Radiographic Characteristics of Mild Ischemic Stroke Patients With Visible Intracranial Occlusion: The INTERRSeCT Study

Stroke ◽  
2021 ◽  
Author(s):  
H. Lee Lau ◽  
Hannah Gardener ◽  
Shelagh B. Coutts ◽  
Vasu Saini ◽  
Thalia S. Field ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Scale Score ◽  
Cerebral Artery ◽  
Odds Ratio ◽  
Arterial Occlusion ◽  
National Institutes Of Health ◽  
Collateral Flow ◽  
Residual Flow ◽  
Intravenous Alteplase ◽  
Multicenter Prospective Study

Background and Purpose: Early neurological deterioration occurs in one-third of mild strokes primarily due to the presence of a relevant intracranial occlusion. We studied vascular occlusive patterns, thrombus characteristics, and recanalization rates in these patients. Methods: Among patients enrolled in INTERRSeCT (Identifying New Approaches to Optimize Thrombus Characterization for Predicting Early Recanalization and Reperfusion With IV Alteplase and Other Treatments Using Serial CT Angiography), a multicenter prospective study of acute ischemic strokes with a visible intracranial occlusion, we compared characteristics of mild (National Institutes of Health Stroke Scale score, ≤5) to moderate/severe strokes. Results: Among 575 patients, 12.9% had a National Institutes of Health Stroke Scale score ≤5 (median age, 70.5 [63–79]; 58% male; median National Institutes of Health Stroke Scale score, 4 [2–4]). Demographics and vascular risk factors were similar between the two groups. As compared with those with a National Institutes of Health Stroke Scale score >5, mild patients had longer symptom onset to assessment times (onset to computed tomography [240 versus 167 minutes] and computed tomography angiography [246 versus 172 minutes]), more distal occlusions (M3, anterior cerebral artery and posterior cerebral artery; 22% versus 6%), higher clot burden score (median, 9 [6–9] versus 6 [4–9]), similar favorable thrombus permeability (residual flow grades I–II, 21% versus 19%), higher collateral flow (9.1 versus 7.6), and lower intravenous alteplase treatment rates (55% versus 85%). Mild patients were more likely to recanalize (revised arterial occlusion scale score 2b/3, 45%; 49% with alteplase) compared with moderate/severe strokes (26%; 29% with alteplase). In an adjusted model for sex, alteplase, residual flow, and time between the two vessel imagings, intravenous alteplase use (odds ratio, 3.80 [95% CI, 1.11–13.00]) and residual flow grade (odds ratio, 8.70 [95% CI, 1.26–60.13]) were associated with successful recanalization among mild patients. Conclusions: Mild strokes with visible intracranial occlusions have different vascular occlusive patterns but similar thrombus permeability compared with moderate/severe strokes. Higher thrombus permeability and alteplase use were associated with successful recanalization, although the majority do not recanalize. Randomized controlled trials are needed to assess the efficacy of new thrombolytics and endovascular therapy in this population.

scholarly journals Treatment and Outcome in Stroke Patients With Acute M2 Occlusion and Minor Neurological Deficits

Stroke ◽  
2021 ◽  
Author(s):  
Tomas Dobrocky ◽  
Eike I. Piechowiak ◽  
Bastian Volbers ◽  
Nedelina Slavova ◽  
Johannes Kaesmacher ◽  
...  
Keyword(s):  
Middle Cerebral Artery ◽  
Scale Score ◽  
Cerebral Artery ◽  
Odds Ratio ◽  
Adjusted Odds Ratio ◽  
National Institutes Of Health ◽  
Neurological Deficits ◽  
Minor Stroke ◽  
Modified Rankin Scale ◽  
Stroke Patients

Background and Purpose: Treatment in stroke patients with M2 segment occlusion of the middle cerebral artery presenting with mild neurological deficits is a matter of debate. The main purpose was to compare the outcome in patients with a minor stroke and a M2 occlusion. Methods: Consecutive intravenous thrombolysis (IVT) eligible patients admitted to the Bernese stroke center between January 2005 and January 2020 with acute occlusion of the M2 segment and National Institutes of Health Stroke Scale score ≤5 were included. Outcome was compared between IVT only versus endovascular therapy (EVT) including intra-arterial thrombolysis and mechanical thrombectomy (MT; ±IVT) and between IVT only versus MT only. Results: Among 169 patients (38.5% women, median age 70.2 years), 84 (49.7%) received IVT only and 85 (50.3%) EVT (±IVT), the latter including 39 (45.9%) treated with MT only. Groups were similar in sex, age, vascular risk factors, event cause, or preevent independency. Compared with IVT only, there was no difference in favorable outcome (modified Rankin Scale score, 0−2) for EVT (adjusted odds ratio, 0.96; adjusted P =0.935) or for MT only (adjusted odds ratio, 1.12; adjusted P =0.547) groups. Considering only patients treated after 2015, there was a significantly better 3-month modified Rankin Scale shift (adjusted P =0.032) in the EVT compared with the IVT only group. Conclusions: Our study demonstrates similar effectiveness of IVT only versus EVT (±IVT), and of IVT only versus MT only in patients with peripheral middle cerebral artery occlusions and minor neurological deficits and indicates a possible benefit of EVT considering only patients treated after 2015. There is an unmet need for randomized controlled trials in this stroke field, including imaging parameters, and more sophisticated evaluation of National Institutes of Health Stroke Scale score subitems, neurocognition, and quality of life neglected by the standard outcome scales such as modified Rankin Scale and National Institutes of Health Stroke Scale score.

scholarly journals Prevalence and Outcomes of Medium Vessel Occlusions With Discrepant Infarct Patterns

Stroke ◽  
2020 ◽  
Vol 51 (9) ◽  
pp. 2817-2824
Author(s):  
Johanna M. Ospel ◽  
Petra Cimflova ◽  
Martha Marko ◽  
Arnuv Mayank ◽  
Moiz Hafeez ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Scale Score ◽  
Cerebral Artery ◽  
Odds Ratio ◽  
Adjusted Odds Ratio ◽  
Modified Rankin Scale ◽  
Excellent Outcome ◽  
Good Outcome

Background and Purpose: The prognosis of medium vessel occlusions (MeVOs), that is, M2/3 middle cerebral artery, A2/3 anterior cerebral artery, and P2/3 posterior cerebral artery occlusions, is generally better compared with large vessel occlusions, since brain ischemia is less extensive. However, in some MeVO patients, infarcts are seen outside the territory of the occluded vessel (MeVO with discrepant infarcts). This study aims to determine the prevalence and clinical impact of discrepant infarct patterns in acute ischemic stroke due to MeVO. Methods: We pooled data of MeVO patients from INTERRSeCT (Identifying New Approaches to Optimize Thrombus Characterization for Predicting Early Recanalization and Reperfusion With IV Alteplase and Other Treatments Using Serial CT Angiography) and PRove-IT (Precise and Rapid Assessment of Collaterals Using Multi-Phase CTA in the Triage of Patients With Acute Ischemic Stroke for IA Therapy)—2 prospective cohort studies of patients with acute ischemic stroke. The combination of occlusion location on baseline computed tomography angiography and infarct location on follow-up computed tomography/magnetic resonance imaging was used to identify MeVOs with discrepant infarct patterns. Two definitions for discrepant infarcts were applied; one was more restrictive and purely based on infarct patterns of the basal ganglia, whereas the second one took cortical infarct patterns into account. Clinical outcomes of patients with versus without discrepant infarcts were summarized using descriptive statistics. Logistic regression was performed to obtain adjusted effect size estimates for the association of discrepant infarcts and good outcome, defined as a modified Rankin Scale score of 0 to 2, and excellent outcome (modified Rankin Scale score 0–1). Results: Two hundred sixty-two patients with MeVO were included in the analysis. The prevalence of discrepant infarcts was 39.7% (definition 1) and 21.0% (definition 2). Patients with discrepant infarcts were less likely to achieve good outcome (definition 1: adjusted odds ratio, 0.48 [95% CI, 0.25–0.91]; definition 2: adjusted odds ratio, 0.47 [95% CI, 0.22–0.99]). When definition 1 was applied, patients with discrepant infarcts were also less likely to achieve excellent outcome (definition 1: adjusted odds ratio, 0.55 [95% CI, 0.31–0.99]; definition 2: adjusted odds ratio, 0.62 [95% CI, 0.31–1.25]). Conclusions: MeVO patients with discrepant infarcts are common, and they are associated with more severe deficits and poor outcomes.

scholarly journals Mechanical Thrombectomy in Basilar Artery Occlusion

Stroke ◽  
2020 ◽  
Vol 51 (7) ◽  
pp. 2045-2050 ◽  
Author(s):  
Hyo Sung Kwak ◽  
Jung Soo Park
Keyword(s):  
Computed Tomography ◽  
Endovascular Treatment ◽  
Scale Score ◽  
Basilar Artery ◽  
Odds Ratio ◽  
Mechanical Thrombectomy ◽  
Artery Occlusion ◽  
Posterior Circulation ◽  
National Institutes Of Health ◽  
Basilar Artery Occlusion

Background and Purpose: Basilar artery occlusion (BAO) is associated with a high risk of disability and mortality. The objective of this study was to investigate prognostic factors in patients with acute basilar artery occlusion treated with mechanical thrombectomy, focusing on collateral status and recanalization time from symptom onset. Methods: Eligible patients from January 2012 to October 2019 who underwent endovascular treatment due to acute BAO were reviewed. The baseline posterior circulation collateral status was assessed with the basilar artery on computed tomography angiography score and posterior circulation collateral score. Good outcomes were defined as a modified Rankin Scale score of ≤2 at 3 months and successful recanalization as Thrombolysis in Cerebral Infarction grades 2b, 3. The associations between baseline and clinical parameters and favorable outcomes were evaluated with logistic regression. Results: Our sample included a total of 81 eligible patients (49 males, mean age 70.3 years) with a median baseline and discharge National Institutes of Health Stroke Scale score of 12. Patients with good outcomes showed a lower baseline National Institutes of Health Stroke Scale score, a greater proportion of distal BAO, and a higher basilar artery on computed tomography angiography and posterior circulation collateral score ( P <0.001). According to subgroup analysis of patients within and over 6 or 12 hours, the time from symptom onset to recanalization was not correlated with good outcomes. Multivariable logistic analysis showed baseline National Institutes of Health Stroke Scale <15 (odds ratio, 8.49 [95% CI, 2.01–35.82]; P =0.004), posterior circulation collateral score ≥6 (odds ratio, 3.79 [95% CI, 1.05–13.66]; P =0.042), and distal BAO (odds ratio, 3.67 [95% CI, 1.10–12.26]; P =0.035) were independent predictors of good outcomes. Conclusions: This study suggested that good collateral circulation and distal BAO are independent predictors of clinical outcome after endovascular treatment in patients with acute BAO. In particular, patients with good initial collateral status and distal BAO may consider endovascular treatment even if the treatment is started beyond the standard time limits.

scholarly journals Time Matters

Stroke ◽  
2020 ◽  
Vol 51 (6) ◽  
pp. 1766-1771 ◽  
Author(s):  
Manuel Requena ◽  
Marta Olivé ◽  
Álvaro García-Tornel ◽  
Noelia Rodríguez-Villatoro ◽  
Matías Deck ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Endovascular Treatment ◽  
Functional Outcome ◽  
Scale Score ◽  
Odds Ratio ◽  
Hemorrhagic Transformation ◽  
National Institutes Of Health ◽  
Retrospective Case ◽  
Good Functional Outcome ◽  
Angiography Suite

Background and Purpose— Direct transfer to angiography-suite (DTAS) protocol is a promising measure to improve onset to recanalization time in patients who undergo endovascular treatment. The magnitude of the improvement of good outcome rates in function of time depends of several factors. We aim to analyze the benefit of DTAS according to time from symptom onset. Methods— Retrospective case-control study of 174 consecutive DTAS cases matched with 175 patients initially transferred to computed tomography (directly transferred to computed tomography) from February 2016 to June 2019. To obtain comparable groups on admission, cases and controls were matched by occlusion location, age (±2 years), baseline National Institutes of Health Stroke Scale score (±2 points), and time from symptoms onset to hospital arrival (±30 minutes). We analyzed the rate of good functional outcome at 3 months (modified Rankin Scale score, 0–2) and safety variables stratified in less or more than 3 hours from onset to arrive. Results— There were no significant differences regarding age, sex, or baseline National Institutes of Health Stroke Scale score. Median door-to-groin time was shorter in the DTAS patients (16 [3–21] minutes versus 70 [41.5–98.5]; P <0.01). DTAS patients presented lower National Institutes of Health Stroke Scale score at 24 hours (9 [3.5–17] versus 14 [5–19]; P =0.01) and a lower rate of symptomatic hemorrhagic transformation (4.6% versus 10.9%, P <0.03). At 90 days, DTAS patients had a higher rate of good functional outcome (43% versus 29%; odds ratio, 1.81 [95% CI, 1.14–2.87]; P =0.01). Better outcome in DTAS was observed in patients admitted in the 0 to 3 hours form onset window (n=156, odds ratio 2.63 [95% CI, 1.31–5.28]; P <0.01), but not in patients admitted in the 3 to 6 hours window (n=193, odds ratio, 1.37 [95% CI, 0.72–2.60]; P =0.2). Conclusions— DTAS seems a feasible and safe strategy to improve functional outcome in patients who undergo endovascular treatment mainly within 3 hours from symptoms onset.

scholarly journals Thrombus Migration and Fragmentation After Intravenous Alteplase Treatment

Stroke ◽  
2021 ◽  
Vol 52 (1) ◽  
pp. 203-212
Author(s):  
Tomoyuki Ohara ◽  
Bijoy K. Menon ◽  
Fahad S. Al-Ajlan ◽  
MacKenzie Horn ◽  
Mohamed Najm ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Carotid Artery ◽  
Clinical Outcome ◽  
Odds Ratio ◽  
Adjusted Odds Ratio ◽  
Internal Carotid ◽  
Artery Occlusion ◽  
Intravenous Alteplase ◽  
Over Time

Background and Purpose: There is interest in what happens over time to the thrombus after intravenous alteplase. We study the effect of alteplase on thrombus structure and its impact on clinical outcome in patients with acute stroke. Methods: Intravenous alteplase treated stroke patients with intracranial internal carotid artery or middle cerebral artery occlusion identified on baseline computed tomography angiography and with follow-up vascular imaging (computed tomography angiography or first run of angiography before endovascular therapy) were enrolled from INTERRSeCT study (Identifying New Approaches to Optimize Thrombus Characterization for Predicting Early Recanalization and Reperfusion With IV Alteplase and Other Treatments Using Serial CT Angiography). Thrombus movement after intravenous alteplase was classified into complete recanalization, thrombus migration, thrombus fragmentation, and no change. Thrombus migration was diagnosed when occlusion site moved distally and graded according to degrees of thrombus movement (grade 0–3). Thrombus fragmentation was diagnosed when a new distal occlusion in addition to the primary occlusion was identified on follow-up imaging. The association between thrombus movement and clinical outcome was also evaluated. Results: Among 427 patients in this study, thrombus movement was seen in 54% with a median time of 123 minutes from alteplase administration to follow-up imaging, and sub-classified as marked (thrombus migration grade 2–3 + complete recanalization; 27%) and mild to moderate thrombus movement (thrombus fragmentation + thrombus migration grade 0–1; 27%). In patients with proximal M1/internal carotid artery occlusion, marked thrombus movement was associated with a higher rate of good outcome (90-day modified Rankin Scale, 0–2) compared with mild to moderate movement (52% versus 27%; adjusted odds ratio, 5.64 [95% CI, 1.72–20.10]). No difference was seen in outcomes between mild to moderate thrombus movement and no change. In M1 distal/M2 occlusion, marked thrombus movement was associated with improved 90-day good outcome compared with no change (70% versus 56%; adjusted odds ratio, 2.54 [95% CI, 1.21–5.51]). Conclusions: Early thrombus movement is common after intravenous alteplase. Marked thrombus migration leads to good clinical outcomes. Thrombus dynamics over time should be further evaluated in clinical trials of acute reperfusion therapy.

scholarly journals Effects of Adenosine and 2-Chloroadenosine on Cerebral Collateral Vessels

1995 ◽  
Vol 15 (6) ◽  
pp. 1075-1081 ◽  
Author(s):  
Michael G. Muhonen ◽  
Christopher M. Loftus ◽  
Donald D. Heistad
Keyword(s):  
Blood Flow ◽  
Cerebral Artery ◽  
Topical Application ◽  
Collateral Circulation ◽  
Arterial Occlusion ◽  
Collateral Flow ◽  
Cortical Layers ◽  
Area At Risk ◽  
Collateral Vessels ◽  
Cerebral Vasodilator

Adenosine is a potent cerebral vasodilator. We tested the hypothesis that dilatation of collateral vessels in cerebrum, in response to topical adenosine and 2-chloroadenosine (2-CAD), would increase blood flow to collateral-dependent cerebrum. In dogs anesthetized with halothane, a branch of the middle cerebral artery (MCA) was occluded proximally and cannulated distally. The collateral-dependent area at risk for infarction was perfused from a reservoir with microsphere-free blood, and blood flow to normal cerebrum and to cerebrum dependent on collateral flow was measured with radioactive microspheres injected into the left ventricle through a femoral artery catheter. Perfusion through the cannulated MCA branch was stopped, and flow to normal and collateral-dependent cerebrum was measured after adenosine (10−2 M) or 2-CAD (10−4 M) was added to the superfusate over the cerebrum. In normal cerebrum, topical application of adenosine increased flow to outer but not inner layers. Topical application of adenosine had little effect on flow to collateral-dependent tissue. In normal cerebrum, 2-CAD increased flow to outer layers, whereas flow to inner layers tended to increase. During 2-CAD, flow to outer cortical layers of collateral-dependent cerebrum increased from 140 ± 20 ml/100 g/min (mean ± SD) to 231 ± 68, whereas flow to the inner collateral-dependent tissue did not change. The findings indicate that, after occlusion of a cerebral artery, topical 2-CAD increases blood flow to outer layers of collateral-dependent and normal cerebrum. The findings suggest also that, after arterial occlusion, collateral circulation to cerebrum has dilator reserve, and flow to tissues that are dependent on collaterals may be augmented.

scholarly journals Value of computed tomography angiographic collateral status in prediction of malignant middle cerebral artery infarction

2020 ◽  
pp. 4-20
Author(s):  
Sasitorn Petcharunpaisan ◽  
Wannaporn Ngernbumrung ◽  
Sukalaya Lerdlum
Keyword(s):  
Computed Tomography ◽  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Arterial Occlusion ◽  
Intravenous Thrombolysis ◽  
P Value ◽  
Anterior Circulation ◽  
Independent Predictive Factor ◽  
Middle Cerebral Artery Infarction ◽  
Clinical Criteria

Background: Cerebral collateral circulation is necessary to maintain cerebral blood flow and penumbra when arterial insufficiency occurred. Only a few studies about collateral status on development of malignant middle cerebral artery infarction (mMCAi) have been documented. Objective: To determine whether collateral status evaluated by single phase computed tomographic angiography (CTA) help prediction of mMCAi in patients with large arterial occlusion whom not received endovascular treatment. Material and Methods: We retrospectively reviewed patients with acute ischemic stroke in anterior circulation in our institute during January 2015 to December 2015. We analyzed clinical data, baseline National Institutes of Health Stroke Scale (NIHSS), Alberta Stroke Program Early CT Score (ASPECTS) on baseline nonenhanced computed tomography of the brain (NECT brain), and CTA collateral status. Malignant MCA infarction was defined according to clinical criteria. Results: Thirty-five patients were included. Mean age was 68.8±15.56 years. Mean baseline NIHSS and baseline ASPECTS were 17(±5) and 6(±3), respectively. All patients received intravenous thrombolysis. CTA collateral status and baseline NECT ASPECTS significantly correlated with development of mMCAi (P-value = 0.007 and 0.001). Only baseline NECT ASPECTS was an independent predictive factor for mMCAi (OR 0.63, 95%CI 0.46-0.86, P-value =0.004). Patients with baseline NECT ASPECTS ≤ 7 were more likely develop mMCAi (OR 14.29 95%CI 1.57-129.94, P-value 0.018). Conclusion: In acute stroke patients with proximal MCA or ICA occlusion received intravenous thrombolysis alone, baseline NECT ASPECTS and CTA collateral status were significantly correlate with development of mMCAi. However, only baseline ASPECTS ≤ 7 was an independent predictor for mMCAi.

scholarly journals Adiposity and Outcome After Ischemic Stroke

Stroke ◽  
2021 ◽  
Vol 52 (1) ◽  
pp. 144-151
Author(s):  
Zuolu Liu ◽  
Nerses Sanossian ◽  
Sidney Starkman ◽  
Gilda Avila-Rinek ◽  
Marc Eckstein ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Scale Score ◽  
Odds Ratio ◽  
Functional Outcomes ◽  
National Institutes Of Health ◽  
Modified Rankin Scale ◽  
Related Quality ◽  
Severely Obese

Background and Purpose: A survival advantage among individuals with higher body mass index (BMI) has been observed for diverse acute illnesses, including stroke, and termed the obesity paradox. However, prior ischemic stroke studies have generally tested only for linear rather than nonlinear relations between body mass and outcome, and few studies have investigated poststroke functional outcomes in addition to mortality. Methods: We analyzed consecutive patients with acute ischemic stroke enrolled in a 60-center acute treatment trial, the NIH FAST-MAG acute stroke trial. Outcomes at 3 months analyzed were (1) death; (2) disability or death (modified Rankin Scale score, 2–6); and (3) low stroke-related quality of life (Stroke Impact Scale<median). Relations with BMI were analyzed univariately and in multivariate models adjusting for 14 additional prognostic variables. Results: Among 1033 patients with acute ischemic stroke, average age was 71 years (±13), 45.1% female, National Institutes of Health Stroke Scale 10.6 (±8.3), and BMI 27.5 (±5.6). In both unadjusted and adjusted analysis, increasing BMI was linearly associated with improved 3-month survival ( P =0.01) odds ratios in adjusted analysis for mortality declined across the BMI categories of underweight (odds ratio, 1.7 [CI, 0.6–4.9]), normal (odds ratio, 1), overweight (0.9 [CI, 0.5–1.4]), obese (0.5, [CI, 0.3–1.0]), and severely obese (0.4 [CI, 0.2–0.9]). In unadjusted analysis, increasing BMI showed a U-shaped relation to poststroke disability or death (modified Rankin Scale score, 2–6), with odds ratios of modified Rankin Scale score, 2 to 6 for underweight, overweight, and obese declined initially when compared with normal weight patients, but then increased again in severely obese patients, suggesting a U-shaped or J-shaped relation. After adjustment, including for baseline National Institutes of Health Stroke Scale, modified Rankin Scale score 2 to 6 was no longer related to adiposity. Conclusions: Mortality and functional outcomes after acute ischemic stroke have disparate relations with patients’ adiposity. Higher BMI is linearly associated with increased survival; and BMI has a U-shaped or J-shaped relation to disability and stroke-related quality of life. Potential mechanisms including nutritional reserve aiding survival during recovery and greater frequency of atherosclerotic than thromboembolic infarcts in individuals with higher BMI.

Collateral Circulation in Thrombectomy for Stroke After 6 to 24 Hours in the DAWN Trial

Stroke ◽  
2021 ◽  
Author(s):  
David S. Liebeskind ◽  
Hamidreza Saber ◽  
Bin Xiang ◽  
Ashutosh P. Jadhav ◽  
Tudor G. Jovin ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Scale Score ◽  
Collateral Circulation ◽  
Time Window ◽  
Infarct Volume ◽  
Late Time ◽  
Collateral Flow ◽  
Modified Rankin Scale ◽  
Diverse Range ◽  
Wide Range

Background and Purpose: Collaterals govern the pace and severity of cerebral ischemia, distinguishing fast or slow progressors and corresponding therapeutic opportunities. The fate of sustained collateral perfusion or collateral failure is poorly characterized. We evaluated the nature and impact of collaterals on outcomes in the late time window DAWN trial (Diffusion-Weighted Imaging or Computed Tomography Perfusion Assessment With Clinical Mismatch in the Triage of Wake-Up and Late Presenting Strokes Undergoing Neurointervention With Trevo). Methods: The DAWN Imaging Core Lab prospectively scored collateral grade on baseline computed tomography angiography (CTA; endovascular and control arms) and digital subtraction angiography (DSA; endovascular arm only), blinded to all other data. CTA collaterals were graded with the Tan scale and DSA collaterals were scored by ASITN grade (American Society of Interventional and Therapeutic Neuroradiology collateral score). Descriptive statistics characterized CTA collateral grade in all DAWN subjects and DSA collaterals in the endovascular arm. The relationship between collateral grade and day 90 outcomes were separately analyzed for each treatment arm. Results: Collateral circulation to the ischemic territory was evaluated on CTA (n=144; median 2, 0–3) and DSA (n=57; median 2, 1–4) before thrombectomy in 161 DAWN subjects (mean age 69.8±13.6 years; 55.3% women; 91 endovascular therapy, 70 control). CTA revealed a broad range of collaterals (Tan grade 3, n=64 [44%]; 2, n=45 [31%]; 1, n=31 [22%]; 0, n=4 [3%]). DSA also showed a diverse range of collateral grades (ASITN grade 4, n=4; 3, n=22; 2, n=27; 1, n=4). Across treatment arms, baseline demographics, clinical variables except atrial fibrillation (41.6% endovascular versus 25.0% controls, P =0.04), and CTA collateral grades were balanced. Differences were seen across the 3 levels of collateral flow (good, fair, poor) for baseline National Institutes of Health Stroke Scale, blood glucose <150, diabetes, previous ischemic stroke, baseline and 24-hour core infarct volume, baseline and 24-hour Alberta Stroke Program Early CT Score, dramatic infarct progression, final Thrombolysis in Cerebral Infarction 2b+, and death. Collateral flow was a significant predictor of 90-day modified Rankin Scale score of 0 to 2 in the endovascular arm, with 43.7% (31/71) of subjects with good collaterals, 30.8% (16/52) of subjects with fair collaterals, and 17.7% (6/34) of subjects with poor collaterals reaching modified Rankin Scale score of 0 to 2 at 90 days ( P =0.026). Conclusions: DAWN subjects enrolled at 6 to 24 hours after onset with limited infarct cores had a wide range of collateral grades on both CTA and DSA. Even in this late time window, better collaterals lead to slower stroke progression and better functional outcomes. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02142283.

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