Association of Time From Stroke Onset to Groin Puncture With Quality of Reperfusion After Mechanical Thrombectomy: A Meta-analysis of Individual Patient Data From 7 Randomized Clinical Trials

Importance

Reperfusion is a key factor for clinical outcome in patients with acute ischemic stroke (AIS) treated with endovascular thrombectomy (EVT) for large-vessel intracranial occlusion. However, data are scarce on the association between the time from onset and reperfusion results.

Objective

To analyze the rate of reperfusion after EVT started at different intervals after symptom onset in patients with AIS.

Design, Setting, and Participants

We conducted a meta-analysis of individual patient data from 7 randomized trials of the Highly Effective Reperfusion Using Multiple Endovascular Devices (HERMES) group. This is a multicenter cohort study of the intervention arm of randomized clinical trials included in the HERMES group. Patients with anterior circulation AIS who underwent EVT for M1/M2 or intracranial carotid artery occlusion were included. Each trial enrolled patients according to its specific inclusion and exclusion criteria. Data on patients eligible but not enrolled (eg, refusals or exclusions) were not available. All analyses were performed by the HERMES biostatistical core laboratory using the pooled database. Data were analyzed between December 2010 and April 2015.

Main Outcomes and Measures

Successful reperfusion was defined as a modified thrombolysis in cerebral infarction score of 2b/3 at the end of the EVT procedure adjusted for age, occlusion location, pretreatment intravenous thrombolysis, and clot burden score and was analyzed in relation to different intervals (onset, emergency department arrival, imaging, and puncture) using mixed-methods logistic regression.

Results

Among the 728 included patients, with a mean (SD) age of 65.4 (13.5) years and of whom 345 were female (47.4%), decreases in rates of successful reperfusion defined as a thrombolysis in cerebral infarction score of 2b/3 were observed with increasing time from admission or first imaging to groin puncture. The magnitude of effect was a 22% relative reduction (odds ratio, 0.78; 95% CI, 0.64-0.95) per additional hour between admission and puncture and a 26% relative reduction (odds ratio, 0.74; 95% CI, 0.59-0.93) per additional hour between imaging and puncture.

Conclusions and Relevance

Because the probability of reperfusion declined significantly with time between hospital arrival and groin puncture, we provide additional arguments for minimizing the intervals after symptom onset in anterior circulation acute ischemic stroke.

Abstract WMP27: PAT Model Accurately Predicts Aneurysm Enlargement in 16 Growing Aneurysm Cases

Objective: Imaging technology for unruptured intracranial aneurysms (UIA) has improved detection of such aneurysms. However, there is limited information on UIA change over time, and how to predict the rate of enlargement. The objective of this study was to quantify the accuracy of the Predicted Aneurysm Trajectory (PAT) model recently developed by Chien et al. (J Neurosurgery. 2019; Mar 1:1-11).

Methods: Patients diagnosed with UIA were prospectively enrolled at the UCLA Medical Center, and followed through serial imaging. 16 UIA cases exhibiting growth across multiple follow-ups were included in this study. Prior images and medical records were collected. Characteristics relevant to the PAT model (mean ± stdev), including initial UIA size (7.26 ± 6.38), patient age (67.4 ± 9.48 yrs.), sex (4 male), history of smoking (n=5), hypothyroidism (n=4), and follow-up duration (36.5 ± 50.0 mos.) were used to predict UIA size at each follow-up. Predicted and actual UIA sizes at follow-up were compared using symmetric mean absolute percentage error (SMAPE) with percentage error ranging from 0-100%.

Results: The 16 UIA cases were split by initial UIA size. For UIA smaller than 7 mm (10 cases, 23 follow-up), SMAPE = 11.13%. For UIA greater than 7 mm (6 cases, 15 follow-up), SMAPE = 8.07%. For all UIA cases (16 cases, 38 follow-up), SMAPE = 9.92%.

Conclusions: The PAT model predicts the rate of enlargement for UIA, as opposed to whether or not UIA will grow. With this new sample of data, we found the predicted UIA size at follow-up to be quite accurate, deviating in the range of 10% from the actual, measured size. Patient characteristics such as the demographics and behavior included in the model influence the growth of UIA, which allows prediction of growth to optimize treatment and management in future cases.

Abstract WP59: Cerebral Blood Flow Increase After Endovascular Thrombectomy on Perfusion Weighted Image is Associated With Hemorrhagic Transformation

Introduction: The role of increased CBF after endovascular thrombectomy in post-ischemic hyperperfusion has not been studied in detail. We aimed to investigate the timing of CBF increases on PWI after thrombectomy in association with hemorrhagic transformation.

Methods: We analyzed prospectively collected data in consecutive patients treated with endovascular thrombectomy. Inclusion criteria were: (1) patients with ICA or M1 occlusion, and (2) PWI and GRE obtained within 12 hours and 12-48 hours after thrombectomy. We compared each rCBF with early hemorrhage (within 12 hours after thrombectomy), late hemorrhage (12-48 hour) and non-hemorrhage in basal ganglia (BG) and MCA cortical or subcortical (CS) region. In each PWI dataset, ROIs were placed in two slice levels of the BG and three slice levels of the CS region.

Results: Fifty-three patients met inclusion criteria. Early BG hemorrhages were noted in 13 patients, with 4 late BG hemorrhage, 8 early CS hemorrhage and 3 late CS hemorrhage. There were no significant differences on rCBF in PWI within 12 hours after thrombectomy between early hemorrhage, late hemorrhage and non-hemorrhage groups. In contrast, rCBF on 12-48 hours PWI in the BG region was significantly higher in the early BG hemorrhage than non-BG hemorrhage (lower BG slice 1.36 vs 1.01, p<0.001, upper BG slice 1.33 vs 0.96, p<0.001) and rCBF in CS region were significantly higher in early CS hemorrhage than non-CS hemorrhage (lower CS slice 1.55 vs 0.98, p=0.001, middle CS slice 1.31 vs 0.92, p=0.018). There were no significant differences in rCBF on 12-48 hours PWI between the late hemorrhage and non-hemorrhage group.

Conclusions: Most intracerebral hemorrhages after thrombectomy were seen within 12 hours after intervention. A rCBF increase in hemorrhage cases was not seen on PWI within 12 hours after thrombectomy. rCBF increases on PWI 12-48 hours after thrombectomy, however, was associated with post-thrombectomy hemorrhage within 12 hours.

Abstract TP7: Association of Retrieved Thrombus Composition With Measures of Thrombectomy Success

Introduction: Emboli retrieved from stroke patients undergoing mechanical thrombectomy vastly differ in histopathologic appearance, likely reflecting varying etiologies of stroke. We investigated whether clot components correlated with clinical features and thrombectomy outcomes.

Methods: Retrieved thrombi from endovascular thrombectomy in consecutive AIS-LVO patients at 2 academic medical centers were fixed in formalin and sections stained by hematoxylin and eosin. The RBC, WBC and fibrin percentages of the clot were quantified by a neuropathologist blinded to the clinical details. We evaluated the association of these clot components, patient demographic and clinical features, with TICI score (both ordinal and dichotomized at 2c), AOL score, number of thrombectomy passes, and first-pass substantial recanalization (≥TICI 2b result on the first thrombectomy device pass). Non-parametric values were computed via Spearman correlation and pairwise interaction of clinical features was analyzed by ordinal logistic regression.

Results: Among the 75 analyzed patients, mean age was 71.4 (SD 17.7), 50.7% were female and presenting NIHSS mean was 16.1 (SD 7.6). Devices employed were stent retrievers in 71% of patients, aspiration in 10%, and both stent retrievers and aspiration in 19%. Number of passes per procedure was mean 2.16 (SD 1.21). Substantial reperfusion (TICI 2B-3) was achieved in 88% and excellent reperfusion (TICI 2C-3) in 44%. In retrieved thrombi, mean RBC% was 44.8% (SD 31.9) and mean fibrin% was 49.8% (SD 31.4). Rates of first-pass substantial reperfusion, final substantial reperfusion, and final excellent reperfusion were homogenous across wide ranges of retrieved thrombus RBC% and fibrin% in correlation analysis.

Conclusion: RBC and fibrin composition range widely among retrieved thrombi causing acute ischemic stroke. Current generation thrombectomy devices perform well across a broad range of clot compositions.

Abstract TP54: Visual Aids for Patient, Family, and Physician Decision Making About Late Imaging-Guided Endovascular Thrombectomy for Acute Ischemic Stroke

Background: Speedy decision-making is helpful for optimal outcomes from endovascular thrombectomy (EVT) for acute ischemic stroke (AIS). Visual displays may facilitate rapid review of relevant outcomes with different courses of action, but have not yet been developed for late-presenting patients selected for EVT based on multimodal CT or MR imaging.

Methods: From pooled, study-level randomized trial (DAWN and DEFUSE 3) data, 100 person-icon arrays (Kuiper-Marshall personographs) were generated showing beneficial and adverse effects of endovascular thrombectomy for patients with acute cerebral ischemia and large vessel occlusion using (1) automated (algorithmic) and (2) expert-guided joint outcome table specification.

Results: Among imaging-selected patients 6-24 hours from last known well, for the full 7-category modified Rankin Scale (mRS), endovascular thrombectomy had number needed to treat to benefit 1.9 (IQR 1.9-2.1) and number needed to harm 40.0 (29.2-58.3). Visual displays of treatment effects among 100 patients showed that, with EVT: 52 patients have better disability outcome, including 32 more achieving functional independence (mRS 0-2); 3 patients have worse disability outcome, including 1 more experiencing severe disability or death (mRS 5-6), mediated by symptomatic intracranial hemorrhage and infarct in new territory. The person-icon figure integrated these outcomes, and early side-effects, in a single display (Figure). Similar features were present in person-icon figures based on a 6-level mRS (levels 5 and 6 combined) rather than 7-level mRS, and giving special emphasis to normal or near-normal outcome (mRS 0-1) rather than functional independence (mR 0-2).

Conclusion: Personograph visual decision aids are now available to rapidly educate patients, family, and healthcare providers on the benefits and risks of late, imaging-guided endovascular thrombectomy therapies for acute ischemic stroke.

Abstract TP62: Frequency, Characteristics, and Outcomes of Acute Ischemic Stroke Patients With “Total Mismatch” on Penumbral Imaging Before Reperfusion Therapy

Background: When penumbral imaging shows “total mismatch” (large perfusion lesion and no irreversibly infarcted core), the entirety of jeopardized brain is still salvageable and the benefits of reperfusion therapy may be enhanced. The frequency, characteristics, and reperfusion therapy outcomes of total mismatch patients has not been well-characterized.

Methods: Analysis of consecutive acute cerebral ischemia patients in anterior circulation undergoing CT or MR penumbral imaging prior to intravenous thrombolysis (IVT) and/or endovascular thrombectomy (EVT). Patients were classified in four groups: 1) total mismatch (core 0% of perfusion lesion), 2) non-total but substantial mismatch (core 1-20% of perfusion lesion), 3) moderate or no mismatch (core 20-100% of perfusion lesion), and 4) small perfusion lesion (perfusion lesion volume <10 ml).

Results: Among 180 patients, pretreatment imaging patterns were: total mismatch 28.9%, substantial mismatch 22.8%, moderate or no mismatch 22.8%, and small perfusion lesion 25.6%. Among total mismatch patients, the Tmax>6 sec perfusion lesion volume was 56.5 ml (IQR 28.3-85.6) and time from last known well to imaging was 89 mins (IQR 65-296). Compared to moderate patients, clinical features of total mismatch patients were: older (76.0 vs 65.9, p=0.006), lower NIHSS (median 12 vs 18, p=0.019), and more cardioembolism (76.9% vs 48.8%, p=0.005). Total mismatch patients more often had CT than MR (65.4% vs 14.6%, p=0.000), less ICA occlusion (15.4% vs 34.1%, p=0.035), and smaller perfusion lesions (median 56.5 vs 82.1 ml, p=0.007). Total mismatch patients were treated with combined IVT+EVT in 32.7%, IVT alone in 26.9%, and EVT alone in 40.4%. Freedom from disability (mRS 0-1) at discharge was more frequent, 35.6% vs 16.2%, p=0.049 and disability levels at day 90 were lower in total mismatch patients, mean mRS 2.7 vs 3.9, p=0.029.

Conclusion: Total mismatch is present in one-quarter of patients undergoing reperfusion therapy, more often in older patients with cardioembolism as etiology of stroke. Total mismatch patients have better disability outcomes from reperfusion therapy, but more than half show disability indicating need for more complete reperfusion.

Abstract 170: Impact of Eloquent Motor Cortex-Tissue Reperfusion Beyond the Traditional TICI Scoring After Thrombectomy

Background: Targeted eloquence-based tissue reperfusion within the primary motor cortex may have differential effect on disability as compared to the traditional volume-based (TICI) reperfusion after endovascular thrombectomy (EVT) in setting of acute ischemic stroke (AIS).

Methods: We explored the impact of eloquent reperfusion (ER) within primary motor cortex (PMC) on clinical outcome (mRS) in AIS patients undergoing EVT. ER was defined as presence of flow on final digital subtraction angiography (DSA) within four main cortical branches, supplying the PMC (MCA - precentral, central, anterior parietal; ACA- pericallosal) and graded as absent (0), partial (1), and complete (2). Prospectively collected data from two centers were analyzed. Multivariable analysis was conducted to assess the impact of ER on 90-day disability (mRS) among patients with anterior circulation occlusion who achieved partial reperfusion (TICI 2 a and b).

Results: Among the 125 patients who met study criteria, median age was 73, median NIHSS was 16, median ASPECTS was 7, 48% (60/125) were female, and 36.8% achieved functional independence (mRS 0-2) at 90 days. ER distribution was: Absent (0) in 19/125 (15.2%); Partial (1) in 52/125 (41.6%), and Complete (2) in 54/125 (43.2%). TICI 2b was achieved in 102/125 (81.6%) and ER was substantially higher in those patients (p<0.001). In multivariate analysis, in addition to age and sICH, ER had a profound independent impact on 90-day disability (OR 6.10, p=0.001 for ER 1 vs 0; and OR 9.87, p<0.001 for ER 2 vs 0). In contrast, extent of total partial reperfusion (TICI 2b vs 2a) was not related to 90-day disability.

Conclusions: Our findings support that eloquent PMC-tissue reperfusion is a major determinant of functional outcome, more impactful than volume-based degree of partial reperfusion. More aggressive, PMC-targeted revascularization among patients with non-eloquent partial reperfusion may further improve post-stroke disability after EVT.

Abstract WP66: Impaired Collaterals Are Associated With Intracranial Thrombus Extension: Evidence From MRI, Catheter Angiography, and Retrieved Thrombus Composition

Background: Clot propagation after initial occlusion may increase target thrombus burden and its pathophysiologic basis has not been extensively studied in acute human ischemic stroke. We investigated whether clot characteristics on MRI, catheter angiography, and thrombus histopathology indicated that impaired collaterals may be associated with extension of acute intracranial occlusions via stasis clotting in slow flow arterial segments.

Methods: Analysis of consecutive AIS-LVO endovascular thrombectomy patients at 2 academic medical centers with: 1) pretreatment MRI, and 2) retrieved thrombi. GRE MR susceptibility vessel sign presence and extent of ASITN collateral scores were rated by blinded assessors. Extracted clots were fixed in formalin, stained by hematoxylin and eosin, and RBC, WBC and fibrin percent composition quantified by a neuropathologist blinded to clinical details. We evaluated the correlation of collateral grade with clot size by susceptibility vessel sign (SVS) and clot composition by RBC%. Non-parametric values were computed via Spearman correlation.

Results: Among the 48 patients, mean age was 71.4 (SD 17.7), 56.3% female, and mean presenting NIHSS was 15.5 (SD 7.41). A susceptibility vessel sign was present in 65%, with mean SVS length 15.6 mm (SD 8.3). Collateral scores were mean 2.3 (SD 1.2). The number of passes per procedure was mean 1.98 (SD 1.30) The presence of a susceptibility vessel sign correlated with higher RBC% in retrieved thrombi (r s =0.36 p=0.011). Worse collateral grades correlated with longer SVS length (r s =-0.50 p=0.004) and greater SVS width (r s =-0.54 p=0.002). Worse collateral grade also trended toward correlation with higher RBC% in retrieved clots (r s =-0.19 p=0.18).

Conclusion: Impaired angiographic collaterals are associated with longer RBC-rich thrombi on susceptibility imaging and trend toward association with higher RBC% in retrieved thrombi. These findings support that, in LVO acute ischemic stroke, clot propagation after initial occlusion occurs by stasis clotting accelerated by impaired collaterals.

Abstract WP111: The Role of Intravenous Tissue Plasminogen Activator in Acute Ischemic Stroke With Large Vessel Occlusion

Introduction: Current guidelines recommend administration of intravenous tissue plasminogen activator (IVT) for all eligible patients with acute ischemic stroke (AIS) with large vessel occlusion (LVO). Recent observational data question the safety and efficacy of IVT in AIS patients with LVO undergoing mechanical thrombectomy (MT).

Methods: Retrospective analysis using prospectively collected database on all AIS patients with LVO treated at our institution over 3 consecutive years. Stroke outcomes and adverse events were compared between patients who underwent IVT+MT versus MT only. Stroke outcomes were adjusted for known comorbidities, last know well time and core volume on pretreatment imaging.

Results: 158 AIS patients with LVO were treated. 69 patients had treatment strategy of IVT+MT, 89 patients MT only. 7 (10%) patients treated with IVT had successful reperfusion before MT. IVT+MT, compared with MT alone, was associated with reduced 90day mortality (22.4% vs 40.8%, p:0.03) and reduced 90day severe disability or death (mRS 4-6: 48% vs 67%, p:0.03). Door-to-puncture time (DTP) was longer with IVT. IVT was not associated with increased intracranial hemorrhage but was associated with increased access site hematomas (16.9% vs 5.7%, p:0.03). Both groups showed similar proportion of patients ≥TICI2c (IVT+MT: 48% vs MT: 47%), however IVT+MT patients had greater proportion of TICI2c than TICI3. (IVT+MT TICI2c:30.4% vs MT TICI2c:17%)

Conclusions: IVT before MT in AIS with LVO, results in reperfusion prior to thrombectomy in 10% of patients, and is associated with reduced mortality and severe disability at 90days. However, IVT+MT is associated with more access site hematomas and increased TICI 2C vs TICI 3 reperfusion, suggesting increased distal embolization due to thrombus fragmentation. The use of balloon guide for proximal flow arrest and aspiration during thrombectomy should be considered.

Abstract TP19: Thrombectomy in Medium Arteries Works for Distal Vessel Occlusions in Acute Ischemic Stroke - STRATIS

Background: Mechanical thrombectomy is established for large vessel occlusions in acute ischemic stroke, but the potential role in distal vessel occlusions of medium arteries is largely unknown. Such distal arterial segments have not been measured with respect to thrombectomy devices used during endovascular therapy. We conducted a systematic analysis of arterial size, segmental anatomy and stent retriever device performance during thrombectomy.

Methods: The STRATIS angiography core lab adjudicated the exact location of the occlusion, proximal and distal device deployment, relationship to arterial bifurcations and anatomical nomenclature. Arterial diameters were measured at all of these sites. Statistical analyses examined the relationship between these variables, arterial recanalization and eTICI reperfusion.

Results: Thrombectomy was performed with various device sizes, including Solitaire 4x40 in 36.3% (306/844), Solitaire 6x30 in 31.4% (265/844), Solitaire 4x20 in 26.4% (223/844), unspecified in 3.8% (32/844), Solitaire 6x20 in 1.3% (11/844) and Solitaire 4x15 in 0.8% (7/844). Arterial diameter at the occlusion site was median 2.17mm (1.40-3.59) in the distal M1, 1.67mm (0.81-2.98) in the proximal M2, 1.50mm (0.92-1.99) in the distal M2, 1.24mm (0.67-2.00) in the M3 and 1.88mm (1.49-1.94) in the P1. Considerable overlap was noted between arterial sizes at occlusion sites carrying different segmental arterial nomenclature or vessel names. During device deployment in STRATIS, median arterial diameter at the occlusion site was 2.4mm (IQR 1.9, 3.4), 2.9mm (IQR 2.2, 3.6) at the proximal stent marker and 1.4mm (IQR 1.2, 1.7) at the distal stent marker. Substantial eTICI reperfusion (2b-3) was achieved in all distal vessel occlusions (Table 1).

Conclusions: Substantial reperfusion may be achieved with currently available mechanical thrombectomy devices for distal vessel occlusions in medium arteries.

Abstract WP85: Clinical and Imaging Predictors, and Functional Outcomes, of Fast, Intermediate, and Slow Progression Among Patients With Large Vessel Occlusion Acute Ischemic Stroke

Background: Speed of infarct progression varies widely in acute ischemic stroke and is a major determinant of outcome. Patient demographic, clinical, and imaging features associated with slow, intermediate, and rapid infarct growth have not been well delineated.

Methods: In a prospectively maintained stroke center registry, we analyzed consecutive patients with anterior circulation large vessel occlusion who underwent first multimodal MRI or CT imaging within 24 hours of onset. The speed of initial infarct progression was calculated as ischemic core volume at first imaging divided by the time from stroke onset to imaging.

Results: Among the 88 patients, age was mean 71.6 ± 15.0; 51% were women; initial NIHSS was 16.1 ± 6.5), and time from onset to first imaging was median 3.3h (full range 0.6 - 23.0). The speed of infarct progression was median 2.2 cc/hr (interquartile range 0 - 8.7), ranging most widely among patients imaged within the first 6 hours after onset. Faster speed of infarct progression was positively independently associated with low collateral score (OR 3.30, 95%CI 1.25 - 10.49) and arrival by emergency medical services rather than transfer (OR 3.34, 95% CI 1.06 - 10.49) and negatively independently associated with prior ischemic stroke (OR 0.12, 95%CI 0.03 - 0.50) and coronary artery disease (OR 0.32, 95%CI 0.10 - 1.00). Among the 67 patients who underwent endovascular thrombectomy, slower speeds of infarct progression were associated with shift to reduced levels of disability at discharge (OR 3.26, 95% CI 1.02 - 10.45). In addition, slower speed of infarct progression was associated with favorable shift to recanalization by thrombectomy (OR 8.30, 95%CI 0.97 - 70-.87) and reduced radiologic hemorrhagic transformation (OR 0.34, 95% CI 0.12 - 0.94).

Conclusion: Slower speed of initial infarct progression is associated with high collateral score, prior ischemic stroke, and coronary artery disease, supporting roles for both collateral robustness and ischemic precondition in fostering tissue resilience to ischemia. Among patients undergoing endovascular thrombectomy, speed of initial infarct progression is a major determinant of clinical outcome.

Abstract WP24: Arterial Tortuosity is a Potent Determinant of Safety in Endovascular Therapy for Ischemic Stroke

Background: Subarachnoid hemorrhage (SAH) associated with vessel injury during endovascular therapy for acute ischemic stroke is a known complication. Arterial anatomy may predispose to increased risk of SAH and technical safety, yet factors such as clot location, arterial size and tortuosity have not been explored. We examined these anatomical factors with respect to SAH during thrombectomy.

Methods: Arterial anatomy at the site of occlusion and mechanical thrombectomy during device deployment was detailed by the STRATIS core lab. Luminal diameters, arterial branching and segmental tortuosity were measured. Arterial tortuosity was quantified using the distance factor metric (DFM). Statistical analyses included descriptives of arterial anatomy, with univariate and multivariate modeling to predict SAH.

Results: Arterial tortuosity in each segment from the proximal cerebral arteries to the site of occlusion was quantified in 790 subjects treated with mechanical thrombectomy in STRATIS. Cumulative arterial tortuosity to the site of vessel occlusion was greater in distal lesions (Table 1). SAH was clearly linked with more distal thrombectomy (p=0.017), with 19.0% of distal M2, 16.7% of M3, 7.3% of distal M1, 5.8% of proximal M2, 2.4% of distal ICA and 2.1% of proximal M1. Multivariate prediction of SAH revealed that arterial diameter was unrelated to SAH (p=0.30) when accounting for tortuosity, whereas the presence of tortuosity tripled the risk of SAH (OR 3, p<0.05).

Conclusions: This novel systematic analysis of arterial tortuosity and angiographic anatomy during mechanical thrombectomy establishes tortuosity as a determinant of SAH, providing insight for future techniques and innovative device designs.

Abstract TP492: Novel in vitro Model of Arteriovenous Malformation for Endovascular Embolization and Flow Analysis

Introduction: 3D printed human vascular in vitro models of aneurysms and acute stroke have been utilized for training, simulation and device development. However, there are no realistic in vitro arteriovenous malformation (AVM) models. Current experimental models analyzing the efficacy of embolic materials or flow conditions are limited by their simplistic design, lacking complex AVM nidus anatomic features. The purpose of this study is to develop a new in vitro AVM model for embolic material testing and flow analysis.

Methods: 3D images of the AVM nidus were extracted from 3D rotational angiography from a patient. Artificial feeders and drainers were added to the nidus and an inner vascular mold was printed using a 3D printer. The inner mold was coated with polydimethylsiloxanes. The inner plastic mold was removed by acetone, leaving a hollow AVM model. ONYX injection and 4DFlow MRI (Phase Contrast MRA) were performed using the AVM models. In addition, computational fluid dynamics (CFD) analysis was performed to compare flow rate with 4DFlow MRI.

Results: An in vitro AVM model with realistic representation of nidus vasculature and complexity was successfully created. Liquid onyx injection performed in the in vitro model successfully replicated real-life treatment conditions. The model effectively simulated plug and push technique before penetration of the ONYX into the AVM nidus. 4DFlow MRI flow rates were similar to the CFD analysis.

Conclusions: An in vitro AVM model using 3D printing technology was successfully created. The model demonstrated realistic pliability during ONYX injection. This in vitro AVM model may represent a useful tool for training and development of new materials, and have potential of highly-resolved flow quantifications.

Impact of Hyperglycemia According to the Collateral Status on Outcomes in Mechanical Thrombectomy

Background and Purpose- Understanding the influence of hyperglycemia on outcomes in terms of the pretreatment collateral status might contribute to the achievement of case-specific glucose management in acute ischemic stroke. We sought to investigate whether the glucose level can influence the pretreatment collateral status and functional outcomes of endovascular thrombectomy in acute ischemic stroke and whether the impact of hyperglycemia on outcomes can be modified by the pretreatment collateral status. Methods- We analyzed the Triple-S database, which includes individual patient data pooled from 3 prospective Solitaire stent retriever studies (SWIFT [Solitaire With the Intention for Thrombectomy], SWIFT PRIME [SWIFT as Primary Endovascular Treatment], and STAR [Solitaire Flow Restoration Thrombectomy for Acute Revascularization]). Patients were eligible if they had acute ischemic stroke with moderate to severe neurological deficits, harbored angiographically confirmed large vessel occlusion, and were treatable by endovascular thrombectomy within 8 hours of onset. Pretreatment catheter angiograms were scored for collateral grades by a core imaging laboratory. The main outcome was 3-month good outcome (modified Rankin Scale score of 0-2). Results- Angiographic data on collaterals were available in 309 patients (age, 67±12 years; glucose, 131±55 mg/dL). Overall, the glucose level at presentation was not associated with pretreatment collateral status but was significantly lower in patients with a good outcome at 90 days (124 versus 140 mg/dL). Collateral grades modified the effect of glucose on good outcomes at 90 days ( P_int=0.03). Among patients with poor collaterals (collateral grades, 0-2), higher glucose levels did not alter the outcome, whereas among patients with good collaterals (3-4), higher glucose levels reduced the likelihood of a good outcome at 90 days (per 10 mg/dL increase: odds ratio, 0.81; 95% CI, 0.69-0.95). Conclusions- Our study revealed that higher glucose levels reduce the likelihood of a good outcome among patients with good collaterals, but their effects on the outcome are less significant for patients with poor collaterals. The results suggest that good collaterals at presentation may be targets for more intensive glucose control and future studies relating to glucose management.

Sex Differences in Outcome After Endovascular Stroke Therapy for Acute Ischemic Stroke

Background and Purpose- We determined the effect of sex on outcome after endovascular stroke thrombectomy in acute ischemic stroke, including lifelong disability outcomes. Methods- We analyzed patients treated with the Solitaire stent retriever in the combined SWIFT (Solitaire FR With the Intention for Thrombectomy), STAR (Solitaire FR Thrombectomy for Acute Revascularization), and SWIFT PRIME (Solitaire FR With the Intention for Thrombectomy as Primary Endovascular Treatment) cohorts. Ordinal and logistic regression were used to examine known factors influencing outcome after endovascular stroke thrombectomy and study the effect of sex on the association between these factors and outcomes, including age and time to reperfusion. Years of optimal life after thrombectomy were defined as disability-adjusted life years and calculated by projecting disability through adjusted poststroke life expectancy by sex. Results- Among 389 patients treated with endovascular stroke thrombectomy, 55% were females, and median National Institutes of Health Stroke Scale was 17 (interquartile range, 8-28). There were no differences between females versus males in presenting deficit severity (National Institutes of Health Stroke Scale score, 17 versus 17, P=0.21), occlusion location (69% versus 64% M1, P=0.62), presenting infarct extent (Alberta Stroke Program Early CT Score 8 versus 8, P=0.24), rate of substantial reperfusion (Thrombolysis in Cerebral Infarction 2b/3, 87% versus 83%, P=0.37), onset to reperfusion time (294 versus 302 minutes, P=0.46). Despite older ages (69 versus 64, P<0.001) and higher rate of atrial fibrillation (45% versus 30%, P=0.002) for females compared with males, adjusted rates of functional independence at 90 days were similar (odds ratio, 1.0; 95% CI, 0.6-1.6). After adjusting for age at presentation and stroke severity, females had more years of optimal life (disability-adjusted life year) after endovascular stroke thrombectomy, 10.6 versus 8.5 years (P<0.001). Conclusions- Despite greater age and higher rate of atrial fibrillation, females experienced comparable functional outcomes and greater years of optimal life after intervention compared with males.

Association Between Time to Treatment With Endovascular Reperfusion Therapy and Outcomes in Patients With Acute Ischemic Stroke Treated in Clinical Practice

IMPORTANCE

Randomized clinical trials suggest benefit of endovascular-reperfusion therapy for large vessel occlusion in acute ischemic stroke (AIS) is time dependent, but the extent to which it influences outcome and generalizability to routine clinical practice remains uncertain.

OBJECTIVE

To characterize the association of speed of treatment with outcome among patients with AIS undergoing endovascular-reperfusion therapy.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study using data prospectively collected from January 2015 to December 2016 in the Get With The Guidelines-Stroke nationwide US quality registry, with final follow-up through April 15, 2017. Participants were 6756 patients with anterior circulation large vessel occlusion AIS treated with endovascular-reperfusion therapy with onset-to-puncture time of 8 hours or less.

EXPOSURES

Onset (last-known well time) to arterial puncture, and hospital arrival to arterial puncture (door-to-puncture time).

MAIN OUTCOMES AND MEASURES

Substantial reperfusion (modified Thrombolysis in Cerebral Infarction score 2b-3), ambulatory status, global disability (modified Rankin Scale [mRS]) and destination at discharge, symptomatic intracranial hemorrhage (sICH), and in-hospital mortality/hospice discharge.

RESULTS

Among 6756 patients, the mean (SD) age was 69.5 (14.8) years, 51.2% (3460/6756) were women, and median pretreatment score on the National Institutes of Health Stroke Scale was 17 (IQR, 12-22). Median onset-to-puncture time was 230 minutes (IQR, 170-305) and median door-to-puncture time was 87 minutes (IQR, 62-116), with substantial reperfusion in 85.9% (5433/6324) of patients. Adverse events were sICH in 6.7% (449/6693) of patients and in-hospital mortality/hospice discharge in 19.6% (1326/6756) of patients. At discharge, 36.9% (2132/5783) ambulated independently and 23.0% (1225/5334) had functional independence (mRS 0-2). In onset-to-puncture adjusted analysis, time-outcome relationships were nonlinear with steeper slopes between 30 to 270 minutes than 271 to 480 minutes. In the 30- to 270-minute time frame, faster onset to puncture in 15-minute increments was associated with higher likelihood of achieving independent ambulation at discharge (absolute increase, 1.14% [95% CI, 0.75%-1.53%]), lower in-hospital mortality/hospice discharge (absolute decrease, -0.77% [95% CI, -1.07% to -0.47%]), and lower risk of sICH (absolute decrease, -0.22% [95% CI, -0.40% to -0.03%]). Faster door-to-puncture times were similarly associated with improved outcomes, including in the 30- to 120-minute window, higher likelihood of achieving discharge to home (absolute increase, 2.13% [95% CI, 0.81%-3.44%]) and lower in-hospital mortality/hospice discharge (absolute decrease, -1.48% [95% CI, -2.60% to -0.36%]) for each 15-minute increment.

CONCLUSIONS AND RELEVANCE

Among patients with AIS due to large vessel occlusion treated in routine clinical practice, shorter time to endovascular-reperfusion therapy was significantly associated with better outcomes. These findings support efforts to reduce time to hospital and endovascular treatment in patients with stroke.

Onset to reperfusion time as a determinant of outcomes across a wide range of ASPECTS in endovascular thrombectomy: pooled analysis of the SWIFT, SWIFT PRIME, and STAR studies

Background

The time–benefit relationship of endovascular thrombectomy (EVT) according to the size of the core infarct has been incompletely explored in prior studies. We investigated whether established infarct core size on baseline imaging modifies the relationship between onset-to-reperfusion time (OTR) and functional outcomes in patients with acute ischemic stroke treated with EVT.

Methods

We analyzed a database containing individual patient data pooled from three prospective Solitaire stent retriever studies. The inclusion criteria were treatment with a Solitaire device and achievement of substantial reperfusion (modified Thrombolysis in Cerebral Infarction 2b–3). Main analyses were performed in patients with baseline Alberta Stroke Program Early CT Scores (ASPECTSs) of 7–10.

Results

Among the 305 patients (mean age 67±13 years, 58% women), the proportions of patients in different categories of pretreatment infarct extent were: small (ASPECTS 9–10) 52.0%, moderate (ASPECTS 7–8) 37.1%, and large (ASPECTS 0–6) 7.6%. The mean OTR was 297±95 min. At 3 months, 60.1% of the patients achieved a good outcome. For OTRs of 2–8 hours, the rates of good outcomes at all time points were higher with higher baseline ASPECTS but declined with similar steepness. Both baseline ASPECTS (OR 1.23 (95% CI 1.04 to 1.45)) and OTR (every 30 min delay, OR 0.80 (95% CI 0.73 to 0.88)) were independently associated with a good 3-month outcome. No interaction between OTR and baseline ASPECTS was observed.

Conclusions

Although patients with higher baseline ASPECTS are more likely to have good clinical outcomes at all OTR intervals after 2 hours, this benefit consistently declines with time, even in patients with a small infarct core, reinforcing the need to treat all patients as quickly as possible.

The impact of general anesthesia, baseline ASPECTS, time to treatment, and IV tPA on intracranial hemorrhage after neurothrombectomy: pooled analysis of the SWIFT PRIME, SWIFT, and STAR trials

BACKGROUND

Despite the proven benefit of neurothrombectomy, intracranial hemorrhage (ICH) remains the most serious procedural complication. The aim of this analysis was to identify predictors of different hemorrhage subtypes and evaluate their individual impact on clinical outcome.

METHODS

Pooled individual patient-level data from three large prospective multicenter studies were analyzed for the incidence of different ICH subtypes, including any ICH, hemorrhagic transformation (HT), parenchymal hematoma (PH), subarachnoid hemorrhage (SAH), and symptomatic intracranial hemorrhage (sICH). All patients (n=389) treated with the Solitaire device were included in the analysis. A multivariate stepwise logistic regression model was used to identify predictors of each hemorrhage subtype.

RESULTS

General anesthesia and higher baseline Alberta Stroke Program Early CT score (ASPECTS) were associated with a lower probability of any ICH (OR 0.36, p=0.003), (OR 0.80, p=0.032) and HT (OR 0.54, p=0.023), (OR 0.78, p=0.001), respectively. Longer time from onset to treatment was associated with a higher likelihood of HT (OR 1.08, p=0.001) and PH (OR 1.11, p=0.015). Intravenous tissue plasminogen activator (IV-tPA) was also a strong predictor of PH (OR 7.63, p=0.013). Functional independence at 90 days (modified Rankin Scale (mRS) 0-2) was observed significantly less frequently in all hemorrhage subtypes except SAH. None of the patients who achieved functional independence at 90 days had sICH.

CONCLUSIONS

General anesthesia and smaller baseline ischemic core are associated with a lower probability of HT whereas IV-tPA and prolonged time to treatment increase the risk of PH after neurothrombectomy.

TRIAL REGISTRATION NUMBERS

SWIFT-NCT01054560; post results, SWIFT PRIME-NCT01657461; post results, STAR-NCT01327989; post results.

The α2,3-selective potentiator of GABAA receptors, KRM-II-81, reduces nociceptive-associated behaviors induced by formalin and spinal nerve ligation in rats

Clinical evidence indicates that positive allosteric modulators (PAMs) of GABAA receptors have analgesic benefit in addition to efficacy in anxiety disorders. However, the utility of GABAA receptor PAMs as analgesics is compromised by the central nervous system side effects of non-selective potentiators. A selective potentiator of GABAA receptors associated with α2/3 subunits, KRM-II-81(5-(8-ethynyl-6-(pyridin-2-yl)-4H-benzo[f]imidazo[1,5-a][1,4]diazepin-3-yl)oxazole), has demonstrated anxiolytic, anticonvulsant, and antinociceptive effects in rodents with reduced motoric side effects. The present study evaluated the potential of KRM-II-81 as a novel analgesic. Oral administration of KRM-II-81 attenuated formalin-induced flinching; in contrast, diazepam was not active. KRM-II-81 attenuated nociceptive-associated behaviors engendered by chronic spinal nerve ligation (L5/L6). Diazepam decreased locomotion of rats at the dose tested in the formalin assay (10 mg/kg) whereas KRM-II-81 produced small decreases that were not dose-dependent (10-100 mg/kg). Plasma and brain levels of KRM-II-81 were used to demonstrate selectivity for α2/3- over α1-associated GABAA receptors and to define the degree of engagement of these receptors. Plasma and brain concentrations of KRM-II-81 were positively-associated with analgesic efficacy. GABA currents from isolated rat dorsal-root ganglion cultures were potentiated by KRM-II-81 with an ED50 of 32 nM. Measures of respiratory depression were reduced by alprazolam whereas KRM-II-81 was either inactive or produced effects with lower potency and efficacy. These findings add to the growing body of data supporting the idea that α2/3-selective GABAA receptor PAMs will have efficacy and tolerability as pain medications including those for neuropathic pain. Given their predicted anxiolytic effects, α2/3-selective GABAA receptor PAMs offer an additional inroad into the management of pain.

Association of Serum Vitamin D (25OHD) Level with Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Acute exacerbations of COPD is characterized by a change in the patients baseline dyspnoea, cough and/or sputum that is beyond normal day to day differences and guides to a change in standard medications in a patient with COPD. Vitamin D influences the innate & adaptive immune system, and exerts pleiotropic antimicrobial and anti-inflammatory responses. Vitamin D deficiency is frequent among COPD patients but its contributory role in disease exacerbations is widely debated. This study was aimed to assess relationship between reduced serum vitamin D (25-OHD) level with COPD severity and acute exacerbation. This observational cross-sectional study was carried out in the department of Respiratory Medicine, NIDCH, Mohakhali, Dhaka, Bangladesh from October 2016 to September 2017. Consecutive 80 hospital admitted patients with acute exacerbation of chronic obstructive pulmonary disease diagnosed on the basis of clinical history & pulmonary function tests and 78 age & sex matched controls were investigated for serum vitamin D (25-OHD) level. Among the COPD patients, 37% had Vitamin D deficiency (<20ng/ml) and 28.75% had Vitamin D insufficiency (20-29ng/ml). Mean vitamin D (25-OHD) level of COPD patients (25.82±10.62ngm/ml) was found to be significantly lower than healthy controls (32.57±11.32ngm/ml). Vitamin D deficiency was found, by Pearson correlation test, to be significantly associated with severity of COPD. Multivariate analysis showed that age (in years), FEV1 (percent predicted), frequent exacerbators (≥2 in the last year), and smoking (>40 pack year) were significantly associated with Vitamin D deficiency. Acute exacerbation of chronic obstructive pulmonary disease patients was found to have vitamin D deficiency and vitamin D deficiency was significantly associated with severity of COPD. Vitamin D deficiency was also associated with frequent disease exacerbation.

Pre-procedural simulation for precision stent-assisted coiling of cerebral aneurysm

Artificial vascular models are emerging as a newly-inexpensive and accurate way to simulate a procedure before the treatment. Through utilization of precision three-dimensionally printed, silicone-reconstructed, patient-specific models of aneurysms, we can compare the performance of devices including stents, and accurately predict the behavior of the microcatheter and stent-assisted coiling in the aneurysm to not only reduce procedural time, but also make the procedure safer. Here we report two challenging cases of wide-necked aneurysms, which could be safely treated with stent-assisted coiling as simulated in the patient-specific aneurysm models.

Impact of procedural time on clinical and angiographic outcomes in patients with acute ischemic stroke receiving endovascular treatment

Background

Procedural time in patients with acute ischemic stroke (AIS) undergoing mechanical thrombectomy may affect clinical outcomes. We performed a pooled analysis of the effect of procedural time on clinical outcomes using data from three prospective endovascular treatment trials.

Objective

To examine the relationship between endovascular procedural time and clinical outcomes of patients with AIS following endovascular treatment.

Methods

We analyzed data from SWIFT, STAR, and SWIFT PRIME studies, including baseline characteristics: National Institutes of Health Stroke Scale (NIHSS) score on admission, intracranial hemorrhage rates, and modified Rankin Scale score at 3 months. The Thrombolysis in Cerebral Infarction (TICI) scale was used to grade postprocedure recanalization. We recorded two procedural time intervals: (1) symptom onset to groin puncture and (2) groin puncture to angiographic recanalization. A multivariate analysis was performed using a logistic regression model to analyze predictors of unfavorable outcome.

Results

We analyzed 301 patients who had undergone endovascular treatment and had near-complete or complete recanalization (TICI 2b or 3). At 3 months, 122 patients (40.5%) had unfavorable outcomes. The rate of favorable outcomes was significantly higher when the procedural time was <60 min compared with ≥60 min (62% vs 45%, p=0.020). Predictors of unfavorable outcome at 3 months were age (unit 10 years, OR=0.62, 95% CI 0.46 to 0.82, p<0.001), onset to groin puncture time (unit hour, OR=0.61, 95% CI 0.48 to 0.77, p<0.001), groin puncture to recanalization (unit 10 min, OR=0.89, 95% CI 0.80 to 0.99, p=0.032), baseline NIHSS score (20–28 vs 8–10, OR=0.17, 95% CI 0.05 to 0.62, p=0.018), and collaterals (OR=1.48, 95% CI 1.04 to 2.10, p=0.029).

Conclusion

Procedural time in patients with stroke undergoing mechanical thrombectomy may be an important determinant of favorable outcomes in those with recanalization.

Unruptured intracranial aneurysm growth trajectory: occurrence and rate of enlargement in 520 longitudinally followed cases

OBJECTIVE

As imaging technology has improved, more unruptured intracranial aneurysms (UIAs) are detected incidentally. However, there is limited information regarding how UIAs change over time to provide stratified, patient-specific UIA follow-up management. The authors sought to enrich understanding of the natural history of UIAs and identify basic UIA growth trajectories, that is, the speed at which various UIAs increase in size.

METHODS

From January 2005 to December 2015, 382 patients diagnosed with UIAs (n = 520) were followed up at UCLA Medical Center through serial imaging. UIA characteristics and patient-specific variables were studied to identify risk factors associated with aneurysm growth and create a predicted aneurysm trajectory (PAT) model to differentiate aneurysm growth behavior.

RESULTS

The PAT model indicated that smoking and hypothyroidism had a large effect on the growth rate of large UIAs (≥ 7 mm), while UIAs < 7 mm were less influenced by smoking and hypothyroidism. Analysis of risk factors related to growth showed that initial size and multiplicity were significant factors related to aneurysm growth and were consistent across different definitions of growth. A 1.09-fold increase in risk of growth was found for every 1-mm increase in initial size (95% CI 1.04-1.15; p = 0.001). Aneurysms in patients with multiple aneurysms were 2.43-fold more likely to grow than those in patients with single aneurysms (95% CI 1.36-4.35; p = 0.003). The growth rate (speed) for large UIAs (≥ 7 mm; 0.085 mm/month) was significantly faster than that for UIAs < 3 mm (0.030 mm/month) and for males than for females (0.089 and 0.045 mm/month, respectively; p = 0.048).

CONCLUSIONS

Analyzing longitudinal UIA data as continuous data points can be useful to study the risk of growth and predict the aneurysm growth trajectory. Individual patient characteristics (demographics, behavior, medical history) may have a significant effect on the speed of UIA growth, and predictive models such as PAT may help optimize follow-up frequency for UIA management.

Abstract TMP62: Emergency Triage to Predict Collaterals in Acute Ischemic Stroke: Imaging Bests Clinical Factors in the STRATIS Registry

Background: Collateral grade is an established determinant of outcomes in acute ischemic stroke (AIS). The triage, workflow and therapeutic options for AIS may be tailored to collaterals and identifying key predictors of collateral status may therefore be crucial. We hypothesized that degree of collateral circulation prior to endovascular therapy in AIS may be predicted at the time of initial patient evaluation and triage.

Methods: The STRATIS Registry showed that timelines, technical, and functional outcomes could be effectively attained in a large real-world cohort of endovascular therapy. Baseline clinical and imaging predictors of core lab adjudicated collateral grade (ASITN) by conventional angiography were determined, using multivariate modeling.

Results: 586 STRATIS subjects (67.5 ± 15.2 years, 52.7% male) presenting with AIS at 147.4 ± 101.8 min from symptom onset (TFSO) and median NIHSS score 17.0 (range 8.0,30.0) were analyzed. Collateral grade was poor (ASITN 0-1) in 81, moderate (ASITN 2) in 297 and good (ASITN 3-4) in 208. Baseline stroke severity inversely correlated with collaterals (NIHSS per point, OR 0.946, 0.916-0.977, p=0.001), yet no clinical variables such as age, sex or co-morbidities were predictive of collateral status. Less severe ASPECTS at imaging triage (median 9, range 2-10) was associated with better collateral grade (ASITN 0-1, median 7 (2-10); ASITN 2, 8 (3-10); ASITN 3-4, 9 (5-10), p<0.001) and the strongest predictor of collaterals during triage (per point, OR 1.608, 1.399-1.849, p<0.001). Interestingly, the predictive nature of ASPECTS was not modified by TFSO (p=NS). Specific ASPECTS regions (all cortical M1-M6, but no subcortical) affected by early ischemia were also predictive of collateral grade. In particular, insular ASPECTS changes at imaging triage was the strongest predictor of collateral grade (ASITN 0-1, 53/66 (80.3%); ASITN 2, 139/258 (53.9%); ASITN 3-4, 41/194 (21.1%), p<0.001).

Conclusions: Imaging, using only ASPECTS, during triage strongly predicts collateral grade, irrespective of time from symptom onset. Clinical variables, however, may not be used to accurately predict collaterals in the real-world practice of endovascular therapy.

Abstract TP287: Efficient Multimodal-MRI versus CT Selection for Anterior Circulation Large Vessel

Background: Prompt diagnosis and revascularization of large vessel occlusion ischemic stroke is associated with better functional outcome. While both MRI and CT modalities are current standard of care options for initial imaging, and MR imaging provides greater lesion conspicuity and spatial resolution to inform management, few series have yet demonstrated that multimodal MR may be performed speedily and efficiently in AIS-LVO patients.

Methods: In a prospectively maintained Comprehensive Stroke Center Registry, we analyzed all anterior circulation LVO thrombectomy patients: 1) arriving directly by EMS transport from the field, 2) with initial NIHSS ≥6, between 2012-2017. Throughout this period, imaging policy was multimodal MRI (including DWI/GRE/MRA w/wo PWI) as the initial evaluation in all patients without contraindications, and multimodal CT (including CT with CTA, w/wo CTP) in the remainder. Achieved process times were compared with national recommendations for door-to-needle (45m, AHA/ASA Target Stroke) and door-to-puncture (90m, SVIN).

Results: Among 106 LVO thrombectomy patients, MRI was used in 62.3% and CT in 37.7%. MRI and CT patients were similar in age, 72.5 v 71.3y; severity (NIHSS) 16.4 v 18.2); and IV tPA door-to-needle times, median 45 vs 46 mins. However, MRI patients had longer onset-to-door times, median 100 vs 50 mins. From Jan 2012-Dec2014, in MRI vs CT groups, median door-to-imaging times were 20 min vs 18 min, p=0.88 and door-to-puncture times 102 vs 93 min, p=0.39. From Jan 2015-Dec2017, after the publication of the positive thrombectomy trials and endorsement of endovascular stroke treatment in US guidelines, in MRI vs CT groups, median door-to-imaging times were 17 min vs 17 min (p=0.93) and door-to-groin puncture 86 vs 71 min (p=0.02). There was no difference in functional outcome (mRS 0-2) between groups.

Conclusions: Optimized imaging processes enable acute AIS-LVO patients to be evaluated by multimodal MR with care speeds faster than national recommendations for door-to-needle and door-to-puncture times. While some patients have absolute contraindications to high magnetic fields, MRI, with its greater pathophysiologic insight, remains a highly viable primary imaging strategy in acute ischemic stroke patients.

Abstract WP62: Imaging With CT Perfusion Prior to Endovascular Therapy in STRATIS: Time to Rethink?

Background: Different neuroimaging triage strategies, including CT perfusion (CTP), are commonly used prior to endovascular therapy, often tailoring imaging approaches based on time from symptom onset. We analyzed whether the acquisition of CTP prior to endovascular therapy in STRATIS was related to clinical outcomes and if any possible link was noted based on time duration from symptom onset.

Methods: The STRATIS Core Lab analyzed all pre-procedural imaging in STRATIS, including the use of CTP. Acquisition of pre-procedural CTP was analyzed with respect to 90-day modified Rankin Score (mRS) clinical outcomes. Subgroup analyses explored whether this relationship was different in the 0-6 versus 6-8 hour interval from symptom onset.

Results: Among 984 subjects analyzed in STRATIS, 264 had pre-procedural CTP acquired by the imaging Core Laboratory. No association between CTP acquisition and mRS outcomes at 90 days was observed in the overall study cohort. However, among subjects treated over 6 hours from onset (n=119), a trend toward better outcomes was observed in those with CTP acquisition compared to those without (adjusted common odds ratio 1.86, p=0.092). This association was not present in subjects treated within 6 hours from onset (adjusted common odds ratio 1.10, p=0.498) (Figure).

Conclusions: Real-world data from STRATIS reveal that good clinical outcomes after endovascular therapy are not directly contingent on obtaining pre-procedural CTP. Subgroup analyses provide novel data that CTP may not be necessary 0-6 hours from onset, yet CTP may be linked with better outcomes in patients presenting after 6 hours.

Abstract TP73: Perfusion Values in Ischemic Core Depend on Time from Onset in Acute Stroke

Introduction: Infarct core in perfusion imaging is defined by rCBF regardless of time from onset.

Hypothesis: Perfusion values and optimal perfusion thresholds for ischemic core depend on onset-to-imaging time.

Methods: Prospectively collected date for consecutive patients treated with IV t-PA and/or endovascular thrombectomy was analyzed retrospectively. Inclusion criteria were (1) patients with ICA or M1 occlusion (2) underwent both DWI and PWI (3) onset time was clear. Ten places of ROI were set in the same place of ADC and PWI images. These ROI were separated into two groups; low ADC (ADC<620) and normal ADC area (ADC>620). In each area we investigated relationship between time to imaging from onset and each PWI values (rCBF, rCBV, MTT and Tmax). ROC curve analysis for ADC<620 was also performed and compared AUC of early (time from onset to imaging <180 min) and late group (>180 min).

Results: Sixty-six patients meet inclusion criteria and 660 ROI was analyzed. 164 ROI were low ADC and 496 ROI were normal ADC. There were statistically significant relationships between time from onset to imaging and rCBF (p=0.0051), rCBV (p<0.0001), MTT (p=0.0001) and Tmax (p<0.0001) in low ADC area. In contrast, no relationship was found in normal ADC area between time and each MRP values. ROC analysis for ADC<620 showed rCBF had the highest AUC. However, AUC in late group was significantly higher than early group (0.927 vs 0.850, p=0.0055) and optimal thresholds was different between early and late group.

Conclusions: Perfusion values on PWI depend on time only in low ADC area. The accuracy and optimal thresholds for ischemic core in perfusion image depend on time.

Abstract WP174: Frequency, Predicators, and Outcomes of Pre-Intervention Thrombus Migration in Patients With Acute Ischemic Stroke Due to Large Vessel Occlusion

Background: In patients presenting with acute ischemic stroke (AIS) due to large vessel occlusion (LVO), between initial CTA/MRA and catheter angiography performed for intervention, the occlusive thrombus may persist unchanged, fragment and migrate distally, or resolve completely, with or without bridging intravenous fibrinolytic treatment. The frequency, predictors, and outcomes of pre-intervention thrombus migration not been well delineated.

Methods: We analyzed a prospectively maintained registry of AIS-LVO patients at an academic medical center over a 2.8 year period (Dec 2014-Oct 2017). Comparing occlusion sites on arrival CTA/MRA with immediately following interventional angiogram, patients were classified as having: 1) thrombus persistence (TP), 2) thrombus migration (TM), or 3) thrombus resolution (TR).

Results: In the 220 patients, mean age was 70.7, 42.7% were female, NIHSS was 13.8, onset to first imaging was 156 minutes, and initial occlusion sites on MRA/CTA were: ICA-20.5%; MCA-67.3%; VA/BA-12.3%. Frequencies of thrombus evolution patterns were: TP-59.5%; TM-30.5%; TR-10.0%. On multivariate analysis, independent predictors of TM were: higher NIHSS (OR 1.06 per 1 pt), cardioembolic mechanism (OR 2.40), and longer time from last known well to first CTA/MRA imaging (OR 1.08 per 60 min). While rates of substantial reperfusion (TICI 2b-3) were similar (85.2% vs 83.7%), patients with TM rather than TP had lower rates of excellent reperfusion (TICI 2C-3), 24.1% vs 44.2%, p = 0.02. Symptomatic intracranial hemorrhage occurred more often in TM than TP, 17.9% vs 8.4%, p = 0.05. In multivariate analysis, TM was independently associated with reduced rates of good functional outcome (mRS 0-2), both at discharge (OR 0.41, 95% CI 0.19 to 0.90; p=0.03) and at 3 months (OR 0.43, 95% CI 0.19 to 0.94; p=0.03).

Conclusions: Early TM between initial noninvasive imaging and interventional angiography occurs in nearly one-third of patients, is paradoxically associated with poorer outcomes, including more symptomatic hemorrhage and reduced final functional independence. Better understanding of dynamic clot changes early after arrival and their effects on outcome may aid further development of reperfusion therapeutics.

Abstract WP13: Time to Treatment With Endovascular Reperfusion Therapy and Outcome From Acute Ischemic Stroke in the National US GWTG-Stroke Population

Background: Randomized trials have shown the benefit of endovascular reperfusion therapy (ERT) in acute ischemic stroke (AIS) is time dependent. However, generalizability to routine practice is uncertain; and modest sample sizes have limited characterization of the degree to which onset to treatment time influences outcome from ERT.

Methods: We analyzed data of 6756 AIS patients treated with ERT at 231 hospitals between January 2015 to December 2016. Multivariable logistic regression modeling was conducted to evaluate the independent impact of onset to puncture (OTP) and door to puncture (DTP) time on efficacy and safety outcomes.

Results: Among the 6756 patients, median age was 71, 51.2% were female, and NIHSS was 17 (IQR 12-22). Median OTP was 230m (IQR 170-305) and DTP 87m (IQR 62-116). Substantial reperfusion (TICI 2b-3) was in 85.9%. At discharge, 36.9% had independent ambulation, 27.8% were discharged to home, and 23.0% were functionally independent (mRS 0-2). Symptomatic intracranial hemorrhage (sICH) occurred in 6.7% and in-hospital mortality/hospice in 19.6%. For OTP, time-outcome relationships were nonlinear, with steeper slope in 0-270m than 271-480m (see Table and Figure). DTP showed a similar nonlinear time-outcome relationship, with steeper benefit decline in the 30-120m than 121-180m period.

Conclusions: In this national registry, faster endovascular therapy start, after onset and after arrival, was associated with better ambulation and functional independence at discharge, and reduced sICH and mortality/hospice. These findings support intensive efforts to accelerate hospital presentation and endovascular treatment in patients with stroke.

Abstract TP272: Air versus Ground Transport for Interhospital Transfer Prior to Endovascular Stroke Treatment

Introduction: Interhospital transfer for endovascular treatment of large vessel occlusion (LVO) stroke results in significant delays and worse outcomes. We hypothesized that interhospital patient transfer using air transport would result in shorter transit times compared to ground ambulance.

Methods: Subjects from the STRATIS registry that underwent interhospital transfer for endovascular treatment were separated by air transport vs. ground ambulance transport and analyzed by transfer distance. The primary endpoint was transfer-time, calculated as the time from imaging at the initial hospital to arrival at the treating hospital. Also assessed was travel-time, calculated as time of departure from the initial hospital to arrival at the treating hospital.

Results: There were 232 subjects from 41 sites. Mean transfer-time for all air subjects (n=118) was 147.1 min, and for all ground subjects (n=114) was 130.0 min (p=0.019). Mean travel-time was 45.0 min for air transport and 40.2 min for ground transport (p=0.239); though the average travel distance was longer for air (65.5 miles) vs. ground (27.6 miles; p<0.001). When analyzed by distance, there was no difference between air and ground transfer-time except transfers less than 20 miles, which favored ground transportation (154.4 min vs. 119.5 min; p=0.015; see table). The lack of advantage for air transport may be accounted for by the time between imaging and departure from the initial hospital (mean 89.4 vs. 101.6 min; p=0.075), reflecting additional logistics and/or reduced availability of air transport.

Conclusions: In this large, real-world study, interhospital transfer via air transport did not result in faster transfer times compared to ground ambulance. In fact, there was an advantage to ground transportation for distances of less than 20 miles. These results suggest that ground ambulance should routinely be used for interhospital transfer of stroke patients for travel less than 20 miles.

Selective middle cerebral artery occlusion in the rabbit: Technique and characterization with pathologic findings and multimodal MRI

BACKGROUND

A reliable animal model of ischemic stroke is vital for pre-clinical evaluation of stroke therapies. We describe a reproducible middle cerebral artery (MCA) embolic occlusion in the French Lop rabbit characterized with multimodal MRI and histopathologic tissue analysis.

NEW METHOD

Fluoroscopic-guided microcatheter placement was performed in five consecutive subjects with angiographic confirmation of MCA occlusion with autologous clot. Multimodal MRI was obtained prior to occlusion and up to six hours post after which repeat angiography confirmed sustained occlusion. The brain was harvested for histopathologic examination.

RESULTS

Angiography confirmed successful MCA catheterization and durable (>6 h) MCA occlusion in all animals. There was increase of ADC volume over time and variable final core volume presumably related to individual variation in collateral flow. FLAIR hyperintensity indicative of cytotoxic edema and parenchymal contrast enhancement reflective of blood brain barrier disruption was observed over time. Tissue staining of the ischemic brain showed edema and structural alterations consistent with infarction.

COMPARISON WITH EXISTING METHODS

This study describes a technique of selective catheterization and embolic occlusion of the MCA in the rabbit with MRI characterization of evolution of ischemia in the model.

CONCLUSIONS

We demonstrate the feasibility of a rabbit model of embolic MCA occlusion with angiographic documentation. Serial MR imaging demonstrated changes comparable to those observed in human ischemic stroke, confirmed histopathologically.

Meso-Scale Particle Image Velocimetry Studies of Neurovascular Flows In Vitro

Particle image velocimetry (PIV) is used in a wide variety of fields, due to the opportunity it provides for precisely visualizing and quantifying flows across a large spatiotemporal range. However, its implementation typically requires the use of expensive and specialized instrumentation, which limits its broader utility. Moreover, within the field of bioengineering, in vitro flow visualization studies are also often further limited by the high cost of commercially sourced tissue phantoms that recapitulate desired anatomical structures, particularly for those that span the mesoscale regime (i.e., submillimeter to millimeter length scales). Herein, we present a simplified experimental protocol developed to address these limitations, the key elements of which include 1) a relatively low-cost method for fabricating mesoscale tissue phantoms using 3-D printing and silicone casting, and 2) an open-source image analysis and processing framework that reduces the demand upon the instrumentation for measuring mesoscale flows (i.e., velocities up to tens of millimeters/second). Collectively, this lowers the barrier to entry for nonexperts, by leveraging resources already at the disposal of many bioengineering researchers. We demonstratethe applicability of this protocol within the context of neurovascular flow characterization; however, it is expected to be relevant to a broader range of mesoscale applications in bioengineering and beyond.

Penumbral imaging and functional outcome in patients with anterior circulation ischaemic stroke treated with endovascular thrombectomy versus medical therapy: a meta-analysis of individual patient-level data

BACKGROUND

CT perfusion (CTP) and diffusion or perfusion MRI might assist patient selection for endovascular thrombectomy. We aimed to establish whether imaging assessments of irreversibly injured ischaemic core and potentially salvageable penumbra volumes were associated with functional outcome and whether they interacted with the treatment effect of endovascular thrombectomy on functional outcome.

METHODS

In this systematic review and meta-analysis, the HERMES collaboration pooled patient-level data from all randomised controlled trials that compared endovascular thrombectomy (predominantly using stent retrievers) with standard medical therapy in patients with anterior circulation ischaemic stroke, published in PubMed from Jan 1, 2010, to May 31, 2017. The primary endpoint was functional outcome, assessed by the modified Rankin Scale (mRS) at 90 days after stroke. Ischaemic core was estimated, before treatment with either endovascular thrombectomy or standard medical therapy, by CTP as relative cerebral blood flow less than 30% of normal brain blood flow or by MRI as an apparent diffusion coefficient less than 620 μm²/s. Critically hypoperfused tissue was estimated as the volume of tissue with a CTP time to maximum longer than 6 s. Mismatch volume (ie, the estimated penumbral volume) was calculated as critically hypoperfused tissue volume minus ischaemic core volume. The association of ischaemic core and penumbral volumes with 90-day mRS score was analysed with multivariable logistic regression (functional independence, defined as mRS score 0-2) and ordinal logistic regression (functional improvement by at least one mRS category) in all patients and in a subset of those with more than 50% endovascular reperfusion, adjusted for baseline prognostic variables. The meta-analysis was prospectively designed by the HERMES executive committee, but not registered.

FINDINGS

We identified seven studies with 1764 patients, all of which were included in the meta-analysis. CTP was available and assessable for 591 (34%) patients and diffusion MRI for 309 (18%) patients. Functional independence was worse in patients who had CTP versus those who had diffusion MRI, after adjustment for ischaemic core volume (odds ratio [OR] 0·47 [95% CI 0·30-0·72], p=0·0007), so the imaging modalities were not pooled. Increasing ischaemic core volume was associated with reduced likelihood of functional independence (CTP OR 0·77 [0·69-0·86] per 10 mL, p_interaction=0·29; diffusion MRI OR 0·87 [0·81-0·94] per 10 mL, p_interaction=0·94). Mismatch volume, examined only in the CTP group because of the small numbers of patients who had perfusion MRI, was not associated with either functional independence or functional improvement. In patients with CTP with more than 50% endovascular reperfusion (n=186), age, ischaemic core volume, and imaging-to-reperfusion time were independently associated with functional improvement. Risk of bias between studies was generally low.

INTERPRETATION

Estimated ischaemic core volume was independently associated with functional independence and functional improvement but did not modify the treatment benefit of endovascular thrombectomy over standard medical therapy for improved functional outcome. Combining ischaemic core volume with age and expected imaging-to-reperfusion time will improve assessment of prognosis and might inform endovascular thrombectomy treatment decisions.

FUNDING

Medtronic.

Reperfusion after ischemic stroke is associated with reduced brain edema

Rapid revascularization is highly effective for acute stroke, but animal studies suggest that reperfusion edema may attenuate its beneficial effects. We investigated the relationship between reperfusion and edema in patients from the Echoplanar Imaging Thrombolysis Evaluation Trial (EPITHET) and Mechanical Retrieval and Recanalization of Stroke Clots Using Embolectomy (MR RESCUE) cohorts. Reperfusion percentage was measured as the difference in perfusion-weighted imaging lesion volume between baseline and follow-up (day 3-5 for EPITHET; day 6-8 for MR RESCUE). Midline shift (MLS) and swelling volume were quantified on follow-up MRI. We found that reperfusion was associated with less MLS (EPITHET: Spearman ρ = -0.46; P < 0.001, and MR RESCUE: Spearman ρ = -0.49; P < 0.001) and lower swelling volume (EPITHET: Spearman ρ = -0.56; P < 0.001, and MR RESCUE: Spearman ρ = -0.27; P = 0.026). Multivariable analyses performed in EPITHET and MR RESCUE demonstrated that reperfusion independently predicted both less MLS (ß coefficient = -0.056; P = 0.025, and ß coefficient = -0.38; P = 0.028, respectively) and lower swelling volumes (ß coefficient = -4.7; P = 0.007, and ß coefficient = -10.7; P = 0.009, respectively), after adjusting for age, sex, NIHSS, admission glucose and follow-up lesion size. Taken together, our data suggest that even modest improvement in perfusion is associated with less brain edema in EPITHET and MR RESCUE.

Relative cerebral blood volume is associated with collateral status and infarct growth in stroke patients in SWIFT PRIME

We aimed to evaluate how predefined candidate cerebral perfusion parameters correlate with collateral circulation status and to assess their capacity to predict infarct growth in patients with acute ischemic stroke (AIS) eligible for endovascular therapy. Patients enrolled in the SWIFT PRIME trial with baseline computed tomography perfusion (CTP) scans were included. RAPID software was used to calculate mean relative cerebral blood volume (rCBV) in hypoperfused regions, and hypoperfusion index ratio (HIR). Blind assessments of collaterals were performed using CT angiography in the whole sample and cerebral angiogram in the endovascular group. Reperfusion was assessed on 27-h CTP; infarct volume was assessed on 27-h magnetic resonance imaging/CT scans. Logistic and rank linear regression models were conducted. We included 158 patients. High rCBV ( p = 0.03) and low HIR ( p = 0.03) were associated with good collaterals. A positive association was found between rCBV and better collateral grades on cerebral angiography ( p = 0.01). Baseline and 27-h follow-up CTP were available for 115 patients, of whom 74 (64%) achieved successful reperfusion. Lower rCBV predicted a higher infarct growth in successfully reperfused patients ( p = 0.038) and in the endovascular treatment group ( p = 0.049). Finally, rCBV and HIR may serve as markers of collateral circulation in AIS patients prior to endovascular therapy.

CLINICAL TRIAL REGISTRATION

Unique identifier: NCT0165746.

eTICI reperfusion: defining success in endovascular stroke therapy

Background

Revascularization after endovascular therapy for acute ischemic stroke is measured by the Thrombolysis In Cerebral Infarction (TICI) scale, yet variability exists in scale definitions. We examined the degree of reperfusion with the expanded TICI (eTICI) scale and association with outcomes in the HERMES collaboration of recent endovascular trials.

Methods

The HERMES Imaging Core, blind to all other data, evaluated angiography after endovascular therapy in HERMES. A battery of TICI scores (mTICI, TICI, TICI2C) was used to define reperfusion of the initial target occlusion defined by non-invasive imaging and conventional angiography.

Results

Angiography of 801 subjects was available, including 797 defined by non-invasive imaging (154 internal carotid artery (ICA), 583 M1, 60 M2) and 748 by conventional angiography (195 ICA, 459 M1, 94 M2). Among 729 subjects in whom the reperfusion grade could be established, using eTICI (3=100%, 2C=90–99%, 2b67=67–89%, 2b50=50–66%) of the conventional angiography target occlusion, there were 63 eTICI 3 (9%), 166 eTICI 2c (23%), 218 eTICI 2b67 (30%), 103 eTICI 2b50 (14%), 100 eTICI 2a (14%), 19 eTICI 1 (3%), and 60 eTICI 0 (8%). Modified Rankin Scale shift analyses from baseline to 90 days showed that increasing TICI grades were linked with better outcomes, with significant distinctions between TICI 0/1 versus 2a (p=0.028), 2a versus 2b50 (p=0.017), and 2b50 versus 2b67 (p=0.014).

Conclusions

The benefit of endovascular therapy in HERMES was strongly associated with increasing degrees of reperfusion defined by eTICI. The eTICI metric identified meaningful distinctions in clinical outcomes and may be used in future studies and routine practice.

Regional Contributions to Poststroke Disability in Endovascular Therapy

Background and Purpose

The relative contribution of each Alberta Stroke Program Early CT Score (ASPECTS) region to poststroke disability likely varies across regions. Determining the relative weights of each ASPECTS region may improve patient selection for endovascular stroke therapy (EST).

Methods

In the combined Solitaire Flow Restoration with the Intention for Thrombectomy (SWIFT), Solitaire Flow Restoration Thrombectomy for Acute Revascularization (STAR), and Solitaire Flow Restoration with the Intention for Thrombectomy as Primary Endovascular Treatment (SWIFT PRIME) databases, we identified patients treated with the Solitaire stent retriever. Using 24-h CT scan, a multivariate ordinal regression was used to determine the relative contribution of each ASPECTS region to clinical outcome separately in each hemisphere. The coefficients from the regression were used to create a weighted ASPECTS (wASPECTS), which was compared with the original ASPECTS to predict 90-day modified Rankin Scale disability outcomes in an independent validation cohort.

Results

Among 342 patients treated with EST, the average age was 67 years, 57% were female, and the median National Institutes of Health Stroke Scale (NIHSS) score was 17 (IQR 13-20). The median ASPECTS at presentation was 8 (IQR 7-10). The most commonly involved ASPECTS regions on 24-h CT were the lentiform nuclei (70%), insula (55%), and caudate (52%). In multivariate analysis, preservation of M6 (β = 9.7) and M4 (β = 4.4) regions in the right hemisphere was most strongly predictive of good outcome. For the left hemisphere, M6 (β = 5.5), M5 (β = 4.1), and M3 (β = 3.1) generated the greatest parameter estimates, though they did not reach statistical significance. A wASPECTS incorporating all 20 parameter estimates resulted in improved discrimination against the original ASPECTS in the independent cohort (C-statistic 0.78 vs. 0.67, right hemisphere).

Conclusions

For both right and left hemisphere, preservation of the high cortical regions was more strongly associated with improved outcomes compared to the deep regions. Our findings support taking into consideration the location and relative weightings of the involved ASPECTS regions when evaluating a patient for EST.

Impact of Anesthetic Management on Safety and Outcomes Following Mechanical Thrombectomy for Ischemic Stroke in SWIFT PRIME Cohort

Background and purpose: The optimal anesthetic management of acute ischemic stroke patients during mechanical thrombectomy (MT) remains controversial. In this post-hoc analysis, we investigated the impact of anesthesia type on clinical outcomes in patients included in SWIFT PRIME trial.

Methods: Ninety-seven patients treated with MT were included. Patients treated in centers with general anesthesia (GA) policy (n = 32) were compared with those treated in centers with conscious sedation (CS) policy (n = 65). Primary outcomes studied included times to treatment initiation (TTI), rates of successful recanalization (TICI 2b/3), and functional independence (mRS 0–2 at 90 days). Secondary outcomes were adverse events, lowest systolic and diastolic blood pressures (LSBP and LDBP) during MT. Univariate analysis and multivariate regression logistic modeling were conducted.

Results: The GA-policy and CS-policy groups presented comparable TTI (94 ± 36 min vs. 102 ± 48 min; p = 0.44), rates of TICI 2b/3 recanalization (22/32 [68.8%] vs. 51/65 [78.5%]; p = 0.32). CS-policy was associated to higher rate of functional independence than GA-policy, but the difference was not significant (43/65 [66.2%] vs. 16/32 [50.0%]; p = 0.18). GA-policy patients had a higher rate of postoperative pneumonia (11/32 [34.4%] vs. 8/65 [12.3%]; p = 0.02) and lower LSBP (110 [30,160] mmHg vs. 119 [77,170] mmHg; p = 0.03) and LDBP (55 (15,75) mmHg vs. 67 [40,121]; p < 0.001). When corrected for differences in baseline characteristics, GA-policy was associated with lower rate of functional independence (OR 0.32; p = 0.05). A 10-point increase in perprocedural LDBP was associated with an increased likelihood of favorable outcome (OR 1.51; p = 0.01).

Conclusions: GA-policy for MT presented comparable TTI and rates of successful revascularization to CS-policy. However, GA-policy was associated with lower rates of functional independence and with higher incidence of perprocedural hypotension and postoperative pneumonia.

Clinical Trial Registration: URL—http://www.clinicaltrials.gov. Unique identifier: NCT01657461

The Frequency of Substantial Salvageable Penumbra in Thrombectomy-ineligible Patients with Acute Stroke

BACKGROUND AND PURPOSE

Endovascular therapy (ET) has become the standard of care for selected patients with acute ischemic stroke (AIS) due to large vessel occlusion (LVO). However, many LVO or medium vessel occlusion (MVO) patients are ineligible for ET, including some who harbor salvageable tissues. To develop complementary therapies for these patients, it is important to delineate their prevalence, clinical features, and outcomes.

METHODS

In a prospectively maintained database, we reviewed consecutive AIS patients between December 2015 and September 2016. Based on the first multimodal computed tomography or magnetic resonance imaging, patients were categorized as having substantial penumbra if perfusion lesion volume (Tmax >6 seconds) exceeded ischemic core volume (relative cerebral blood flow <30% on CT perfusion or apparent diffusion coefficient <620 on diffusion weighted image) by ≥20%.

RESULTS

Among 174 consecutive AIS patients presenting within 24 hours of last known well time, 29 (17%) had LVO or MVO and substantial penumbra, but were deemed ET ineligible. Among these patients, mean age was 81 (±13), 45% were female, and median National Institute of Health Stroke Scale score was 11 (interquartile range [IQR]: 5-19). The most common reasons for not pursuing ET were: distal occlusion (28%), mild neurologic deficit (16%), and temporally advanced core injury (16%). Ischemic core volume was 20 mL (±31), penumbral volume was 54 mL (±63), and mismatch ratio median was 5.6 (IQR: 2-infinite). Severe disability or death at discharge (modified Rankin scale: 4-6) occurred in 72% of the patients.

CONCLUSION

Even in the modern stent retriever era, 1 in 6 AIS patients presents with substantial penumbra judged not appropriate for ET. This population may benefit from the development of alternative therapies, including collateral enhancement, neuroprotection, and thrombectomy devices deployable in distal arteries.

The Meningioma Vascularity Index: a volumetric analysis of flow voids to predict intraoperative blood loss in nonembolized meningiomas

OBJECTIVEMeningiomas that appear hypervascular on neuroimaging could be amenable to preoperative embolization. However, methods for measuring hypervascularity have not been described, nor has the benefit of preoperative embolization been adjudicated. The objective of this study was to show a relationship between flow void volume (measured on MRI) and intraoperative estimated blood loss (EBL) in nonembolized meningiomas.METHODSThe authors performed volumetric analyses of 51 intracranial meningiomas (21 preoperatively embolized) resected at their institution. Through the use of image segmentation software and a voxel-based segmentation method, flow void volumes were measured on T2-weighted MR images. This metric was named the Meningioma Vascularity Index (MVI). The primary outcomes were intraoperative EBL and perioperative blood transfusion.RESULTSIn the nonembolized group, the MVI correlated with intraoperative EBL when controlling for tumor volume (r = 0.55, p = 0.002). The MVI also correlated with perioperative blood transfusion (point-biserial correlation [rpb] = 0.57, p = 0.001). A greater MVI was associated with an increased risk of blood transfusion (odds ratio [OR] 5.79, 95% confidence interval [CI] 1.15-29.15) and subtotal resection (OR 7.64, 95% CI 1.74-33.58). In the embolized group, those relationships were not found. There were no significant differences in MVI, intraoperative EBL, or blood transfusion across groups.CONCLUSIONSThis study clearly shows a relationship between MVI and intraoperative EBL in nonembolized meningiomas when controlling for tumor volume. The MVI is a potential biomarker for tumors that would benefit from embolization.

A review of the diagnosis and management of vertebral basilar (posterior) circulation disease

We have reviewed the English literature published in the last 70 years on Diseases of the Vertebral Basilar Circulation, or Posterior Circulation Disease (PCD). We have found that errors have been made in the conduct and interpretation of these studies that have led to incorrect approaches to the management of PCD. Because of the difficulty in evaluating the PC, the management of PCD has been incorrectly applied from anterior circulation disease (ACD) experience to PCD. PCD is a common form of stroke affecting 20-40% patients with stroke. Yet, the evidence is strong that the Anterior Circulation (AC) and Posterior Circulations (PC) differ in their pathology, in their clinical presentations, in the rapidity of development of symptoms, in optimal imaging methods, and in available treatments. There appears to be two categories of patients who present with PCD. The first, acute basilar artery occlusion has a more rapid onset. The diagnosis must be made quickly and if imaging proves a diagnosis of Basilar Artery Occlusion (BAO), the treatment of choice is Interventional removal of the basilar artery thrombosis or embolus. The second category of PCD and the most commonly seen PCD disease process presents with non-specific symptoms and early warnings of PCD that now can be related to ischemic events in the entire PC vessels. These warning symptoms and signs occur much earlier than those in the AC. IA angiography is still the gold standard of diagnosis and is superior in definition to MR and CT angiography which are commonly used as a convenient screening imaging tool to evaluate PCD but are both inferior to IA angiography in definition for lesions below 3-4 mm. In at least two reported studies 7T MR angiography appears superior to other imaging modalities and will become the gold standard of imaging of PCD in the future. Medical treatments applied to the ACD have not been proven of value in specific forms of PCD. Interventional therapy was promising but of unproven value in Randomized Controlled Trials (RCT) except for the treatment of Basilar Artery Occlusion (BAO). Surgical revascularization has been proved to be highly successful in patients, who are refractory to medical therapy. These studies have been ignored by the scientific community basically because of an incorrect interpretation of the flawed EC-IC Bypass Trial in 1985 as applying to all stroke patients. Moreover, the EC-IC Bypass Study did not include PCD patients in their study population, but the study results were extrapolated to patients with PCD without any scientific basis. This experience led clinicians to an incorrect bias that surgical treatments are of no value in PCD. Thus, incorrectly, surgical treatments of PCD have not been considered among the therapeutic possibilities for PCD. QMRA is a new quantitative MR technique that measures specific blood flow in extra and intracranial vessels. QMRA has been used to select those patients who may benefit from medical, or interventional, or surgical treatment for PCD based on flow determinations with a high success rate. QMRA accurately predicts the flows in many large and small vessels in the PC and AC and clearly indicates that both circulations are intimately related. From medical and surgical studies, the longer one waits for surgical treatment the higher the risk of a poor outcome results. This observation becomes obvious when the rapidity of development of PCD is compared with ACD. Recent advances in endovascular therapy in the treatment of acute basilar thrombosis is a clear sign that early diagnosis and treatment of PCD will reduce the morbidity and mortality of these diseases. In this review it is evident that there are multiple medical and surgical treatments for PCD depending upon the location of the lesion(s) and the collateral circulation demonstrated. It is clear that the AC and PC have significant differences. With the exception of the large population studies from Oxford England, the reported studies on the management of PCD in the literature represent small selected subsets of the universe of PC diseases, the information from which is not generalizable to the universe of PCD patients. At this point in the history of PCD, there are not large enough databases of similar patients to provide a basis for valid randomized studies, with the exception of the surgical studies. Thus, a high index of suspicion of the early warning symptoms of PCD should lead to a rapid individual clinical assessment of patients selecting those with PCD. Medical, interventional, and/or surgical treatments should be chosen based on knowledge presented in this review. Recording the results in a national Registry on a continuing basis will provide the data that may help advance the management of PCD based on larger data bases of well documented patient information to guide the selection of future therapies for PCD treatments. It is also clear that the management of patients within the complex of diseases that comprise PCD should be performed in centers with expertise in the imaging, medical, interventional and surgical approaches to diseases of the PCD.

Apparent Diffusion Coefficient Signal Intensity Ratio Predicts the Effect of Revascularization on Ischemic Cerebral Edema

BACKGROUND

Apparent diffusion coefficient (ADC) imaging is a biomarker of cytotoxic injury that predicts edema formation and outcome after ischemic stroke. It therefore has the potential to serve as a "tissue clock" to describe the extent of ischemic injury and potentially predict response to therapy. The goal of this study was to determine the relationship between baseline ADC signal intensity, revascularization, and edema formation.

METHODS

We examined the ADC signal intensity ratio (ADCr) of the stroke lesion (defined as the baseline DWI hyperintense region) compared to the contralateral normal hemisphere in 65 subjects from the Mechanical Retrieval and Recanalization of Stroke Clots Using Embolectomy trial. The associations between ADCr, neurologic outcome, and cerebral edema were examined. Finally, we explored the interaction between baseline ADCr and vessel recanalization at day 7 on post-stroke edema.

RESULTS

We found that lower initial ADCr was associated with a worse outcome on the modified Rankin Scale (mRS) at 90 days (52.2% of those with ADCr <64% were mRS 5-6 vs. 19.1% with ADCr ≥64%, p = 0.006). Those subjects with reconstitution of flow distal to the initial vessel occlusion showed greater normalization of ADCr on follow-up scan (increase in ADCr of 16.4 ± 2.07 vs. 1.99 ± 4.33%, p = 0.0039). In those patients with low baseline ADCr, successful revascularization was associated with reduced edema (median swelling volume 164 mL [interquartile range (IQR) 53.3-190 mL] vs. 20.7 mL [IQR 3.20-55.1 mL], p = 0.024).

CONCLUSIONS

This study reaffirms the association of ADCr with outcome after stroke, supports the idea that reperfusion may attenuate rather than enhance post-stroke edema, and indicates that the degree of edema with and without revascularization may be predicted by ADCr.

ASPECTS-based reperfusion status on arterial spin labeling is associated with clinical outcome in acute ischemic stroke patients

The purpose of this study was to develop and evaluate a scoring system for assessing reperfusion status based on arterial spin labeled (ASL) perfusion MRI in acute ischemic stroke (AIS) patients receiving thrombolysis and/or endovascular treatment. Pseudo-continuous ASL with background suppressed 3D GRASE was acquired along with DWI in 90 patients within 24 h post-treatment. An automatic reperfusion scoring system (auto-RPS) was devised based on the Alberta Stroke Program Early CT Score (ASPECTS) template, and compared with manual RPS and DWI-ASPECTS. TICI (thrombolysis in cerebral infarction) scores were graded in 48 patients who received endovascular treatment. Favorable outcomes were defined by a modified Rankin Scale score of 0-2 at three months. Auto-RPS was positively correlated with DWI-ASPECTS (ρ = 0.6, P < 0.001) and was on average 1 point lower than DWI-ASPECTS ( P < 0.001). The area under the receiver operating characteristic curve for discriminating poor functional outcome (n = 90) was 0.75 (95% CI, 0.64-0.86) for manual RPS, 0.85 (95% CI, 0.76-0.94) for auto-RPS, and 0.81 (95% CI, 0.71-0.90) for DWI-ASPECTS. Multiple logistic regression analysis in the TICI-graded patients (n = 48) showed that auto-RPS is highly associated with functional outcome (OR = 25.2, 95% CI 4.02-496, P < 0.01). Post treatment auto-RPS within 24 h provides a useful tool to predict functional outcome in AIS patients.