Delayed Functional Independence After Neurothrombectomy (DEFIANT) score: analysis of the Trevo Retriever Registry

BACKGROUND

Chronological heterogeneity in neurological improvement after endovascular thrombectomy (EVT) for large vessel occlusion (LVO) stroke is commonly observed in clinical practice. Understanding the temporal progression of functional independence after EVT, especially delayed functional independence in patients who do not improve early, is essential for prognostication and rehabilitation. We aim to determine the incidence of early functional independence (EFI) and delayed functional independence (DFI), identify associated predictors after EVT, and develop the Delayed Functional Independence After Neurothrombectomy (DEFIANT) score.

METHODS

Demographic, clinical, radiological, treatment, and procedural information were analyzed from the Trevo Registry (patients undergoing EVT due to anterior LVO using the Trevo stent retriever). Incidence and predictors of EFI (modified Rankin Scale (mRS) score 0-2 at discharge) and DFI (mRS score 0-2 at 90 days in non-EFI patients) were analyzed.

RESULTS

A total of 1623 patients met study criteria. EFI was observed in 45% (730) of patients. Among surviving non-EFI patients (884), DFI was observed in 35% (308). Younger age (p=0.003), lower discharge National Institutes of Health Stroke Scale (NIHSS) score (p<0.0001), and absence of any hemorrhage (p=0.021) were independent predictors of DFI. After age 60, the probability of DFI declines significantly with 5 year age increments (approximately 7% decline for every 5 years; p(DFI)= 1.3559-0.0699, p for slope=0.001). The DEFIANT score is available online (https://bit.ly/3KZRVq5).

CONCLUSION

Approximately 45% of patients experience EFI. About one-third of non-early improvers experience DFI. Younger age, lower discharge NIHSS score, and absence of any hemorrhage were independent predictors of DFI among non-early improvers.

Endovascular Treatment Versus Best Medical Management in Acute Basilar Artery Occlusion Strokes: Results From the ATTENTION Multicenter Registry

BACKGROUND

The authors compare the effectiveness and safety of endovascular treatment (EVT) versus best medical management (BMM) in strokes attributable to acute basilar artery occlusion (BAO).

METHODS

The present analysis was based on the ongoing, prospective, multicenter ATTENTION (Endovascular Treatment for Acute Basilar Artery Occlusion) trial registry in China. Our analytic sample comprised 2134 patients recruited at 48 sites between 2017 and 2021 and included 462 patients who received BMM and 1672 patients who received EVT. We performed an inversed probability of treatment weighting analysis. Qualifying patients had to present within 24 hours of estimated BAO. The primary clinical outcome was favorable functional outcome (modified Rankin Scale score, 0-3) at 90 days. We also performed a sensitivity analysis with the propensity score matching-based and the instrumental variable-based analysis.

RESULTS

In our primary analysis using the inversed probability of treatment weighting-based analysis, there was a significantly higher rate of favorable outcome at 90 days among EVT patients compared with BMM-treated patients (adjusted relative risk, 1.42 [95% CI, 1.19-1.65]; absolute risk difference, 11.8% [95% CI, 6.9-16.7%]). The mortality was significantly lower (adjusted relative risk, 0.78 [95% CI, 0.69-0.88]; absolute risk difference, -10.3% [95% CI, -15.8 to -4.9]) in patients undergoing EVT. Results were generally consistent across the secondary end points. Similar associations were seen in the propensity score matching-based and instrumental variable-based analysis.

CONCLUSION

In this real-world study, EVT was associated with significantly better functional outcomes and survival at 90 days. Well-designed randomized studies comparing EVT with BMM in the acute BAO are needed.

REGISTRATION

URL: www.chictr.org.cn Unique identifier: ChiCTR2000041117.

Intravenous alteplase has different effects on the efficacy of aspiration and stent retriever thrombectomy: analysis of the COMPASS trial

BACKGROUND

There is conflicting evidence on the utility of intravenous (IV) alteplase in patients with emergent large vessel occlusion (ELVO) treated with mechanical thrombectomy (MT).

METHODS

This was a post hoc analysis of the COMPASS: a trial of aspiration thrombectomy versus stent retriever thrombectomy as first-line approach for large vessel occlusion. We compared clinical, procedural and angiographic outcomes of patients with and without prior IV alteplase administration.

RESULTS

In the COMPASS trial, 235 patients had presented to the hospital within the first 4 hours of stroke symptom onset and were eligible for analysis. On univariate analysis, administration of IV alteplase prior to MT was found to be significantly associated with favorable outcomes (modified Rankin scale (mRS) 0-2 at 3 months; 55.6% vs 40.0% in the MT-only group, P=0.037). However, on multivariate analysis, only baseline (pre-stroke) mRS, admission National Institutes of Health Stroke Scale (NIHSS) score and age were identified as independent predictors of favorable outcomes at 3 months. We found higher final thrombolysis in cerebral infarction (TICI) 2b/3 rates in patients without the use of alteplase prior to the aspiration first approach (100.0% vs 87.9% in IV altepase +aspiration first MT, P=0.03). In the stent retriever first group, final TICI 2b/3 rates were identical in patients with and without IV alteplase administration (87.5% and 87.5%, P=1.0).

CONCLUSIONS

Prior administration of IV alteplase may adversely affect the efficacy of aspiration, but does not seem to influence the stent retriever first approach to MT in patients with anterior circulation ELVO.

Abstract P467: Clinical Effectiveness of Endovascular Stroke Treatment in the Early and Extended Time Windows

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 <0.05 for all).

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.

POSITIVE: Perfusion imaging selection of ischemic stroke patients for endovascular therapy

BACKGROUND

The PerfusiOn imaging Selection of Ischemic sTroke patIents for endoVascular thErapy (POSITIVE) trial was designed to evaluate functional outcome in patients with emergent large vessel occlusion (ELVO) presenting within 0-12 hours with pre-specified bifurcated arms of early and late window presentation, who were selected for endovascular thrombectomy with non-vendor specific commercially available perfusion imaging software. Recent trials demonstrating the benefit of thrombectomy up to 16-24 hours following ELVO removed equipoise to randomize late window ELVO patients and therefore the trial was halted.

METHODS

Up to 200 patients were to be enrolled in this FDA-cleared, prospective, randomized, multicenter international trial to compare thrombectomy and best medical management in patients with ELVO ineligible for or refractory to treatment with IV tissue plasminogen activator (IV-tPA) selected with perfusion imaging and presenting within 0-12 hours of last seen normal. The primary outcome was 90-day clinical outcome as measured by the raw modified Rankin Scale (mRS) with scores 5 and 6 collapsed (mRS shift analysis).

RESULTS

The POSITIVE trial suspended enrollment with the release of results from the DAWN trial and was stopped after the release of the DEFUSE 3 trial results. Thirty-three patients were enrolled (21 for medical management and 12 for thrombectomy). Twelve of the 33 patients were enrolled in the 6-12 hour cohort. Despite the early cessation, the primary outcome demonstrated statistically significant superior clinical outcomes for patients treated with thrombectomy (P=0.0060). The overall proportion of patients achieving an mRS score of 0-2 was 75% in the thrombectomy cohort and 43% in the medical management cohort (OR 4.00, 95% CI 0.84 to 19.2).

CONCLUSION

POSITIVE supports the already established practice of delayed thrombectomy for appropriately selected patients presenting within 0-12 hours selected by perfusion imaging from any vendor. The results of the POSITIVE trial are consistent with other thrombectomy trials. The statistically significant effect on functional improvement, despite the small number of patients, reinforces the robust benefits of thrombectomy.

CLINICAL TRIAL REGISTRATION

NCT01852201.

Endovascular therapy in the distal neurovascular territory: results of a large prospective registry

BACKGROUND

There is a paucity of data regarding mechanical thrombectomy (MT) in distal arterial occlusions (DAO). We aim to evaluate the safety and efficacy of MT in patients with DAO and compare their outcomes with proximal arterial occlusion (PAO) strokes.

METHODS

The Trevo Registry was a prospective open-label MT registry including 2008 patients from 76 sites across 12 countries. Patients were categorized into: PAO: intracranial ICA, and MCA-M1; and DAO: MCA-M2, MCA-M3, ACA, and PCA. Baseline and outcome variables were compared across the PAO vs DAO patients with pre-morbid mRS 0-2.

RESULTS

Among 407 DAOs including 350 (86.0%) M2, 25 (6.1%) M3, 10 (2.5%) ACA, and 22 (5.4%) PCA occlusions, there were 376 DAO with pre-morbid mRS 0-2 which were compared with 1268 PAO patients. The median baseline NIHSS score was lower in DAO (13 [8-18] vs 16 [12-20], P<0.001). There were no differences in terms of age, sex, IV-tPA use, co-morbidities, or time to treatment across DAO vs PAO. The rates of post-procedure reperfusion, symptomatic intracranial hemorrhage (sICH), and 90-mortality were comparable between both groups. DAO showed significantly higher rates of 90-day mRS 0-2 (68.3% vs 56.5%, P<0.001). After adjustment for potential confounders, the level of arterial occlusion was not associated with the chances of excellent outcome (DAO for 90-day mRS 0-1: OR; 1.18, 95% CI [0.90 to 1.54], P=0.225), successful reperfusion or SICH. However, DAO patients were more likely to be functionally independent (mRS 0-2: OR; 1.45, 95% CI [1,09 to 1.92], P=0.01) or dead (OR; 1.54, 95% CI [1.06 to 2.27], P=0.02) at 90 days.

CONCLUSION

Endovascular therapy in DAO appears to result in a comparable safety and technical success profile as in PAO. The potential benefits of DAO thrombectomy should be investigated in future randomized trials.

Clot perviousness is associated with first pass success of aspiration thrombectomy in the COMPASS trial

BACKGROUND

Clot density (Hounsfield units, HU) and perviousness (post-contrast increase in the HU of clot) are thought to be associated with clot composition. We evaluate whether these imaging characteristics were associated with angiographic outcomes of aspiration and stent retriever thrombectomy in COMPASS: a trial of aspiration thrombectomy versus stent retriever thrombectomy as first-line approach for large vessel occlusion.

METHODS

Clot density and perviousness were measured by two independent operators who were blind to all the final angiographic and clinical outcomes. The association of clot density and perviousness with the Thrombolysis In Cerebral Infarction (TICI) scale after first pass was assessed using univariate and multivariate analysis.

RESULTS

Among all patients enrolled in COMPASS, 165 were eligible for the post-hoc analysis (81 patients in the aspiration first and 84 in the stent retriever first groups). Overall mean perviousness of clot was significantly higher in patient with mTICI 2b-3 after first pass (28.6±22.9 vs 20.3±19.2, p=0.017). Mean perviousness among patients who achieved TICI 2c/3 versus TICI 2b versus TICI 0-2a in the aspiration first group varied significantly (32.6±26.1, 35.3±24.4, and 17.7±13.1, p=0.013). The association of perviousness with first pass success was not significant in the stent retriever group. Using multivariate analysis, high perviousness (defined as cut-off >27.6) was an independent predictor of TICI 2b-3 (OR 3.82, 95% CI 1.10 to 13.19; p=0.034).

CONCLUSIONS

Clot perviousness is associated with first pass angiographic success in patients treated with the aspiration first approach for thrombectomy.

The WOVEN trial: Wingspan One-year Vascular Events and Neurologic Outcomes

BACKGROUND

Prior studies evaluating the Wingspan stent for treatment of symptomatic intracranial atherosclerotic disease have included patients with a spectrum of both on-label and off-label indications for the stent. The WEAVE trial assessed 152 patients stented with the Wingspan stent strictly by its current on-label indication and found a 2.6% periprocedural stroke and death rate.

OBJECTIVE

This WOVEN study assesses the 1-year follow-up from this cohort.

METHODS

Twelve of the original 24 sites enrolling patients in the WEAVE trial performed follow-up chart review and imaging analysis up to 1 year after stenting. Assessment of delayed stroke and death was made in 129 patients, as well as vascular imaging follow-up to assess for in-stent re-stenosis.

RESULTS

In the 1-year follow-up period, seven patients had a stroke (six minor, one major). Subsequent to the periprocedural period, no deaths were recorded in the cohort. Including the four patients who had periprocedural events in the WEAVE study, there were 11 strokes or deaths of the 129 patients (8.5%) at the 1-year follow-up.

CONCLUSIONS

The WOVEN study provides the 1-year follow-up on a cohort of 129 patients who were stented according to the current on-label use. It provides a more homogeneous patient group for analysis than prior studies, and demonstrates a relatively low 8.5% 1-year stroke and death rate in stented patients.

Discrepancy between post-treatment infarct volume and 90-day outcome in the ESCAPE randomized controlled trial

BACKGROUND

Some patients with ischemic stroke have poor outcomes despite small infarcts after endovascular thrombectomy, while others with large infarcts sometimes fare better.

AIMS

We explored factors associated with such discrepancies between post-treatment infarct volume (PIV) and functional outcome.

METHODS

We identified patients with small PIV (volume ≤ 25th percentile) and large PIV (volume ≥ 75th percentile) on 24-48-h CT/MRI in the ESCAPE randomized-controlled trial. Demographics, comorbidities, baseline, and 24-48-h stroke severity (NIHSS), stroke location, treatment type, post-stroke complications, and other outcome scales like Barthel Index, and EQ-5D were compared between "discrepant cases" - those with 90-day modified Rankin Scale(mRS) ≤ 2 despite large PIV or mRS ≥ 3 despite small PIV - and "non-discrepant cases". Multi-variable logistic regression was used to identify pre-treatment and post-treatment factors associated with small-PIV/mRS ≥ 3 and large-PIV/mRS ≤ 2. Sensitivity analyses used different definitions of small/large PIV and good/poor outcome.

RESULTS

Among 315 patients, median PIV was 21 mL; 27/79 (34.2%) patients with PIV ≤ 7 mL (25th percentile) had mRS ≥ 3; 12/80 (15.0%) with PIV ≥ 72 mL (75th percentile) had mRS ≤ 2. Discrepant cases did not differ by CT versus MRI-based PIV ascertainment, or right versus left-hemisphere involvement (p = 0.39, p = 0.81, respectively, for PIV ≤ 7 mL/mRS ≥ 3). Pre-treatment factors independently associated with small-PIV/mRS ≥ 3 included older age (p = 0.010), cancer, and vascular risk-factors; post-treatment factors included 48-h NIHSS (p = 0.007) and post-stroke complications (p = 0.026). Absence of vascular risk-factors (p = 0.004), CT-based lentiform nucleus sparing (p = 0.002), lower 24-hour NIHSS (p = 0.001), and absence of complications (p = 0.013) were associated with large-PIV/mRS ≤ 2. Sensitivity analyses yielded similar results.

CONCLUSIONS

Discrepancies between functional ability and PIV are likely explained by differences in age, comorbidities, and post-stroke complications, emphasizing the need for high-quality post-thrombectomy stroke care.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT01778335.

Influence of thrombectomy volume on non-physician staff burnout and attrition in neurointerventional teams

BACKGROUND

Burnout takes a heavy toll on healthcare providers. We sought to assess the prevalence and risk factors for burnout among neurointerventional (NI) non-physician procedural staff (nurses and technologists) given increasing thrombectomy demands.

METHODS

A 41-question online survey containing questions including the Maslach Burnout Inventory-Human Services Survey for Medical Personnel was distributed to NI nurses and radiology technologists at 20 US endovascular capable stroke centers.

RESULTS

244 responses were received (64% response rate). Median (IQR) composite scores for emotional exhaustion were 25 (15-35), depersonalization 6 (2-11), and personal accomplishment 39 (35-43). Fifty-one percent of respondents met established criteria for burnout. There was no significant relationship between hospital thrombectomy volume, call frequency, call cases covered, or length of commute. On multiple logistic regression analysis, feeling under-appreciated by hospital leadership (OR 4.1; P<0.001) and working with difficult/unpleasant physicians (OR 1.2; P=0.05) were strongly associated with burnout. At participating centers, nurse and technologist attrition was 25% over the previous year. Over 50% of respondents indicated they had strongly considered leaving their position over the last 2 years.

CONCLUSIONS

This survey of US NI non-physician procedural staff demonstrates a self-reported burnout prevalence of 51%. This was driven more by interaction with leadership and physician staff than by thrombectomy procedural volume and stroke call. Attrition among NI non-physician procedural staff is high.

Endovascular treatment decision in acute stroke: does physician gender matter? Insights from UNMASK EVT, an international, multidisciplinary survey

Background and purpose

Differences in the treatment practice of female and male physicians have been shown in several medical subspecialties. It is currently not known whether this also applies to endovascular stroke treatment. The purpose of this study was to explore whether there are differences in endovascular treatment decisions made by female and male stroke physicians and neurointerventionalists.

Methods

In an international survey, stroke physicians and neurointerventionalists were randomly assigned 10 case scenarios and asked how they would treat the patient: (A) assuming there were no external constraints and (B) given their local working conditions. Descriptive statistics were used to describe baseline demographics, and the adjusted OR for physician gender as a predictor of endovascular treatment decision was calculated using logistic regression.

Results

607 physicians (97 women, 508 men, 2 who did not wish to declare) participated in this survey. Physician gender was neither a significant predictor for endovascular treatment decision under assumed ideal conditions (endovascular therapy was favored by 77.0% of female and 79.3% of male physicians, adjusted OR 1.03, P=0.806) nor under current local resources (endovascular therapy was favored by 69.1% of female and 76.9% of male physicians, adjusted OR 1.03, P=0.814).

Conclusion

Endovascular therapy decision making between male and female physicians did not differ under assumed ideal conditions or under current local resources.

Time of day and endovascular treatment decision in acute stroke with relative endovascular treatment indication: insights from UNMASK EVT international survey

Background and purpose

The decision to proceed with endovascular thrombectomy should ideally be made independent of inconvenience factors, such as daytime. We assessed the influence of patient presentation time on endovascular therapy decision making under current local resources and assumed ideal conditions in acute ischemic stroke with level 2B evidence for endovascular treatment.

Methods and materials

In an international cross sectional survey, 607 stroke physicians from 38 countries were asked to give their treatment decisions to 10 out of 22 randomly assigned case scenarios. Eleven scenarios had level 2B evidence for endovascular treatment: 7 daytime scenarios (7:00 am–5:00 pm) and four night time cases (5:01 pm– 6:59 am). Participants provided their treatment approach assuming (A) there were no practice constraints and (B) under their current local resources. Endovascular treatment decisions in the 11 scenarios were analyzed according to presentation time with adjustment for patient and physician characteristics.

Results

Participants selected endovascular therapy in 74.2% under assumed ideal conditions, and 70.7% under their current local resources of night time scenarios, and in 67.2% and 63.8% of daytime scenarios. Night time presentation did not increase the probability of a treatment decision against endovascular therapy under current local resources or assumed ideal conditions.

Conclusion

Presentation time did not influence endovascular treatment decision making in stroke patients in this international survey.

Abstract WP111: Who Needs Neuroprotection With Endovascular Stroke Therapy? Findings From the Trevo Retriever Registry

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=<0.02) as a factor, adjusting for withdrawal of care. Expectedly, greater baseline NIHSS severity predicted greater day 90 disability (OR 1.07-1.08, all p<0.001). TLSW was a predictor only with eTICI ≥ 2b50 (per hour, OR 1.02, p=0.039). History of diabetes was a factor only with eTICI ≥ 2b50 and eTICI ≥ 2b67 (OR 2.05-2.19, p<0.001). Worse collateral grade (ASITN 0-1) was the most potent predictor (OR 2.27-2.71 versus ASITN 2, p=0.027-0.052; OR 3.85-4.35 versus ASITN 3-4, all p=0.003).

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.

Abstract WMP4: Fast versus Slow Progressors in Real-World Data From the Trevo Retriever Registry: Collaterals Dominate Time to Reperfusion in Clinical Outcome After Thrombectomy

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<0.001) and better probability of functional independence (aOR 1.4, 95% CI 1.2, 1.7) per grade of collateral flow.

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.

Imaging of Patients with Suspected Large-Vessel Occlusion at Primary Stroke Centers: Available Modalities and a Suggested Approach

The overwhelming benefit of endovascular therapy in patients with large-vessel occlusions suggests that more patients will be screened than treated. Some of those patients will be evaluated first at primary stroke centers; this type of evaluation calls for standardizing the imaging approach to minimize delays in assessing, transferring, and treating these patients. Here, we propose that CT angiography (performed at the same time as head CT) should be the minimum imaging approach for all patients with stroke with suspected large-vessel occlusion presenting to primary stroke centers. We discuss some of the implications of this approach and how to facilitate them.

Treatment of blood blister aneurysms of the internal carotid artery with flow diversion

Background

Blood blister aneurysms (BBA) are a rare subset of intracranial aneurysms that represent a therapeutic challenge from both a surgical and endovascular perspective.

Objective

To report multicenter experience with flow diversion exclusively for BBA, located at non-branching segments along the anteromedial wall of the supraclinoidal internal carotid artery (ICA).

Methods

Consecutive cases of BBA located at non-branching segments along the anteromedial wall of the supraclinoidal ICA treated with flow diversion were included in the final analysis.

Results

49 patients with 51 BBA of the ICA treated with devices to achieve the flow diversion effect were identified. 43 patients with 45 BBA of the ICA were treated with the pipeline embolization device and were included in the final analysis. Angiographic follow-up data were available for 30 patients (32 aneurysms in total); 87.5% of aneurysms (28/32) showed complete obliteration, 9.4% (3/32) showed reduced filling, and 3.1% (1/32) persistent filling. There was no difference between the size of aneurysm (≤2 mm vs >2 mm) or the use of adjunct coiling and complete occlusion of the aneurysm on follow-up (P=0.354 and P=0.865, respectively). Clinical follow-up data were available for 38 of 43 patients. 68% of patients (26/38) had a good clinical outcome (modified Rankin scale score of 0–2) at 3 months. There were 7 (16%) immediate procedural and 2 (5%) delayed complications, with 1 case of fatal delayed re-rupture after the initial treatment.

Conclusions

Our data support the use of a flow diversion technique as a safe and effective therapeutic modality for BBA of the supraclinoid ICA.

Abstract 63: Collaterals in Thrombectomy for MCA Occlusion: Mapping the Collaterome in the Trevo Retriever Registry

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, p<0.001) with more modest correlation between collateral grade and CTP/DWI (rrCBF<30% or ADC<620) infarct core (r=-0.31, n=391; p<0.001) or CTP/PWI (Tmax>6s) 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.

Abstract 114: Aspects versus Perfusion in the Trevo Retriever Registry: Defining the Core on the Largest Scale to Date

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<30% (CTP) and analyzed with respect to ASPECTS.

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<0.001) yet no time relationship was noted with either ischemic core or at-risk hypoperfusion on perfusion imaging. ASPECTS correlated modestly with perfusion imaging-derived ischemic core (r=-0.35, p<0.001) and at-risk hypoperfusion (r=-0.24, p<0.001). Post-procedure mTICI≥2b occurred in 448/488 (91.8%). Each increment in baseline ASPECTS was associated with an adjusted OR of 1.21 (95%CI (1.05-1.39), p<0.008 for good clinical outcomes (day 90 mRS 0-2), whereas the perfusion lesion volume for ischemic core and at-risk hypoperfusion did not predict outcomes.

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.

Thrombectomy 6 to 24 Hours after Stroke with a Mismatch between Deficit and Infarct

BACKGROUND

The effect of endovascular thrombectomy that is performed more than 6 hours after the onset of ischemic stroke is uncertain. Patients with a clinical deficit that is disproportionately severe relative to the infarct volume may benefit from late thrombectomy.

METHODS

We enrolled patients with occlusion of the intracranial internal carotid artery or proximal middle cerebral artery who had last been known to be well 6 to 24 hours earlier and who had a mismatch between the severity of the clinical deficit and the infarct volume, with mismatch criteria defined according to age (<80 years or ≥80 years). Patients were randomly assigned to thrombectomy plus standard care (the thrombectomy group) or to standard care alone (the control group). The coprimary end points were the mean score for disability on the utility-weighted modified Rankin scale (which ranges from 0 [death] to 10 [no symptoms or disability]) and the rate of functional independence (a score of 0, 1, or 2 on the modified Rankin scale, which ranges from 0 to 6, with higher scores indicating more severe disability) at 90 days.

RESULTS

A total of 206 patients were enrolled; 107 were assigned to the thrombectomy group and 99 to the control group. At 31 months, enrollment in the trial was stopped because of the results of a prespecified interim analysis. The mean score on the utility-weighted modified Rankin scale at 90 days was 5.5 in the thrombectomy group as compared with 3.4 in the control group (adjusted difference [Bayesian analysis], 2.0 points; 95% credible interval, 1.1 to 3.0; posterior probability of superiority, >0.999), and the rate of functional independence at 90 days was 49% in the thrombectomy group as compared with 13% in the control group (adjusted difference, 33 percentage points; 95% credible interval, 24 to 44; posterior probability of superiority, >0.999). The rate of symptomatic intracranial hemorrhage did not differ significantly between the two groups (6% in the thrombectomy group and 3% in the control group, P=0.50), nor did 90-day mortality (19% and 18%, respectively; P=1.00).

CONCLUSIONS

Among patients with acute stroke who had last been known to be well 6 to 24 hours earlier and who had a mismatch between clinical deficit and infarct, outcomes for disability at 90 days were better with thrombectomy plus standard care than with standard care alone. (Funded by Stryker Neurovascular; DAWN ClinicalTrials.gov number, NCT02142283 .).

Time for a Time Window Extension: Insights from Late Presenters in the ESCAPE Trial

BACKGROUND AND PURPOSE

The safety and efficacy of endovascular therapy for large-artery stroke in the extended time window is not yet well-established. We performed a subgroup analysis on subjects enrolled within an extended time window in the Endovascular Treatment for Small Core and Proximal Occlusion Ischemic Stroke (ESCAPE) trial.

MATERIALS AND METHODS

Fifty-nine of 315 subjects (33 in the intervention group and 26 in the control group) were randomized in the ESCAPE trial between 5.5 and 12 hours after last seen healthy (likely to have groin puncture administered 6 hours after that). Treatment effect sizes for all relevant outcomes (90-day mRS shift, mRS 0-2, mRS 0-1, and 24-hour NIHSS scores and intracerebral hemorrhage) were reported using unadjusted and adjusted analyses.

RESULTS

There was no evidence of treatment heterogeneity between subjects in the early and late windows. Treatment effect favoring intervention was seen across all clinical outcomes in the extended time window (absolute risk difference of 19.3% for mRS 0-2 at 90 days). There were more asymptomatic intracerebral hemorrhage events within the intervention arm (48.5% versus 11.5%, P = .004) but no difference in symptomatic intracerebral hemorrhage.

CONCLUSIONS

Patients with an extended time window could potentially benefit from endovascular treatment. Ongoing randomized controlled trials using imaging to identify late presenters with favorable brain physiology will help cement the paradigm of using time windows to select the population for acute imaging and imaging to select individual patients for therapy.

Correlation between Clinical Outcomes and Baseline CT and CT Angiographic Findings in the SWIFT PRIME Trial

BACKGROUND AND PURPOSE

Patient selection for endovascular therapy remains a great challenge in clinic practice. We sought to determine the effect of baseline CT and angiography on outcomes in the Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment for Acute Ischemic Stroke (SWIFT PRIME) trial and to identify patients who would benefit from endovascular stroke therapy.

MATERIALS AND METHODS

The primary end point was a 90-day modified Rankin Scale score of 0-2. Subgroup and classification and regression tree analysis was performed on baseline ASPECTS, site of occlusion, clot length, collateral status, and onset-to-treatment time.

RESULTS

Smaller baseline infarct (n = 145) (ASPECTS 8-10) was associated with better outcomes in patients treated with thrombectomy versus IV tPA alone (66% versus 41%; rate ratio, 1.62) compared with patients with larger baseline infarcts (n = 44) (ASPECTS 6-7) (42% versus 21%; rate ratio, 1.98). The benefit of thrombectomy over IV tPA alone did not differ significantly by ASPECTS. Stratification by occlusion location also showed benefit with thrombectomy across all groups. Improved outcomes after thrombectomy occurred in patients with clot lengths of ≥8 mm (71% versus 43%; rate ratio, 1.67). Outcomes stratified by collateral status had a benefit with thrombectomy across all groups: none-fair collaterals (33% versus 0%), good collaterals (58% versus 44%), and excellent collaterals (82% versus 28%). Using a 3-level classification and regression tree analysis, we observed optimal outcomes in patients with favorable baseline ASPECTS, complete/near-complete recanalization (TICI 2b/3), and early treatment (mean mRS, 1.35 versus 3.73), while univariate and multivariate logistic regression showed significantly better results in patients with higher ASPECTS.

CONCLUSIONS

While benefit was seen with endovascular therapy across multiple subgroups, the greatest response was observed in patients with a small baseline core infarct, excellent collaterals, and early treatment.

Acute ischemic stroke with tandem lesions: technical endovascular management and clinical outcomes from the ESCAPE trial

Background

Tandem occlusions of the extracranial carotid and intracranial carotid or middle cerebral artery have a particularly poor prognosis without treatment. Several management strategies have been used with no clear consensus recommendations. We examined subjects with tandem occlusions enrolled in the ESCAPE trial and their outcomes.

Methods

Data are from the ESCAPE trial. Additional data were sought on interventions for each subject.

Results

There were 54 (17%) subjects with tandem extracranial and intracranial occlusions. Patients in the endovascular treatment arm (n=30) were more likely to be younger (median age 66 years, p<0.01), male (66.7%, p=0.03), diabetic, and without atrial fibrillation. Subjects with tandem occlusions were more likely to have intracranial internal carotid artery occlusions than M1 occlusions (p<0.01). Of the 30 intervention-arm subjects, 17 (57%) underwent emergency endovascular treatment of the extracranial disease, 10 subjects before and seven subjects after intracranial thrombectomy. Of the remaining 13 subjects, only four required staged carotid revascularization due to persistent severe carotid stenosis; four had cervical pseudo-occlusions with no residual stenosis after large distal carotid thrombus burden aspiration/retrieval. Outcomes were similar between subjects with and without tandem lesions. The use of antithrombotic agents after acute carotid artery stenting was variable but no symptomatic intracerebral hemorrhage was seen in subjects who underwent emergency endovascular treatment of extracranial carotid artery.

Conclusions

Tandem occlusions occurred in one-sixth of patients and were treated highly variably within the ESCAPE trial. While outcomes were similar, the best method to treat the carotid artery in patients with tandem occlusion awaits further randomized data.

Trial registration number

NCT01778335.

Interhospital Transfer Before Thrombectomy Is Associated With Delayed Treatment and Worse Outcome in the STRATIS Registry (Systematic Evaluation of Patients Treated With Neurothrombectomy Devices for Acute Ischemic Stroke)

Supplemental Digital Content is available in the text.

Background:

Endovascular treatment with mechanical thrombectomy (MT) is beneficial for patients with acute stroke suffering a large-vessel occlusion, although treatment efficacy is highly time-dependent. We hypothesized that interhospital transfer to endovascular-capable centers would result in treatment delays and worse clinical outcomes compared with direct presentation.

Methods:

STRATIS (Systematic Evaluation of Patients Treated With Neurothrombectomy Devices for Acute Ischemic Stroke) was a prospective, multicenter, observational, single-arm study of real-world MT for acute stroke because of anterior-circulation large-vessel occlusion performed at 55 sites over 2 years, including 1000 patients with severe stroke and treated within 8 hours. Patients underwent MT with or without intravenous tissue plasminogen activator and were admitted to endovascular-capable centers via either interhospital transfer or direct presentation. The primary clinical outcome was functional independence (modified Rankin Score 0–2) at 90 days. We assessed (1) real-world time metrics of stroke care delivery, (2) outcome differences between direct and transfer patients undergoing MT, and (3) the potential impact of local hospital bypass.

Results:

A total of 984 patients were analyzed. Median onset-to-revascularization time was 202.0 minutes for direct versus 311.5 minutes for transfer patients (P<0.001). Clinical outcomes were better in the direct group, with 60.0% (299/498) achieving functional independence compared with 52.2% (213/408) in the transfer group (odds ratio, 1.38; 95% confidence interval, 1.06–1.79; P=0.02). Likewise, excellent outcome (modified Rankin Score 0–1) was achieved in 47.4% (236/498) of direct patients versus 38.0% (155/408) of transfer patients (odds ratio, 1.47; 95% confidence interval, 1.13–1.92; P=0.005). Mortality did not differ between the 2 groups (15.1% for direct, 13.7% for transfer; P=0.55). Intravenous tissue plasminogen activator did not impact outcomes. Hypothetical bypass modeling for all transferred patients suggested that intravenous tissue plasminogen activator would be delayed by 12 minutes, but MT would be performed 91 minutes sooner if patients were routed directly to endovascular-capable centers. If bypass is limited to a 20-mile radius from onset, then intravenous tissue plasminogen activator would be delayed by 7 minutes and MT performed 94 minutes earlier.

Conclusions:

In this large, real-world study, interhospital transfer was associated with significant treatment delays and lower chance of good outcome. Strategies to facilitate more rapid identification of large-vessel occlusion and direct routing to endovascular-capable centers for patients with severe stroke may improve outcomes.

Clinical Trial Registration:

URL: https://www.clinicaltrials.gov. Unique identifier: NCT02239640.

Abstract WP5: The Transfer Score May Aid Decisions Whether to Transfer Patients with Large Vessel Occlusions for Endovascular Therapy

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 <0.001). These results were maintained after adjustment for mTICI and IV-tPA (aOR 4.0, 95% CI 1.7-9.4; p <0.001). Fig 1 shows good outcome rates stratified by score points. ROC curves showed better score performance (AUC= 0.8) compared to THRIVE (AUC=0.74) and HIAT (AUC=0.69) certifying good predictability.

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.

Abstract WMP2: Trevo 2000: Real-World Experience in the First 1247 Patients

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.

Abstract WMP9: Endovascular Thrombectomy Impact in the First Three “Golden” Hours

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 <0.001) after adjustment for age, NIHSS, IV tPA and mTICI ≥2b (Table 2). No differences were found in mortality and sICH. Treatment in the golden hours had the highest impact on excellent outcome rates (mRS 0-1) (Fig 1).

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.

Abstract TP20: Uncertainties of Endovascular Therapy Outside the AHA Guidelines

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, age ≥80 yo, NIHSS <6, onset to treatment >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 <6 and 81.5% of those achieved a good outcome (aOR 3.6, 95% CI 1.9-6.8; 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 <0.001 compared with <80 yo). Among 212 patients treated >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 (3-5) had a good outcome. Fig 1 illustrates mRS distributions stratified by the different subgroups. There were low rates of sICH for treated patients with NIHSS<6, age≥80, ASPECTS <6 or treatment >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.

Abstract WMP11: Joint Commission Certified Stroke Centers Treat More Severe Strokes with Faster Procedure Times Compared to Non-joint Commission Certified Stroke Centers in the Trevo Registry

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<0.02). There were no differences in outcomes, reperfusion rates or symptomatic hemorrhage rates between the two groups. Demographics were similar except patients treated at a JCCSC had a higher median NIHSS [17 vs. 15, p<0.003] compared to the non-JCCSC group. Median (IQR) door to puncture times did not differ between the two groups [85(57-132) vs. 91(59-137), p<0.96], but patients treated at a JCCSC had lower mean angiographic procedure times [59 ± 34 minutes vs. 66±44 minutes, p<0.05]. The analysis did not change when we looked at the subset of patients who were not transferred with anterior circulation strokes less than 8 hours from onset.

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.

Abstract 37: ASPECTS and Stratified Outcomes After Endovascular Therapy in the Trevo Retriever Registry: Benefit in Low ASPECTS

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<0.001). Subsequent symptomatic ICH was 1.7% with baseline ASPECTS 0-7 versus 2.0% with ASPECTS 8-10. The distribution of mRS at 90 days based on individual ASPECTS strata from 10 to 3 revealed a trend to worse outcomes with lower ASPECTS, yet good outcomes (mRS 0-2) were 60.7% (ASPECTS 10), 55.3% (9), 60.2% (8), 54.9% (7), 55.1% (3-6).

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.

Abstract WP6: Real-World Data on Reperfusion: Evidence of Good Outcomes in the International Trevo Retriever Registry

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.

Abstract WP4: Transfer Patients and Patients Presenting Directly to Endovascular Capable Centers Achieve Similar Good Outcome Rates with Endovascular Therapy

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 <0.001) (Table 1). DIR achieved higher excellent outcomes (50.4 vs 38.7%; p <0.001) (Table 2). There were no significant differences in good clinical outcomes (61 DIR vs 57.4% TNS, OR 0.90, 95% CI 0.63-1.27; 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 <5 hrs (OR 1.6) were independent predictors of good outcome in TNS patients.

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.

Infarct in a New Territory After Treatment Administration in the ESCAPE Randomized Controlled Trial (Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion With Emphasis on Minimizing CT to Recanalization Times)

Background and Purpose—

Infarct in a new previously unaffected territory (INT) is a potential complication of endovascular treatment. We applied a recently proposed methodology to identify and classify INTs in the ESCAPE randomized controlled trial (Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion With Emphasis on Minimizing CT to Recanalization Times).

Methods—

The core laboratory identified INTs on 24-hour follow-up imaging, blinded to treatment allocation, after assessing all baseline imaging. INTs were classified into 3 types (I–III) and 2 subtypes (A/B) based on size and if catheter manipulation was likely performed across the vessel territory ostium. Logistic regression was used to understand the effect of multiple a priori identified variables on INT occurrence. Ordinal logistic regression was used to analyze the effect of INTs on modified Rankin Scale shift at 90 days.

Results—

From 308 patients included, 14 INTs (4.5% overall; 2.8% on follow-up noncontrast computed tomography, 11.7% on follow-up magnetic resonance imaging) were identified (5.0% in endovascular treatment arm versus 4.0% in control arm [ P =0.7]). The use of intravenous alteplase was associated with a 68% reduction in the odds of INT occurrence (3.0% with versus 9.1% without; odds ratio, 0.32; 95% confidence interval, 0.11–0.96; adjusted for age, sex, and treatment type). No other variables were associated with INTs. INT occurrence was associated with reduced probability of good clinical outcome (common odds ratio, 0.25; 95% confidence interval, 0.09–0.74; adjusted for age, type of treatment, and follow-up scan).

Conclusions—

INTs are uncommon, detected more frequently on follow-up magnetic resonance imaging, and affect clinical outcome. In experienced centers, endovascular treatment is likely not causal, whereas intravenous alteplase may be therapeutic.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT01778335.

Intra-Arterial Therapy and Post-Treatment Infarct Volumes: Insights From the ESCAPE Randomized Controlled Trial

BACKGROUND AND PURPOSE

The goal of reperfusion therapy in acute ischemic stroke is to limit brain infarction. The objective of this study was to investigate whether the beneficial effect of endovascular treatment on functional outcome could be explained by a reduction in post-treatment infarct volume.

METHODS

The Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion With Emphasis on Minimizing CT to Recanalization Times (ESCAPE) trial was a multicenter randomized open-label trial with blinded outcome evaluation. Among 315 enrolled subjects (endovascular treatment n=165; control n=150), 314 subject's infarct volumes at 24 to 48 hours on magnetic resonance imaging (n=254) or computed tomography (n=60) were measured. Post-treatment infarct volumes were compared by treatment assignment and recanalization/reperfusion status. Appropriate statistical models were used to assess relationship between baseline clinical and imaging variables, post-treatment infarct volume, and functional status at 90 days (modified Rankin Scale).

RESULTS

Median post-treatment infarct volume in all subjects was 21 mL (interquartile range =65 mL), in the intervention arm, 15.5 mL (interquartile range =41.5 mL), and in the control arm, 33.5 mL (interquartile range =84 mL; P<0.01). Baseline National Institute of Health Stroke Scale (P<0.01), site of occlusion (P<0.01), baseline noncontrast computed tomographic scan Alberta Stroke Program Early CT score (ASPECTS) (P<0.01), and recanalization (P<0.01) were independently associated with post-treatment infarct volume, whereas age, sex, treatment type, intravenous alteplase, and time from onset to randomization were not (P>0.05). Post-treatment infarct volume (P<0.01) and delta National Institute of Health Stroke Scale (P<0.01) were independently associated with 90-day modified Rankin Scale, whereas laterality (left versus right) was not.

CONCLUSIONS

These results support the primary results of the ESCAPE trial and show that the biological underpinning of the success of endovascular therapy is a reduction in infarct volume.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01778335.

Clinical and Procedural Predictors of Outcomes From the Endovascular Treatment of Posterior Circulation Strokes

Background and Purpose—

Patients with posterior circulation strokes have been excluded from recent randomized endovascular stroke trials. We reviewed the recent multicenter experience with endovascular treatment of posterior circulation strokes to identify the clinical, radiographic, and procedural predictors of successful recanalization and good neurological outcomes.

Methods—

We performed a multicenter retrospective analysis of consecutive patients with posterior circulation strokes, who underwent thrombectomy with stent retrievers or primary aspiration thrombectomy (including A Direct Aspiration First Pass Technique [ADAPT] approach). We correlated clinical and radiographic outcomes with demographic, clinical, and technical characteristics.

Results—

A total of 100 patients were included in the final analysis (mean age, 63.5±14.2 years; mean admission National Institutes of Health Stroke Scale score, 19.2±8.2). Favorable clinical outcome at 3 months (modified Rankin Scale score ≤2) was achieved in 35% of patients. Successful recanalization and shorter time from stroke onset to the start of the procedure were significant predictors of favorable clinical outcome at 90 days. Stent retriever and aspiration thrombectomy as primary treatment approaches showed comparable procedural and clinical outcomes. None of the baseline advanced imaging modalities (magnetic resonance imaging, computed tomographic perfusion, or computed tomography angiography assessment of collaterals) showed superiority in selecting patients for thrombectomy.

Conclusions—

Time to the start of the procedure is an important predictor of clinical success after thrombectomy in patients with posterior circulation strokes. Both stent retriever and aspiration thrombectomy as primary treatment approaches are effective in achieving successful recanalization.

Abstract TP14: Final Infarct Volume as an Early Indicator the Clinical Outcome: Insight from ESCAPE Trial

Background and Purpose: The goal of reperfusion therapy in acute ischemic stroke is to limit the extension of the ischemic core. The objectives of the present study were to assess the relationship between endovascular treatment and final infarct volume.

Methods and Results: ESCAPE is a multicenter prospective randomized open-label trial with blinded outcome evaluation that enrolled 315 patients (endovascular treatment n=165; control n=150). Of these, 314 patient infarct volumes at 24 hours on CT or MRI were measured blinded to clinical data. Because infarct volumes were non-normally distributed, final infarct volumes were analysed by quartiles. Final infarct volumes were compared by treatment assignment and recanalization/reperfusion status measured by 2-8h CT angiogram in the control group and by formal angiography in the intervention arm.

Results: Median final infarct volume among all study participants was 21 mL (IQR: 7 to 72). Median final infarct volume in endovascular treatment arm at 15.5 mL (IQR: 5 to 46.5) was significantly lower than median final infarct volume in control arm 33.5 mL (IQR: 11 to 95; P=0.0004). Small infarcts, defined as 1st quartile of infarct volumes were more common in the endovascular group compared to control (relative risk [RR] 1.5, CI95 1.02-2.3). Successful recanalization and reperfusion was highly associated with small infarcts (RR 2.2, CI95 1.4-3.4). The proportion of large hemispheric stroke (defined as an infarct volume in the 4th quartile) was much less frequent in the endovascular treatment arm (RR 0.6, CI95 0.3-0.8).

Conclusions: This analysis supports the primary results of ESCAPE trial as endovascular treatment was associated with significantly smaller final infarct volumes. Recanalization/reperfusion was associated with smaller final infarct volume.

Revisiting the NIH Stroke Scale as a screening tool for proximal vessel occlusion: can advanced imaging be targeted in acute stroke?

BACKGROUND AND PURPOSE

Most patients with stroke-like symptoms screened by advanced imaging for proximal occlusion will not have a thrombus accessible by neurointerventional techniques. Development of a sensitive clinical scoring system for rapidly identifying patients with an emergent large vessel occlusion could help target limited resources and reduce exposure to unnecessary imaging.

METHODS

This historical cohort study included patients who underwent non-contrast CT and CT angiography in the emergency department for stroke-like symptoms. NIH Stroke Scale (NIHSS) criteria were extended to include resolved symptoms and dichotomized as present or absent. Combinations of NIHSS criteria were considered as tests for proximal occlusion.

RESULTS

Proximal cerebral vascular occlusion was present in 19.2% (100/522) of the population and, of these, 13% (13/100) had an NIHSS score of 0. The presence on examination or history of diminished consciousness with inability to answer questions, leg weakness, dysarthria, or gaze deviation had 96% sensitivity and 39% specificity for proximal occlusion. If implemented in this population, the use of CT angiography would have been decreased by 32.4% (169/522 patients) while missing 0.76% with proximal occlusions (4/522). Half of those missed (2/4) would have been identified as large vessel infarcts on non-contrast CT, while the remainder (2/4) were transient ischemic attacks associated with carotid stenosis.

CONCLUSIONS

In this cohort, specific NIHSS criteria were highly sensitive for emergent large vessel occlusion and, if validated, may allow for clinical screening prior to advanced imaging with CT angiography.

Ischemic core and hypoperfusion volumes predict infarct size in SWIFT PRIME

OBJECTIVE

Within the context of a prospective randomized trial (SWIFT PRIME), we assessed whether early imaging of stroke patients, primarily with computed tomography (CT) perfusion, can estimate the size of the irreversibly injured ischemic core and the volume of critically hypoperfused tissue. We also evaluated the accuracy of ischemic core and hypoperfusion volumes for predicting infarct volume in patients with the target mismatch profile.

METHODS

Baseline ischemic core and hypoperfusion volumes were assessed prior to randomized treatment with intravenous (IV) tissue plasminogen activator (tPA) alone versus IV tPA + endovascular therapy (Solitaire stent-retriever) using RAPID automated postprocessing software. Reperfusion was assessed with angiographic Thrombolysis in Cerebral Infarction scores at the end of the procedure (endovascular group) and Tmax > 6-second volumes at 27 hours (both groups). Infarct volume was assessed at 27 hours on noncontrast CT or magnetic resonance imaging (MRI).

RESULTS

A total of 151 patients with baseline imaging with CT perfusion (79%) or multimodal MRI (21%) were included. The median baseline ischemic core volume was 6 ml (interquartile range= 0-16). Ischemic core volumes correlated with 27-hour infarct volumes in patients who achieved reperfusion (r = 0.58, p < 0.0001). In patients who did not reperfuse (<10% reperfusion), baseline Tmax > 6-second lesion volumes correlated with 27-hour infarct volume (r = 0.78, p = 0.005). In target mismatch patients, the union of baseline core and early follow-up Tmax > 6-second volume (ie, predicted infarct volume) correlated with the 27-hour infarct volume (r = 0.73, p < 0.0001); the median absolute difference between the observed and predicted volume was 13 ml.

INTERPRETATION

Ischemic core and hypoperfusion volumes, obtained primarily from CT perfusion scans, predict 27-hour infarct volume in acute stroke patients who were treated with reperfusion therapies.

Mechanical Thrombectomy for Isolated M2 Occlusions: A Post Hoc Analysis of the STAR, SWIFT, and SWIFT PRIME Studies

BACKGROUND AND PURPOSE

Mechanical thrombectomy is beneficial for patients with acute ischemic stroke and a proximal anterior occlusion, but it is unclear if these results can be extrapolated to patients with an M2 occlusion. The purpose of this study was to examine the technical aspects, safety, and outcomes of mechanical thrombectomy with a stent retriever in patients with an isolated M2 occlusion who were included in 3 large multicenter prospective studies.

MATERIALS AND METHODS

We included patients from the Solitaire Flow Restoration Thrombectomy for Acute Revascularization (STAR), Solitaire With the Intention For Thrombectomy (SWIFT), and Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment (SWIFT PRIME) studies, 3 large multicenter prospective studies on thrombectomy for ischemic stroke. We compared outcomes and technical details of patients with an M2 with those with an M1 occlusion. All patients were treated with a stent retriever. Imaging data and outcomes were scored by an independent core laboratory. Successful reperfusion was defined as modified Thrombolysis in Cerebral Infarction score of 2b/3.

RESULTS

We included 50 patients with an M2 and 249 patients with an M1 occlusion. Patients with an M2 occlusion were older (mean age, 71 versus 67 years; P = .04) and had a lower NIHSS score (median, 13 versus 17; P < .001) compared with those with an M1 occlusion. Procedural time was nonsignificantly shorter in patients with an M2 occlusion (median, 29 versus 35 minutes; P = .41). The average number of passes with a stent retriever was also nonsignificantly lower in patients with an M2 occlusion (mean, 1.4 versus 1.7; P = .07). There were no significant differences in successful reperfusion (85% versus 82%, P = .82), symptomatic intracerebral hemorrhages (2% versus 2%, P = 1.0), device-related serious adverse events (6% versus 4%, P = .46), or modified Rankin Scale score 0-2 at follow-up (60% versus 56%, P = .64).

CONCLUSIONS

Endovascular reperfusion therapy appears to be feasible in selected patients with ischemic stroke and an M2 occlusion.