFUSE 3 trials based on the age, baseline NIHSS, occlusion site, IV tPA use, pre-morbid mRS and time to treatment criteria used in the RCTs without considering specific parenchymal imaging findings. Baseline and outcome variables were compared across the corresponding groups. Results: As compared to the treated patients in the actual trials, registry-derived patients tended to be younger and had lower baseline ASPECTS. In addition, time to treatment was earlier and the use of IV tPA and general anesthesia were higher in DAWN- and DEFUSE 3-registry derived patients versus their corresponding trials. Reperfusion rates were higher in the registry patients. The rates of 90-day good outcome (mRS 0-2) in registry-derived patients were comparable to those of the patients treated in the corresponding RCTs (SWIFT-Prime, 64.5% vs 60.2%; DAWN, 50.4% vs 48.6%; Beyond-DAWN: 52.4% vs 48.6%; DEFUSE 3, 52% vs 44.6%, respectively; all P>0.05). Registry-derived patients had significant less disability than the corresponding RCT controls (ordinal mRS shift OR, P Conclusion: Our study provides favorable generalizability data for the safety and efficacy of thrombectomy in the “real-world” setting and supports that patients may be safely treated outside the constraints of RCTs and strict guidelines.

Background and Purpose: Advanced imaging has been increasingly used for patient selection in endovascular stroke therapy. The impact of imaging selection modality on endovascular stroke therapy clinical outcomes in extended time window remains to be defined. We aimed to study this relationship and compare it to that noted in early-treated patients. Methods: Patients from a prospective multicentric registry (n=2008) with occlusions involving the intracranial internal carotid or the M1- or M2-segments of the middle cerebral arteries, premorbid modified Rankin Scale score 0 to 2 and time to treatment 0 to 24 hours were categorized according to treatment times within the early (0–6 hour) or extended (6–24 hour) window as well as imaging modality with noncontrast computed tomography (NCCT)±CT angiography (CTA) or NCCT±CTA and CT perfusion (CTP). The association between imaging modality and 90-day modified Rankin Scale, analyzed in ordinal (modified Rankin Scale shift) and dichotomized (functional independence, modified Rankin Scale score 0–2) manner, was evaluated and compared within and across the extended and early windows. Results: In the early window, 332 patients were selected with NCCT±CTA alone while 373 also underwent CTP. After adjusting for identifiable confounders, there were no significant differences in terms of 90-day functional disability (ordinal shift: adjusted odd ratio [aOR], 0.936 [95% CI, 0.709–1.238], P =0.644) or independence (aOR, 1.178 [95% CI, 0.833–1.666], P =0.355) across the CTP and NCCT±CTA groups. In the extended window, 67 patients were selected with NCCT±CTA alone while 180 also underwent CTP. No significant differences in 90-day functional disability (aOR, 0.983 [95% CI, 0.81–1.662], P =0.949) or independence (aOR, 0.640 [95% CI, 0.318–1.289], P =0.212) were seen across the CTP and NCCT±CTA groups. There was no interaction between the treatment time window (0–6 versus 6–24 hours) and CT selection modality (CTP versus NCCT±CTA) in terms of functional disability at 90 days ( P =0.45). Conclusions: CTP acquisition was not associated with better outcomes in patients treated in the early or extended time windows. While confirmatory data is needed, our data suggests that extended window endovascular stroke therapy may remain beneficial even in the absence of advanced imaging.

Background: In large vessel occlusion stroke, intracranial navigation of large-bore aspiration catheters can be impeded by vessel curvature and ophthalmic artery origin. Novel conically-shaped delivery assist devices are designed to facilitate delivery. We assessed aspiration catheter deliverability in several patient-specific in vitro models. Methods: In a flow model replicating vascular access from the femoral to the middle cerebral artery, two different commercially available aspiration catheters were repeatedly advanced through a commercial 0.088” sheath from the carotid bifurcation to the middle cerebral artery by five neurointerventionalists under fluoroscopy. Three craniocervical access scenarios were manufactured based on challenging patient anatomy. Catheter deliverability was assessed with standard microwire/microcatheter combinations (MC) and the Tenzing™ 7 catheter (T7). Procedural characteristics were recorded, and operators rated carotid artery deflection, guide catheter pushback and difficulty passing the ophthalmic artery origin on a 5-point scale (1=none, 5=most severe). Results: Among 117 delivery attempts, the target vessel was reached significantly more often with T7 (96%) than with MC (66%, p Conclusion: Compared to microcatheter & microwire combinations, the T7 delivery assist catheter significantly facilitates aspiration catheter delivery to the target vessel in vitro.

Background and Purpose— In acute ischemic stroke, fast and complete recanalization of the occluded vessel is associated with improved outcomes. We describe a novel measure for newer generation devices: the first pass effect (FPE). FPE is defined as achieving a complete recanalization with a single thrombectomy device pass. Methods— The North American Solitaire Acute Stroke Registry database was used to identify a FPE subgroup. Their baseline features and clinical outcomes were compared with non-FPE patients. Clinical outcome measures included 90-days modified Rankin Scale score, National Institutes of Health Stroke Scale score, mortality, and symptomatic intracranial hemorrhage. Multivariate analyses were performed to determine whether FPE independently resulted in improved outcomes and to identify predictors of FPE. Results— A total of 354 acute ischemic stroke patients underwent thrombectomy in the North American Solitaire Acute Stroke registry. FPE was achieved in 89 out of 354 (25.1%). More middle cerebral artery occlusions (64% versus 52.5%) and fewer internal carotid artery occlusions (10.1% versus 27.7%) were present in the FPE group. Balloon guide catheters were used more frequently with FPE (64.0% versus 34.7%). Median time to revascularization was significantly faster in the FPE group (median 34 versus 60 minutes; P =0.0003). FPE was an independent predictor of good clinical outcome (modified Rankin Scale score ≤2 was seen in 61.3% in FPE versus 35.3% in non-FPE cohort; P =0.013; odds ratio, 1.7; 95% confidence interval, 1.1–2.7). The independent predictors of achieving FPE were use of balloon guide catheters and non-internal carotid artery terminus occlusion. Conclusions— The achievement of complete revascularization from a single Solitaire thrombectomy device pass (FPE) is associated with significantly higher rates of good clinical outcome. The FPE is more frequently associated with the use of balloon guide catheters and less likely to be achieved with internal carotid artery terminus occlusion.

Background and Purpose— Mechanical thrombectomy with stent retrievers has become standard of care for treatment of acute ischemic stroke patients because of large vessel occlusion. The STRATIS registry (Systematic Evaluation of Patients Treated With Neurothrombectomy Devices for Acute Ischemic Stroke) aimed to assess whether similar process timelines, technical, and functional outcomes could be achieved in a large real world cohort as in the randomized trials. Methods— STRATIS was designed to prospectively enroll patients treated in the United States with a Solitaire Revascularization Device and Mindframe Capture Low Profile Revascularization Device within 8 hours from symptom onset. The STRATIS cohort was compared with the interventional cohort of a previously published SEER patient-level meta-analysis. Results— A total of 984 patients treated at 55 sites were analyzed. The mean National Institutes of Health Stroke Scale score was 17.3. Intravenous tissue-type plasminogen activator was administered in 64.0%. The median time from onset to arrival in the enrolling hospital, door to puncture, and puncture to reperfusion were 138, 72, and 36 minutes, respectively. The Core lab–adjudicated modified Thrombolysis in Cerebral Infarction ≥2b was achieved in 87.9% of patients. At 90 days, 56.5% achieved a modified Rankin Scale score of 0 to 2, all-cause mortality was 14.4%, and 1.4% suffered a symptomatic intracranial hemorrhage. The median time from emergency medical services scene arrival to puncture was 152 minutes, and each hour delay in this interval was associated with a 5.5% absolute decline in the likelihood of achieving modified Rankin Scale score 0 to 2. Conclusions— This largest-to-date Solitaire registry documents that the results of the randomized trials can be reproduced in the community. The decrease of clinical benefit over time warrants optimization of the system of care. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT02239640.

Background and Purpose- It remains unclear how experience influences outcomes after the advent of stent retriever technology. We studied the relationship between site experience and outcomes in the Trevo Acute Ischemic Stroke multicenter registry. Methods- The 24 sites that enrolled patients in the Trevo Acute Ischemic Stroke registry were trichotomized into low-volume (2 cases/month), medium-volume (2-4 cases/month), and high-volume centers (4 cases/month). Baseline features, imaging, and clinical outcomes were compared across the 3 volume strata. A multivariable analysis was performed to assess whether outcomes were influenced by site volumes. Results- A total of 624 patients were included and distributed as low- (n=188 patients, 30.1%), medium- (n=175, 28.1%), and high-volume (n=261, 41.8%) centers. There were no significant differences in terms of age (mean, 66±16 versus 67±14 versus 65±15; P=0.2), baseline National Institutes of Health Stroke Scale (mean, 17.6±6.5 versus 16.8±6.5 versus 17.6±6.9; P=0.43), or occlusion site across the 3 groups. Median (interquartile range) times from stroke onset to groin puncture were 266 (181.8-442.5), 239 (175-389), and 336.5 (221.3-466.5) minutes in low-, medium-, and high-volume centers, respectively (P=0.004). Higher efficiency and better outcomes were seen in higher volume sites as demonstrated by shorter procedural times (median, 97 versus 67 versus 69 minutes; P0.001), higher balloon guide catheter use (40% versus 36% versus 59%; P≤0.0001), and higher rates of good outcome (90-day modified Rankin Scale [mRS], ≤2; 39% versus 50% versus 53.4%; P=0.02). There were no appreciable differences in symptomatic intracranial hemorrhage or 90-day mortality. After adjustments in the multivariable analysis, there were significantly higher chances of achieving a good outcome in high- versus low-volume (odds ratio, 1.67; 95% CI, 1.03-2.7; P=0.04) and medium- versus low-volume (odds ratio, 1.75; 95% CI, 1.1-2.9; P=0.03) centers, but there were no significant differences between high- and medium-volume centers (P=0.86). Conclusions- Stroke center volumes significantly influence efficiency and outcomes in mechanical thrombectomy.

Background: The time dependent benefit of rt-PA in acute stroke patients is established. However, only limited data exist on LVO outcomes post remote telemedicine administered rt-PA. We report the outcomes of such patients. Methods: A retrospective study of the CPMC stroke database was performed. Primary outcome measures were neurologic outcome at discharge, mortality, and TICI reperfusion scores of mechanical thrombectomy (MT) treated patients. The safety outcome measure was symptomatic hemorrhage rate (SICH; NIHSS > 1 at ≤ 36hr). Results: From 1/2014-2/2018, 233 transferred rt-PA patients were identified. Median age was 73, and median NIHSS 6. Risk factors included hypertension (69%), dyslipidemia (43%), AF (27%), prior stroke/TIA (26%), CAD (26%), DM (24%), smoking (16%), and CHF (13%). The post rt-PA SICH rate was 4% and discharge mRS≤2 rate was 43%. Mortality rate was 11%, 43% required help at discharge, and 40% were discharged home. For the 61 patients who received rt-PA + MT, the SICH rate was 2% and mortality rate 12%. Median discharge NIHSS was 2 and mRS ≤2 rate was 19%. Of the 233 transferred patients, 40 had a pre rt-PA CTA with LVO available for review. For these patients, median time to scan was 76 min. Median time to repeat CTA at CPMC was 180 min. LVO was 80% anterior circulation, clot migration was seen in 5%, and >90% of MT patients had AF. Post rt-PA recanalization rate was 12% (0% posterior circulation). MT after rt-PA was performed in 62% (TICI ≥ 2b 88%). Longer time to treatment trended towards poorer result and longer MT time. Average NIHSS dropped from 12 to 5 and average discharge mRS was 3. Conclusions: These data confirm that remote IV rt-PA followed by MT is safe and effective. Of LVO rt-PA patients 17% experienced full or partial recanalization suggesting repeat imaging is appropriate before initiating MT, possibly with the exception of posterior circulation strokes because of poor response to rt-PA. AF is common and may predict need for MT after rt-PA. A trend was observed towards improved TICI score and shorter recanalization time with a shorter latency between rt-PA and MT. These data support the use of stroke systems of care to ensure rapid triage and treatment of LVO patients.

Background: Combined neuroprotection with endovascular therapy may improve clinical outcomes of only a subset of individuals treated for acute ischemic stroke. The risk/benefit profile of adjunctive treatment may not warrant neuroprotection with successful reperfusion, yet many other individuals have poor outcomes despite revascularization. We hypothesized that optimal candidates for adjunctive neuroprotection may be defined by analyses of subjects with poor clinical outcome despite successful reperfusion in the Trevo Retriever Registry. Methods: The Trevo Retriever Registry dataset was analyzed to define the subset of cases with poor clinical outcome (day 90 mRS 4-6) after successful reperfusion (eTICI 2b50, 2b67, 2c, 3). Multivariate analyses were used to identify predictors of poor outcome using these distinct definitions of successful reperfusion. The influence of covariates, including TLSW, baseline clinical and imaging variables (e.g. ASPECTS, ASITN collateral grade), on defining such optimal neuroprotective candidates was delineated. Results: Successful reperfusion adjudicated by core lab, defined as eTICI ≥ 2b50 included 1,162 subjects, with eTICI ≥ 2b67 in 920, eTICI ≥ 2c in 652 and eTICI 3 in 209. Poor outcome (day 90 mRS 4-6) occurred in 316/1162 (27%) with eTICI ≥ 2b50, 243/920 (26%) with eTICI ≥ 2b67, 172/652 (26%) with eTICI ≥ 2c and 61/209 (29%) with eTICI 3. Across all subsets, multivariate analyses to predict poor outcome after successful reperfusion identified increased age (per year, OR 1.04-1.05, all p= Conclusions: Neuroprotection combined with endovascular therapy may optimally target stroke patients with worse collaterals, diabetes or increased age. Trial design for neuroprotection with revascularization in AIS should leverage these data.

Background: Two recent trials showed a strong benefit of thrombectomy in the extended window. However, these studies were performed in selected centers and utilized strict inclusion criteria. We aim to evaluate the outcomes of thrombectomy in a large prospective cohort treated outside the rigid clinical trial setting. Methods: Trevo Registry patients with ICA, MCA-M1 or M2 occlusions and pre-morbid mRS0-2 were categorized according to time-from-last-seen-well (TLSW) to puncture as early (0-6hours) vs. late (6-24hours). Uni- and multivariate analyzes were performed to identify good outcome (90-day mRS0-2) predictors. Subgroup analyses were performed for the basic DAWN (age >=18, NIHSS >=10, ICA or M1 occlusion, pre-morbid mRS 0-1) and DEFUSE 3 (age 18-90, NIHSS >=6, ICA or MCA-M1 occlusion, mRS 0-2) trial criteria. Results: As compared to the late (n=430), early patients (n=1173) were older (70 vs 68, p=0.011) and had higher IV tPA use (69 vs 25%, p= 6 (1.37 [1.07-1.75]), DM (0.58 [0.44-0.77]), and time to treatment (0.98 [0.97-1.00]) were independent predictors of good outcomes. Imaging modality did not predict outcomes. Similar findings were observed in the early versus late DAWN-like (n=709 vs 257) and DEFUSE 3-like (n=855 vs 273) cohorts. There was great similarity between the outcomes of the Trevo Registry subsets vs their analogous RCTs: early DAWN-like vs SWIFT Prime (90-day mRS 0-2: 57.5 vs 60%; 90-day mRS 6: 11.% vs 9%), Late DAWN-like vs DAWN (50.2 vs 48.6%; 10.6 vs 18%), and Late DEFUSE 3-like vs DEFUSE 3 (52 vs 45%; 10.3 vs 14%). Conclusions: Our study provides favorable data for the generalizability of the safety and efficacy of thrombectomy in the “real-world” setting.

Background: Time to reperfusion (TTR) is commonly cited in clinical outcome after endovascular treatment of acute ischemic stroke, yet collaterals may set the pace of ischemia. Real-world data on fast and slow progressors also remain scarce. We analyzed the impact of TTR on clinical outcome in real-world data using core lab adjudicated angiography, interventional steps and corresponding reperfusion. Methods: 16 key time intervals were calculated from workflow (time of symptom onset, door, picture, puncture) and core lab metrics (clot visualization, first deployment, first reperfusion, final angiography) in real-world data from the Trevo Retriever Registry. These 16 variations of TTR were analyzed overall and by collateral status (ASITN 0-1 versus 2 versus 3-4) to determine the relationship with 90-day clinical outcomes. Results: Real-world data on endovascular therapy from 1,441 subjects in the Trevo Retriever Registry were analyzed to relate TTR with clinical outcomes. Overall metrics for TTR are shown in Table 1. TTR was not linked with collateral status. Using a multivariate model incorporating known predictors, there was no influence of TTR using any of the 16 definitions on clinical outcome. Better collateral status on DSA prior to revascularization showed a potent relationship with 90-day mRS (p Conclusions: Collaterals transform time to reperfusion, linking fast and slow progressors with subsequent clinical outcomes. TTR may be standardized based on these 16 key epochs in endovascular stroke therapy to document workflow metrics. Time is relative, even when measured with detailed, standardized metrics.

Background: Time to mechanical thrombectomy is a significant driver of outcomes in acute ischemic stroke (AIS) patients presenting with large vessel occlusion (LVO). We aimed to evaluate predictors of onset to groin puncture (OTG), groin puncture to reperfusion (GTR), and onset to reperfusion (OTR) times in AIS patients treated with the Trevo stent-retriever. Methods: The investigator-initiated TRACK registry recruited 23 clinical sites to submit demographic, clinical, site-adjudicated angiographic, and outcome data on consecutive patients treated with the Trevo device. We included patients treated Results: Among 433 patients analyzed (mean age 66.8 +/- 14.6 years; median NIHSS score 18; 88% anterior circulation), the median times were: OTG 240, GTR 64, and OTR 321 minutes. In multivariable analysis (Table), the independent predictors were: 1) OTG: transfer status and general anesthesia (GA) use; 2) GTR: 1 pass attempt only, use of rescue therapy, GA use, and baseline mRS >1; and 3) OTR: transfer status, use of perfusion imaging, anterior circulation LVO, use of rescue therapy, and 1 pass attempt only. Conclusions: Major pre-treatment contributors to delays to reperfusion in AIS patients treated

Background: The delay and dispersion of collateral circulation to the MCA territory is readily available prior to endovascular thrombectomy for acute ischemic stroke (AIS). Factors associated with collateral grade have never been established in such an extensive population, reflecting diverse subjects from around the world. Largescale data from the Trevo Retriever Registry enables mapping of the MCA collaterome for the first time. Methods: The Imaging and Angiography Core Lab of the Trevo Retriever Registry independently conducted prospective evaluation of angiography in more than 1,500 subjects. Collaterals were systematically scored using ASITN grade prior to thrombectomy. Descriptive statistics detailed the distribution of collateral grades and analyses with demographic, imaging and clinical variables to explore key associations with routinely acquired registry data. Results: 890 subjects (68.5 ± 15.1 years; 54.6% women; baseline NIHSS median 15 (10-19)) with AIS due to MCA occlusion had angiography of collateral circulation centrally adjudicated. Proximal M1 MCA occlusion was noted in 671/890 (75.4%). Collateral grade prior to thrombectomy included grade 4 or most robust collaterals in 38/890 (4.3%), 3 in 294/890 (33.0%), 2 in 467/890 (52.5%), 1 in 80/890 (9%) and 0 or none in 11/890 (1.2%). Baseline collaterals at angiography and pre-procedure ASPECTS were closely correlated (r=0.439, p6s) hypoperfusion at-risk (r=-0.10, n=391; p=0.043) volumes. First pass mTICI≥2b occurred in 553/858 (64.5%) with final mTICI≥2b in 824/890 (92.6%). Collateral grade prior to thrombectomy (each 1-point increment, after adjustment for other predictors) was strongly associated (OR 1.38 95%CI (1.12-1.7), p=0.002) with good clinical outcomes (mRS 0-2) at 90 days. Conclusions: Largescale mapping of collaterals prior to MCA thrombectomy reveals marked variation in the extent and functional impact of the collaterome. The preponderance of partial perfusion in the downstream ischemic territory prompts the need to investigate and leverage the protective nature of the collaterome in AIS.

Introduction: Approximately 2/3 of all AIS present with NIHSS 0-5. While it has been demonstrated that LVO can be found in ~10-20% of all low NIHSS patients, outcome data in this population remains scarce. Indeed, only 14/1766 patients in the recent endovascular RCTs had baseline (b) NIHSS in the 0-5 range. Yet, the presence of LVO in the setting of low NIHSS is associated with ~10-fold increase in subsequent deterioration. We aim to describe the outcomes in a large cohort of low NIHSS patients undergoing thrombectomy. Methods: Patients derived from a large prospective multicenter international stent-retriever registry (Trevo Registry, n=2,010). Baseline and outcome variables were compared according to bNIHSS 0-8 vs >8 and bNIHSS 0-5 vs >5. The primary and secondary efficacy endpoints were the rates of 90-day mRS 0-2 and mTICI 2b-3, respectively. Safety endpoints included sICH and 90-day mortality. Results: A total of 1,985 patients were included. As compared with patients with higher baseline NIHSS, low baseline NIHSS (0-8, n=342; 0-5, n=160) patients were younger, had less comorbidities and better functional status, more frequently had MCA-M2 or vertebrobasilar occlusions, less frequently received IV tpa, and underwent thrombectomy at later times (Table 1). The reperfusion outcomes were nearly the same. There were no significant differences in procedure-related complications, which were overall low (Table 2). The rates of 90-day mRS 0-2 were significantly higher in the lower NIHSS patients (p Conclusion: Despite safe and efficacious endovascular reperfusion, low-NIHSS LVO patients have a relatively high proportion of bad outcomes. This supports the notion that many of "mildly" presenting patients do not fare well. A randomized clinical trial including immediate endovascular treatment in this patient population is warranted.

Background and Aims: Balloon Guide Catheter (BGC) use during thrombectomy treatment in Stroke patients has been reported to have positive effects on revascularization, procedural characteristics, and clinical outcomes. We evaluate the use of BGC in an open-label large prospective TREVO Retriever Registry of real world patients to determine predictors of good ‘clinical’ outcomes. Method: Consecutive Trevo Registry patients that had Balloon Guide Catheter (BGC) used during their thrombectomy procedure were identified; a subset of patients who fulfilled the criteria (ICA and/or MCA-M1/M2 occlusion with pre-morbid mRS 0-1, TLSW ≤6 hrs) within the cohort were also identified. Multivariate analysis was performed to identify the predictors of good outcomes in BGC thrombectomy patients. Results: A total of 1031 BGC treated Trevo Registry patients (overall enrolled, n=2010) qualified for analysis, of which 605 patients fulfilling the subset criteria were identified. The mean age of BGC/stent retriever patients was 67.5 with a median (IQR) baseline NIHSS of 15(11-19). Occlusion location of the BCG group was ICA -20.4%, M1- 57.1%, M2/M3-20.3%, and Posterior 1.8%. In the overall BGC cohort, the median (IQR) time to treatment was (4.2 (3.0,6.5)- hrs.) with conscious/local sedation used in 63.4% and general anesthesia used in 37.3% of cases. The median number of passes with Trevo stent retriever was 1 and revascularization (mTICI ≥ b) was achieved in 92.8% of cases. The sICH rate was low at 1.9% (20/1031) with a low rate of vessel perforation (0.2%). At 90 days post stroke, 56.0% of patients achieved functional independence (mRS 0-2) with 63.7% of the subset of “guidline “ BGC patients achieving functional independence at 90 days. Multivariate logistic regression showed age (aOR 0.97 [0.96, 0.99] P Conclusion: Data from Trevo Registry demonstrate the use of BGC in thrombectomy procedure is safe, and leads to a reduction of disability in ischemic stroke patients.

Introduction: The recent thrombectomy trials were largely limited to patients with small strokes on presentation. Methods: Patients derived from a large prospective multinational stent-retriever registry (Trevo Registry, n=2,010). Baseline NCCT SPECTS and CTP Core Volumes (rCBF70mL if age 50mL if age >70-80 years; >30mL if age >80 years) vs. not on CTP. The primary and secondary efficacy endpoint were the rates of 90-day mRS 0-2 and mTICI 2b-3, respectively. Safety endpoints included sICH and 90-day mortality. Results: As compared with patients with higher baseline ASPECTS (n=1037), low baseline ASPECTS (0-4, n=78; 5, n=78) patients were younger, had higher stroke severity, and tend to have less comorbidities and undergo thrombectomy at later times (Table 1a). TICI-3 reperfusion was higher in the higher-ASPECTS group but other reperfusion outcomes were nearly the same. Safety outcomes were comparable. Rates of 90-day mRS 0-2 were significantly higher in the high-ASPECTS group (p Conclusion: Patients with large baseline cores as measured by either NCCT or CTP may still achieve favorable outcomes with endovascular treatment. A randomized clinical trial in this patient population is warranted.

Background: Routine use of advanced imaging versus ASPECTS for imaging triage of endovascular thrombectomy candidates has not been evaluated on a large scale to date. Ischemic core may be defined by ASPECTS or perfusion imaging, yet these variable definitions likely reflect different pathophysiology as perfusion may fluctuate and ASPECTS lesions may be time-dependent. Methods: The Trevo Retriever Registry was a prospective, open-label, consecutive enrollment, multicenter, international registry with more than 65 enrolling sites worldwide. The Imaging and Angiography Core Lab systematically adjudicated more than 1,500 subjects, scoring ASPECTS and separately processing perfusion imaging. Ischemic core volume on perfusion imaging was defined as rrCBF Results: 488 subjects (68.3±14.4 years; 53.3% women; baseline NIHSS median 15 (10-19) with anterior circulation occlusions were evaluated with both ASPECTS and perfusion imaging prior to thrombectomy. Arterial occlusions included 87/487 (17.9%) ICA and 296/487 (60.8%) proximal M1 MCA, treated with thrombectomy at median 4.7 (3.3-7.9) hours from time last known well (TLKW). ASPECTS was median 8 (7-9) with ischemic core lesions of median 18 (4.9-39.2) cc. At-risk hypoperfusion (Tmax>6s) lesions were median 109.8 (62-156.9) cc. TLKW was associated with ASPECTS (r=-0.18, p Conclusions: Largescale, systematic evaluation of ASPECTS and perfusion imaging prior to thrombectomy reveals discrepancy in the definition of ischemic core and the prediction of clinical outcomes after revascularization. ASPECTS is time-dependent, yet reliably predicts outcomes in routine clinical practice.

Background: Endovascular therapy (EVT) effectiveness is established in ischemic strokes with large vessel occlusion (LVO) in the terminal ICA and M1, which was extended up to 24 hrs by recent DAWN trial results. However this benefit is not as well established in more distal (M2) occlusions, especially late presenters (beyond 6 hrs). We evaluated thrombectomy outcomes in M2 occlusions as compared to ICA/M1 across early and late time windows. Methods: In a prospective, multicenter, single arm, international registry (Trevo Retriever Registry), anterior circulation LVOs were stratified on clot location into M2 vs ICA/M1 and dichotimized into early vs late (0-6 vs 6-24 hrs). 90 day mRS (0-1 excellent, 0-2 good) were the primary outcomes; sICH and dissection were the secondary (safety) outcomes. Multivariate analyses identified pre-procedure variables independently correlating with good outcome in M2s. Results: 1581 patients were identified (1265 ICA/M1, 316 M2). The M2 and ICA/M1 groups were similar (age in both 68.4), IV-tPA (69.1 vs 69.7%, p=0.8) and same median/IQR ASPECTS 8 (7-9). M2 patients had lower NIHSS (13 vs 16, p Conclusion: Excellent and good outcomes may be achieved in distal LVO isolated to M2 similar to those with proximal occlusions. A benefit that can be reached up to 24 hrs.

Objective: The Trevo Registry was designed to assess real world outcomes of the Trevo Retriever in patients experiencing ischemic stroke. It is the largest prospective study for acute stroke intervention, with 2010 patients enrolled and 90 day outcomes in 1873 patients. The primary endpoint is revascularization status based on post-procedure TICI score and secondary endpoints include 90-day mRS, 90-day mortality, neurological deterioration at 24 hours and device/procedure related adverse events. Methods: The study was a prospective, open-label, consecutive enrollment, multi-center, international registry of patients who underwent mechanical thrombectomy for acute stroke using the Trevo stent retriever as the initial device. Results: The median NIHSS at admission was 16 (IQR 11-20). Most patients (70.8%) were treated at Conclusions: The Trevo Retriever Registry represents the first real world data with stent retriever use in the era of clinical trials showing the overwhelming benefit of stent retrievers to treat acute ischemic stroke. Due to the fact that this data represents real world use of the Trevo Retriever, (e.g. subjects pre-stroke mRS >1 (29%) and those treated 6-24 hours after stroke symptoms (29%), this data cannot be compared to the results from recent trials with restricted eligibility criteria. Future subgroup analysis of this large cohort will help to identify areas of future research to enhance outcomes further with this treatment modality.

Background and Aims: Intravenous tPA remains the standard of care, with MT currently indicated within 8 hours for IV tPA failures or patients with IV tPA contraindications. Whether LVO patients should receive IV tPA treatment or instead be triaged directly to MT therapy is currently unknown but greatly debated. The Trevo Registry is a real world, multi-center, international study of mechanical thrombectomy (MT) patients treated from 0-24 hours. Evaluation of the Trevo Registry clinical and procedurals outcomes of MT patients treated with or without IV tPA could provide insight into the benefit of IV tPA in MT patients. We hypothesized that in MT patients treated within 8 hours, pretreatment with intravenous tPA would lead to better clinical outcomes compared to patients who did not receive IV tPA. Method: Consecutively enrolled patients treated within 8 hours with ICA, M1, or M2 occlusions were selected for analysis. Univariate and multivariable regressions were conducted to identify clinical and radiographic independent variables that correlate best with the dependent variable of functional outcome: mRS 0-2, with a focus on intravenous tPA treatment. Results: A total of 1183 Trevo Registry patients (overall enrolled, n=2010) qualified for analysis, of whom 380 were not treated with IV tPA. Demographics were similar, however atrial fibrillation (46.3% vs 27.2%) and previous ischemic stroke (14.1% vs 7.5%) were higher in the no IV tPA group. The median time to treatment was similar (3.8 vs. 3.6 hrs). First pass mTICI ≥ 2B (63.6% vs 66.4%) and final revascularization (91.1% vs 92.8%) were similar between no IV tPA and IV tPA groups.Unadjusted, there were similar rates of functional outcome (90 day mRS 0-2; 60.9% vs. 62.5%). After adjustment, patients who did not receive IV-tPA had similar rates of good outcome (aOR 1.08, 95% CI [0.87-1.34]. P=0.58) as well as reduction (shift) in disability (aOR 1.08, 95% CI [0.87-1.34]. P=0.49). Safety outcomes (mortality, sICH) were similar between both groups. Conclusion: In the Trevo Registry of MT patients treated within 8 hours, patients who did not receive IV tPA had similar endovascular and clinical outcomes as patients pretreated with IV tPA. The added benefit of IV tPA for MT patients should be further investigated.

Background: The DAWN trial showed EVT effectiveness in the late time window (6-24 hrs), however, DAWN patients were carefully selected based on advanced perfusion imaging, CTP and MRI. Similar to the early window (0-6 hrs), simple imaging (CT) and other clinical variables may select patients for thrombectomy beyond 6 hours. We evaluated a largescale, real world practice for predictors that could identify patients who may benefit from EVT in the late time window. Methods: Patients with LVO in the anterior circulation (M1, M2, ICA) from a prospective, single arm, multicenter, international registry (Trevo Retriever Registry) treated in the late window LSN to groin puncture (GP) (6-24 hrs) were included. Univariate and multivariate analyses assessed factors independently correlating with good outcome (90 day mRS 0-2). Furthermore, patients outcomes were compared based on their baseline imaging selection CT vs CTP and MRI. Results: 549 patients were treated beyond 6 hours. The average age was 67, median/IQR ASPECTS 8(6-9), median/IQR NIHSS was 15 (9-20), median/IQR time LSN to GP (hr) was 9.7 (7.3-13.6) and IV-tPA rate were 22.8%. CT was the only imaging selection method in 15.9%, while additional advanced imaging was utilized in the remaining patients; CTP (70%), and MRI(14.1%). Good outcomes were observed in 51.4% of late window patients. Age (aOR 0.96, 95% CI 0.94-0.98, p Conclusion: Simple imaging and clinical variables can identify patients that could benefit from thrombectomy in the late window. Importantly, ASPECTS reliably predicted good outcome beyond 6 hours without adjunctive benefit from adding advanced perfusion imaging, a finding that may simplify patients selection to facilitate and generalize the intervention in the late window to wide, real world practice.

Background and Purpose— Failure to recanalize predicts mortality in acute ischemic stroke. In the North American Solitaire Acute Stroke registry, we investigated parameters associated with mortality in successfully recanalized patients. Methods— Logistic regression was used to evaluate baseline characteristics and recanalization parameters for association with 90-day mortality. A multivariable model was developed based on backward selection with retention criteria of P P ≤0.10), then refit to minimize the number of excluded cases (missing data). Results— Successfully recanalized patients had lower mortality (25.2% [59/234] versus 46.9% [38/81] P P =0.205). However, mortality was significantly higher in patients with symptomatic intracranial hemorrhage (72% [23/32] versus 26% [73/281]; P P P c index=0.72), proximal occlusion, initial National Institutes of Health Stroke Scale≥18, and use of rescue therapy remained significant independent predictors of 90-day mortality. Conclusions— Failure to recanalize and presence of symptomatic intracranial hemorrhage resulted in increased mortality. Despite successful recanalization, proximal occlusion, high National Institutes of Health Stroke Scale, and need for rescue therapy were predictors of mortality.

Background: The efficacy of endovascular therapy (EVT) in randomized clinical trials (RCTs) for acute strokes due to large vessel occlusion (LVO) led to AHA guidelines recommending EVT as standard of care for selected patients. However, many conditions were under-represented in the RCTs: ASPECTS 6 hrs and M2/ distal/ posterior circulation occlusions. Objective: We evaluated EVT outcomes in these populations compared to counterparts represented in the RCTs. Methods: A large multicenter international prospective cohort study of LVO patients treated with stent retriever thrombectomy (TREVO Registry) between 11/2013 and 4/2016 was analyzed. 90 day mRS was the primary outcome (0-2 good outcome). Multivariate logistic regression modeling was employed to evaluate EVT impact in the different groups. Results: Of 1000 patients, 81 had NIHSS p< 0.001 compared with NIHSS ≥6) (Table 1). Over 80 yo, however, had low odds of independence (aOR 0.3, 95% CI 0.2-0.5; p 6 hrs, 51% had a good outcome (aOR 0.78, 95% CI 0.55-1.1; p =0.17) compared to ≤6 hrs. Nearly half of patients with ASPECTS 6 hrs. Fig 2 demonstrates the likelihood of good outcome by clot location. M2 and distal occlusions had the highest good outcome probabilities while proximal ICAs had the lowest (48.1%). More than half of vertebrobasilar patients achieved independence (54.8%). Conclusion: While effectiveness cannot be determined in the absence of medically treated controls, our analyses of real world data show several groups outside AHA guidelines may benefit from EVT. In particular, further study is needed to examine EVT benefits for mild stroke and M2 occlusions.

Background: While faster reperfusion with EVT leads to better outcomes in acute ischemic stroke due to large vessel occlusion (LVO), most LVO patients present to outside hospitals without EVT capability. Treating physicians are often unsure if EVT would confer benefit upon arrival to tertiary hospitals given inter-facility transfer delays. Objective: We evaluated independent predictors of good outcome in transferred patients treated with EVT to devise a score that may assist treating physicians to make transfer and treatment decisions. Methods: Transfer patients were analyzed in a multicenter international prospective cohort study of LVO patients treated with stent retriever thrombectomy (TREVO Registry) from 11/2013 to 4/2016. Independent factors correlating with good outcome after EVT were identified using univariate and multivariate analyses. We devised a score to identify patients with LVO at the referral facility who may benefit from EVT. Results: Of 1000 patients enrolled, 226 were anterior circulation occlusions, transferred and treated within 0-8 hrs (Table 1). Age, stroke severity, glucose level, M2 occlusion and achieving onset to groin puncture ≤ 5 hr were independent factors associated with good outcome (Table 2). Other clinical variables were analyzed, as in ASPECTS, but were not significant. A 10 point score was devised (Table 3). Patients with a score of 0-4 had 4 times the odds of good outcome compared to a score of 5-9 (aOR 4.3, 95% CI 1.9-9.9; p p Conclusion: A simple transfer score may be an effective triage method to identify patients at remote facilities who may benefit from EVT upon transfer. Further validation is necessary to confirm these findings.

Introduction: Endovascular stroke therapy has become the gold standard treatment for large vessel occlusion. The Joint Commission has certified hospitals as Comprehensive stroke centers (JCCSC) based on rigorous standards in the hopes of identifying centers of excellence. We sought to determine if JCCSC have faster door to reperfusion times compared to non-JCCSC. Methods: The TREVO registry is a multicenter international real world registry assessing angiographic and clinical outcomes with the Trevo device being used in the first pass. We defined a CSC as certified by the Joint Commission as of July 1, 2016. Demographic information, times within the hospital, angiographic results and clinical outcomes were analyzed between the JCCSC and non-JCCSC institutions. Results: A total of 507 patients (329 JCCSC, 178 non-JCCSC) have completed data in the Trevo registry to date. There are a higher proportion of patients with ASPECTS < 7 being treated at JCCSC vs. non-JCCSC (8.8% vs. 0.0%, p Conclusions: Patients treated at a JCCSC had faster procedural times, without faster door to procedure times when compared to non-JCCSC centers. Outcomes were no different, due to imbalances in stroke severity at baseline and a higher proportion of patients with ASPECTS < 7 being treated.

Objective: The Trevo Registry is designed to assess real world outcomes of the Trevo Retriever in patients experiencing ischemic stroke. This is the largest prospective study for acute stroke intervention, with 1247 patients currently enrolled and 90 day outcomes in 1021 patients. The primary endpoint is revascularization status based on post-procedure TICI score and secondary endpoints include 90-day mRS, 90-day mortality, neurological deterioration at 24 hours and device/procedure related adverse events. Methods: The study is a prospective, open-label, consecutive enrollment, multi-center, international registry of patients undergoing mechanical thrombectomy for acute stroke using the Trevo stent retriever as the initial device. Enrollment is expected to reach 2000 subjects at up to 100 sites. Results: As of August 13, 2016 a total of 1247 patients were enrolled. The median NIHSS at admission was 16 (IQR 11-20). Most patients (66.2%) were treated at >/= 6 hours from last known normal with a median procedure time of 50 minutes (32-77). The occlusion site was M1 or M2 in 74.5%. General anesthesia was employed in 46.6% of procedures. TICI 2b or 3 revascularization was 92.8% with an average of 1.6 passes with the device. Median NIHSS at 24 hours and discharge was 6 and 4 respectively. Fifty-five percent of patients had mRS ≤2 at 3 months and the overall mortality rate was 15.4%. Patients treated after 8 hours of symptom onset had a 94.9% revascularization rate and 52.8% mRS ≤2 at 3 months. The symptomatic ICH rate was 1.2%. Patients who met the revised AHA criteria for thrombectomy were found to have 58.4% mRS 0-2 at 90 days. Conclusions: The Trevo Retriever Registry represents the first real world data with stent retriever use in the era of clinical trials showing the overwhelming benefit of stent retrievers to treat acute ischemic stroke. Due to the fact that this data represents real world use of the Trevo Retriever, (e.g. subjects pre-stroke mRS >1 (16.5%) and those treated 6-24 hours after stroke symptoms (33.8%), this data cannot be compared to the results from recent trials with restricted eligibility criteria. Future subgroup analysis of this large cohort will help to identify areas of future research to enhance outcomes further with this treatment modality.

Background: Endovascular thrombectomy (EVT) substantially increases the likelihood of good outcome in acute ischemic strokes due to large vessel occlusion (LVO). Expediting EVT to achieve faster reperfusion is an important factor that correlates with good outcome. Ultra-early intervention in the first 3 “golden” hours from onset was not well characterized in recent trials. Objective: We sought to assess the impact of early treatment within the first 3 hours on clinical outcomes in large, real life, world-wide practice. Methods: We analyzed a multicenter international prospective cohort study of LVO patients treated with stent retriever thrombectomy (TREVO Registry) between11/2013 and 4/2016. We stratified patients based on treatment time, onset to groin puncture (GP), into 3 groups: 0-3, 3-6, >6 hrs. 90 day mRS was the primary outcome (0-2 good outcome). Logistic regression modeling was performed to evaluate the impact of treatment within the golden 3 hours on outcomes and to determine the independent factors associated with EVT initiation within 3 hours. Results: In the 905 patients, GP occurred in: 23.1% 0-3 hrs, 44.3% 3-6 hrs and 32.6% >6 hrs. Table 1 shows similar baseline characteristics among the groups. Patient-level predictors of treatment within 3 hrs were age (aOR 1.1 per decade of age ≥18) and good ASPECTS (aOR 1.2 per point). No hospital-level predictors of early treatment were found. Patients treated within 3 hrs have a higher likelihood of good outcome as compared to those treated >3 hrs (aOR 2.0, 95% CI 1.4-2.9; p Conclusion: Early thrombectomy of LVO strokes, within the first three hours provides the highest impact compared with later time windows. Streamlining processes to deliver rapid intervention within 3 hours would improve clinical outcomes.

Background: Endovascular thrombectomy trials established efficacy in acute ischemic stroke, yet real-world data on device effectiveness is warranted. Core lab adjudication of angiography is required to validate reperfusion, providing evidence and detailed data beyond randomized, controlled trials. We report the largest endovascular therapy registry data linking independent core lab data on reperfusion with clinical outcomes. Methods: The Trevo Retriever Registry is a prospective, open-label, consecutive enrollment, multicenter, international registry with more than 65 enrolling sites worldwide. An independent Imaging Core Lab, blind to all other data, evaluates the angiography with a battery of various TICI scores (mTICI, oTICI, oTICI2C) to define reperfusion. Statistical analyses examined TICI reperfusion and association with clinical outcomes considering expansive data collected in the registry. Results: 506 enrolled subjects (mean age 68.2 ± 14.2 yrs; 53% female) had core lab adjudicated angiography as of July 2016, including 21.5% > 80 years old. Baseline NIHSS was median 15.0 (9.0, 20.0) with time from onset to CT of median 4.0 (1.7, 9.7) hrs. Core lab adjudicated arterial occlusion sites were: 53% M1, 24% ICA, 16% M2, 4% Basilar and 2% other. Time to reperfusion (oTICI ≥ 2A) was median 30.0 (19.0, 42.0) min. Core lab adjudicated revascularization was mTICI ≥ 2B in 90.4% (95%CI 87.4, 92.9), oTICI ≥ 2B in 82.3% (95%CI 78.6, 85.6) and oTICI2C ≥ 2C in 45.0% (95%CI 40.5, 49.6). mRS of 0-2 at 90 days was achieved in 57.3% (95%CI 52.5, 62.1). Extensive clinical, laboratory and stroke workflow variables were considered, yet only male sex (OR 0.62 (95% CI 0.38, 0.99) was an independent predictor of successful reperfusion (oTICI ≥ 2B) while age (OR 0.96 (95% CI 0.94, 0.97), NIHSS (OR 0.91 (95% CI 0.88, 0.94) and diabetes (OR 0.54 (95% CI 0.33, 0.88) predicted mRS 0-2 at 90 days. Conclusions: Proven reperfusion rates after endovascular stroke therapy excel in the real-world translation of thrombectomy devices around the globe, leading to good outcomes after stroke.

Background: Most endovascular stroke therapy studies and subsequent guidelines restrict intervention based on ASPECTS. A wide range of ASPECTS scores may be encountered in practice and individual patient benefit may be realized even at low ASPECTS. We examined large-scale data on outcomes after endovascular therapy, stratified by baseline ASPECTS in the Trevo Retriever Registry. Methods: The independent Imaging Core Lab of the Trevo Retriever Registry prospectively determines ASPECTS on baseline imaging acquired immediately prior to endovascular thrombectomy. ASPECTS scores and regional involvement were analyzed with respect to site of arterial occlusion, effect of time from symptom onset, co-morbidities and clinical outcomes, based on ASPECTS strata. Results: Baseline ASPECTS data was reviewed by the Imaging Core Lab in 426 subjects with anterior circulation stroke enrolled in the Trevo Retriever Registry, as of July 2016. Mean age was 68.8 ± 13.7 yrs, with 20.9% > 80 years old. Baseline NIHSS was median 15.0 (10.0, 19.0). Onset to CT was median 3.8 (1.5, 9.0) hrs, with median ASPECTS of 8.0 (7.0, 9.0), ranging from 3-10. Baseline ASPECTS 0-7 occurred in 118/426 (27.7%) subjects, including 39.0% of ICA, 27.1% M1 and 16.9% M2/3 arterial occlusions at angiography. Baseline clinical variables predicting ASPECTS included age and NIHSS, whereas the ASPECTS score was mildly associated with final TICI2C reperfusion (r=0.24, p Conclusions: Discrete ASPECTS strata may influence outcomes of endovascular therapy conducted in routine practice around the world, yet individuals with low ASPECTS may still achieve reasonable outcomes.

Background: While endovascular therapy (EVT) is effective for large vessel occlusions (LVO), most patients present to hospitals without EVT capability and are transferred for intervention, delaying treatment. Objective: We evaluated outcomes in LVO patients treated with thrombectomy who were transferred compared to those presenting directly to EVT facilities. Methods: In a large multicenter international prospective cohort study of LVO patients treated with stent retriever thrombectomy (TREVO Registry), patients were stratified by initial presentation into transferred (TNS) vs direct (DIR). 90 day mRS was the primary outcome (0-1 excellent, 0-2 good outcomes); sICH and reperfusion by mTICI were secondary outcomes. Outcomes were compared in the 2 groups (0-8 hrs onset to groin puncture (GP) then in time matched 3-8 hrs subgroups for validation). Logistic regression identified independent predictors of good outcome in TNS patients. Results: We identified 540 patients (230 TNS; 310 DIR) (Fig 1). TNS patients were younger and had longer onset to GP times (4.6 vs 3.1 hrs; p p p =0.4) (Fig 2) and no difference in the time matched 3-8 hrs subgroups (59.2% DIR vs 56.3% TNS, p =0.6). Fig 3 plots good outcome probabilities over time, showing similar confidence interval bands. Younger age (OR 0.95), lower NIHSS (OR 0.90), glucose level < 170 mg/dL (OR 2.4), distal clot location (M2) (OR 1.7), excellent reperfusion (mTICI≥2b) (OR 2) and time to GP Conclusion: While excellent outcomes were higher in directly-presenting patients, EVT-treated transfers may achieve similar good outcomes. The association between earlier EVT after transfer and better outcomes emphasizes the need to streamline the transfer process.

Background and Purpose— Previous work that predated the availability of the safer stent-retriever devices has suggested that general anesthesia (GA) may have a negative impact on outcomes in patients with acute ischemic stroke undergoing endovascular therapy. Methods— We reviewed demographic, clinical, procedural (GA versus local anesthesia [LA], etc), and site-adjudicated angiographic and clinical outcomes data from consecutive patients treated with the Solitaire FR device in the investigator-initiated North American SOLITAIRE Stent-Retriever Acute Stroke (NASA) Registry. The primary outcomes were 90-day modified Rankin Scale, mortality, and symptomatic intracranial hemorrhage. Results— A total of 281 patients from 18 centers were enrolled. GA was used in 69.8% (196/281) of patients. Baseline demographic and procedural factors were comparable between the LA and GA groups, except the former demonstrated longer time-to-groin puncture (395.4±254 versus 337.4±208 min; P =0.04), lower National Institutes of Health Stroke Scale (NIHSS; 16.2±5.8 versus 18.8±6.9; P =0.002), lower balloon-guide catheter usage (22.4% versus 49.2%; P =0.0001), and longer fluoroscopy times (39.5±33 versus 28±22.8 min; P =0.008). Recanalization (thrombolysis in cerebral infarction ≥2b; 72.94% versus 73.6%; P =0.9) and rate of symptomatic intracranial hemorrhage (7.1% versus 11.2%; P =0.4) were similar but modified Rankin Scale ≤2 was achieved in more LA patients, 52.6% versus 35.6% (odds ratio, 1.4 [1.1–1.8]; P =0.01). In multivariate analysis, hypertension, NIHSS, unsuccessful revascularization, and GA use (odds ratio, 3.3 [1.6–7.1]; P =0.001) were associated with death. When only anterior circulation and elective GA patients were included, there was a persistent difference in good outcomes in favor of LA patients (50.7% versus 35.5%; odds ratio, 1.3 [1.01–1.6]; P =0.04). Conclusions— The NASA Registry has demonstrated that clinical outcomes and survival are significantly better in patients treated with LA, without increased symptomatic intracranial hemorrhage risk. Future trials should prospectively evaluate the effect of GA on outcomes.

Background: New generation IA devices are highly effective; however, it is unclear if transfer patients derive similar benefit given the treatment delay intrinsic to this approach. Our aim was to determine the potential eligibility and efficacy of CT perfusion (CTP) guided IA therapy in transferred patients. Methods: All transferred and stent retriever treated ischemic stroke patients selected using CTP between 5/12 -1/15 were included. Baseline demographics including age, NIHSS, IV tPA use, and time points pertinent to CTP imaging and IA procedures were collected. Primary outcome was 90d mRS. Secondary endpoints included successful reperfusion and mortality. Primary safety endpoint was symptomatic ICH (sICH) rate. Results: Overall 401 transferred patients were potentially eligible and 22% were treated (n=90). Median age was 70 and median NIHSS 14.5 (SD 6.8). Average remote site distance was 90 (range 1- 356) miles. 73% received IV tPA. Median time of onset to reperfusion was 530 min. Median onset to CTP time was 323 min. Median CTP to groin puncture 138 min and median CTP time to reperfusion 197 min. TICI 2B or 3 reperfusion was achieved in 80%. 84 patients had 90d outcome data. Favorable outcome (mRS of 0-2) was achieved in 64%. sICH rate was 4.4%. 90d mortality was 11%. Conclusions: Outcomes in transferred CTP guided IA stroke therapy patients were similar to clinical trials despite onset to treatment times at least 80% longer than in recently reported studies, strongly supporting this approach. A substantial proportion of transfer patients can receive successful IA therapy using modern imaging techniques and treatments.

Background and Purpose: It remains unclear how experience influences outcomes after the advent of stent-retriever technology. We studied the relationship between site experience and outcomes in the TRevo ACute Ischemic StroKe (TRACK) multicenter registry. Methods: The 24 sites that enrolled patients in the TRACK registry were trichotomized into: low volume (enrolling 1-23 cases, less than 2 cases/ month), medium volume (24-47 cases, 2-4 cases/ month), and high volume sites (> 48 cases, > 4 cases/ month). Demographics, baseline features, and key prognostic presentation characteristics were compared across the three volume strata. Results: The 624 TRACK registry patients were divided into three sub groups: low (n=188 patients, 30.1%), medium (n=175, 28.1%), and high (n=261, 41.8%) volume centers. There were no significant differences in terms of age (mean, 66±16 vs. 67±14 vs. 65±15, p=0.2), baseline NIHSS (mean, 17.6±6.5 vs. 16.8±6.5 vs. 17.6±6.9, p=0.43) or site of occlusion across the 3 groups. Times from stroke onset to groin puncture were shorter in the medium volume sites (310 min) but similar in the low vs. high volumes sites (397 vs. 378 min). Higher efficiency and better outcomes were seen in higher volumes sites as demonstrated by faster times from groin puncture to reperfusion (mean, 89 vs. 82 vs. 65 min, p Conclusions: Clinical volumes have a significant influence in terms of efficiency and outcomes across stroke centers.

Background and Purpose— Acute ischemic stroke due to large vessel occlusion (LVO)—vertebral, basilar, carotid terminus, middle and anterior cerebral arteries—likely portends a worse prognosis than stroke unassociated with LVO. Because little prospective angiographic data have been reported on a cohort of unselected patients with stroke and with transient ischemic attack, the clinical impact of LVO has been difficult to quantify. Methods— The Screening Technology and Outcome Project in Stroke Study is a prospective imaging-based study of stroke outcomes performed at 2 academic medical centers. Patients with suspected acute stroke who presented within 24 hours of symptom onset and who underwent multimodality CT/CT angiography were approached for consent for collection of clinical data and 6-month assessment of outcome. Demographic and clinical variables and 6-month modified Rankin Scale scores were collected and combined with blinded interpretation of the CT angiography data. The OR of each variable, including occlusion of intracranial vascular segment in predicting good outcome and 6-month mortality, was calculated using univariate and multivariate logistic regression. Results— Over a 33-month period, 735 patients with suspected stroke were enrolled. Of these, 578 were adjudicated as stroke and 97 as transient ischemic attack. Among patients with stroke, 267 (46%) had LVO accounting for the stroke and 13 (13%) of patients with transient ischemic attack had LVO accounting for transient ischemic attack symptoms. LVO predicted 6-month mortality (OR, 4.5; 95% CI, 2.7 to 7.3; P P Conclusion— Large vessel intracranial occlusion accounted for nearly half of acute ischemic strokes in unselected patients presenting to academic medical centers. In addition to age and baseline stroke severity, occlusion of either the basilar or internal carotid terminus segment is an independent predictor of outcome at 6 months.

Background: Time to reperfusion following endovascular treatment (ET) strongly predicts outcomes after acute ischemic stroke (AIS). However, the impact of time may vary depending on the grade of reperfusion. We sought to assess time-outcome relationship within grades of reperfusion in the North American Solitaire Acute Stroke (NASA) registry. Methods: The investigator-initiated NASA registry recruited 24 clinical sites within North America to submit demographic, clinical, site-adjudicated angiographic, and clinical outcome data on consecutive patients treated with the Solitaire Flow Restoration device. We identified patients treated with anterior circulation ischemic stroke treated within 8 hours. The modified Thrombolysis in Cerebral Ischemia (TICI) was used wherein TICI 2 was divided in TICI 2a (< 50% reperfusion) and TICI 2b (> 50% reperfusion). We assessed the impact of time to reperfusion (onset to procedure completion time) on good outcome (modified Rankin Scale 0-2 at 3 months) in those who achieved at least TICI 2a reperfusion, independent of other relevant covariates using logistic regression analysis. We further assessed this relationship within strata of reperfusion grade. Results: Among 265 eligible patients, 209 (78.9%) had complete data (mean age 68.4 years, median NIHSS score 18). Reperfusion grade was as follows: TICI 3: 35.4%; TICI 2b: 39.7%, TICI 2a: 14.8%; TICI 0-1: 10.0%. Independent predictors of outcome at 3 months among those achieving TICI 2-3 reperfusion were: initial NIHSS score, intravenous tissue plasminogen activator use, symptomatic hemorrhage, and time to reperfusion. For each 30 minutes, the adjusted OR for time to reperfusion was 0.874 (95% CI 0.797-958). There was a significant interaction between final TICI grade and 30-minute time to reperfusion intervals (P=0.001) such that the effect of time was strongest in TICI 2a patients. Conclusions: Time to reperfusion is a strong predictor of outcome following ET for AIS with 13% decreased odds of good outcome per 30-minute delay in achieving TICI 2-3 reperfusion. However, the effect varied by TICI grade such that its greatest effect was in those achieving TICI 2a reperfusion.

Background and Purpose— Efficient and timely recanalization is an important goal in acute stroke endovascular therapy. Several studies demonstrated improved recanalization and clinical outcomes with the stent retriever devices compared with the Merci device. The goal of this study was to evaluate the role of the balloon guide catheter (BGC) and recanalization success in a substudy of the North American Solitaire Acute Stroke (NASA) registry. Methods— The investigator-initiated NASA registry recruited 24 clinical sites within North America to submit demographic, clinical, site-adjudicated angiographic, and clinical outcome data on consecutive patients treated with the Solitaire Flow Restoration device. BGC use was at the discretion of the treating physicians. Results— There were 354 patients included in the NASA registry. BGC data were reported in 338 of 354 patients in this subanalysis, of which 149 (44%) had placement of a BGC. Mean age was 67.3±15.2 years, and median National Institutes of Health Stroke Scale score was 18. Patients with BGC had more hypertension (82.4% versus 72.5%; P =0.05), atrial fibrillation (50.3% versus 32.8%; P =0.001), and were more commonly administered tissue plasminogen activator (51.6% versus 38.8%; P =0.02) compared with patients without BGC. Time from symptom onset to groin puncture and number of passes were similar between the 2 groups. Procedure time was shorter in patients with BGC (120±28.5 versus 161±35.6 minutes; P =0.02), and less adjunctive therapy was used in patients with BGC (20% versus 28.6%; P =0.05). Thrombolysis in cerebral infarction 3 reperfusion scores were higher in patients with BGC (53.7% versus 32.5%; P P =0.002) and good clinical outcome at 3 months were superior in patients with BGC compared with patients without (51.6% versus 35.8%; P =0.02). Multivariate analysis demonstrated that the use of BGC was an independent predictor of good clinical outcome (odds ratio, 2.5; 95% confidence interval, 1.2–4.9). Conclusions— Use of a BGC with the Solitaire Flow Restoration device resulted in superior revascularization results, faster procedure times, decreased need for adjunctive therapy, and improved clinical outcome.

Background and Purpose— Can lysability of large vessel thrombi in acute ischemic stroke be predicted by measuring clot density on admission nonenhanced CT (NECT), postcontrast enhanced CT, or CT angiogram (CTA)? Methods— We retrospectively studied 90 patients with acute large vessel ischemic strokes treated with intravenous (IV) tPA, intra-arterial (IA) tPA, and/or mechanical thrombectomy devices. Clot density [in Hounsfield unit (HU)] was measured on NECT, postcontrast enhanced CT, and CTA. Recanalization was assessed by the Thrombolysis in Cerebral Infarction grading system (TICI) on digital subtraction angiography. Results— Thrombus density on preintervention NECT correlated with postintervention TICI grade regardless of pharmacological (IV tPA r =0.69, IA tPA r =0.72, P r =0.73, P P =0.01, 0.006, Conclusions— Thrombi with lower HU on NECT appear to be more resistant to pharmacological lysis and mechanical thrombectomy. Measuring thrombus density on admission NECT provides a rapid method to analyze clot composition, a potentially useful discriminator in selecting the most appropriate reperfusion strategy for an individual patient.

Background: Thrombi in the setting of acute ischemic stroke have been classified in pathology studies as “red clots” (erythrocyte rich) versus “white clots” (platelet/fibrin rich). Current strategies in lysing these clots include pharmacological agents and mechanical devices. Despite these treatment options, thrombolysis fails in a significant portion of patients and may lead to hemorrhagic complications. Having insight into the clot composition may provide clinicians with a way to triage patients to the appropriate treatment. The purpose of the study was to investigate whether the lysability of thrombi in acute ischemic stroke can be predicted by measuring the Hounsfield (HU) on the admission non-contrast CT (NCT), post-contrast enhanced CT (CECT) and CTA. Methods: We studied 53 patients with acute anterior and posterior circulation large vessel ischemic strokes treated at our institution with IV tPA, IA tPA, and/or mechanical thrombectomy devices (Merci). The HU of the clot was measured on NCT, CECT and CTA. The HU of the homologous contralateral cerebral artery was also measured for standardization purposes. The obtained HU was corrected for hematocrit by using an accepted correction formula HUclot/HUcontralateral. The volume of the clot was calculated using the formula for a cylinder with an elliptical base (π x R x r xH). Recanalization was assessed by TICI grade (0-3). Results: There is a strong correlation between the HU of the thrombus on preintervention NCT and postintervention TICI grade among all patients regardless of pharmacological or mechanical treatment ( Table 1 ). Patients with TICI≥2 demonstrated higher HU on NCT compared to patients with TICI Conclusion: Thrombi with lower HU on NCT appear to be more resistant to pharmacological and mechanical thrombectomy and likely represent “white clots.” While thrombi with higher HU are less resistant to acute stroke therapies and likely represent “red clots.” Measuring the HU of the thrombus on the admission NCT provides the stroke team with a rapid method to analyze the clot composition, a potentially useful discriminator in selecting the most appropriate reperfusion strategy for an individual patient.

Background and Purpose— Digital subtraction angiography (DSA) is regarded as the gold standard in assessing degree of stenosis in intracranial vessels. However, it is invasive and can only be carried out at specialized centers. We sought to compare CT angiography (CTA) to DSA for detection and measurement of stenosis in large intracranial arteries. Methods— -We identified all subjects admitted with ischemic stroke or transient ischemic attack and with CTA and DSA studies of good quality completed within 30 days of each other between April 2000 and May 2006 at a single medical center. Two readers blinded to clinical information reviewed each CTA and DSA independently. Each reader located and measured stenosis of 15 prespecified large intracranial arterial segments per study at the same level of magnification. These stenotic lesions were most likely atherosclerotic in etiology. All measurements were made with Wiha digiMax 6“ digital calipers. The degree of stenosis was calculated using the published method for the Warfarin-Aspirin Symptomatic Intracranial Disease study. All disagreements of greater than 10% were reviewed by a third reader who decided between the 2 prior measurements. Segments were excluded from analyses if they were judged to be congenitally hypoplastic or seen only through collaterals or cross-filling. Intraclass correlation, sensitivity, and specificity were calculated using DSA as the reference standard. Results— Forty-one pairs of CTA and DSAs from 41 patients were reviewed. CTAs were completed within 28 days before 13 days after DSA, with a median of 1 day. A total of 475 pairs of major intracranial arterial segment were analyzed. Intraclass correlation between degree of stenosis based on CTA and DSA for all segments was 0.98 ( P =0.001). CTA detected large arterial occlusion with 100% sensitivity and specificity. For detection of ≥50% stenosis, CTA had 97.1% sensitivity and 99.5% specificity. To detect all lesions ≥50% as determined by DSA, the cut off point on CTA appeared to be at ≥30%, with a false-positive rate of 2.4%. Conclusions— Compared to DSA, CTA has high sensitivity and specificity for detecting ≥50% stenosis of large intracranial arterial segments. CTA is minimally invasive and may be a useful screening tool for intracranial arterial disease and occlusion.