Combined Lysis of Thrombus with Ultrasound and Systemic Tissue Plasminogen Activator for Emergent Revascularization in Acute Ischemic Stroke (Clotbust-ER): Design and Methodology of a Multinational Phase 3 Trial

Background

We designed a Phase 3 clinical trial to determine the safety and efficacy of adding transcranial ultrasound using an operator-independent headframe to recombinant tissue-plasminogen-activator for the treatment of acute ischemic stroke.

Methods

Combined lysis of thrombus with ultrasound and systemic tissue-plasminogen-activator for emergent revascularization in acute ischemic stroke is a randomized, double-blind, placebo-controlled clinical trial that will enroll subjects with the following main inclusion criteria: less than 4·5 hours from symptom onset (three-hours in US and Canada), age 18–80 years, baseline National Institutes of Health Stroke Scale score ≥ 10, and premorbid modified-Rankin-score of 0–1, eligibility for full dose recombinant tissue-plasminogen-activator. Subjects will receive two-hours of 2-MHz pulsed wave transcranial ultrasound (target group) or sham ultrasound (control group). The projected sample size is approximately 824 subjects.

Results

The primary endpoint, based on intention-to-treat criteria of patients enrolled within three-hours of symptom onset is the comparison between target and control groups of modified-Rankin-score scores at day 90 poststroke assessed using the proportional odds method. The study will have two planned interim analyses after approximately one-third and two-thirds of subjects have reached the 90-day modified-Rankin-score evaluation. Safety outcomes are symptomatic intracranial hemorrhage within 24 h and an overall analysis of adverse events.

Conclusions

Since intravenous recombinant tissue-plasminogen-activator remains the only medical therapy to reverse ischemic stroke applicable in the emergency department, our trial will determine if the additional use of transcranial ultrasound improves functional outcomes in patients with severe acute ischemic stroke (NCT#01098981).

Thrombectomy within 8 hours after symptom onset in ischemic stroke

BACKGROUND

We aimed to assess the safety and efficacy of thrombectomy for the treatment of stroke in a trial embedded within a population-based stroke reperfusion registry.

METHODS

During a 2-year period at four centers in Catalonia, Spain, we randomly assigned 206 patients who could be treated within 8 hours after the onset of symptoms of acute ischemic stroke to receive either medical therapy (including intravenous alteplase when eligible) and endovascular therapy with the Solitaire stent retriever (thrombectomy group) or medical therapy alone (control group). All patients had confirmed proximal anterior circulation occlusion and the absence of a large infarct on neuroimaging. In all study patients, the use of alteplase either did not achieve revascularization or was contraindicated. The primary outcome was the severity of global disability at 90 days, as measured on the modified Rankin scale (ranging from 0 [no symptoms] to 6 [death]). Although the maximum planned sample size was 690, enrollment was halted early because of loss of equipoise after positive results for thrombectomy were reported from other similar trials.

RESULTS

Thrombectomy reduced the severity of disability over the range of the modified Rankin scale (adjusted odds ratio for improvement of 1 point, 1.7; 95% confidence interval [CI], 1.05 to 2.8) and led to higher rates of functional independence (a score of 0 to 2) at 90 days (43.7% vs. 28.2%; adjusted odds ratio, 2.1; 95% CI, 1.1 to 4.0). At 90 days, the rates of symptomatic intracranial hemorrhage were 1.9% in both the thrombectomy group and the control group (P=1.00), and rates of death were 18.4% and 15.5%, respectively (P=0.60). Registry data indicated that only eight patients who met the eligibility criteria were treated outside the trial at participating hospitals.

CONCLUSIONS

Among patients with anterior circulation stroke who could be treated within 8 hours after symptom onset, stent retriever thrombectomy reduced the severity of post-stroke disability and increased the rate of functional independence. (Funded by Fundació Ictus Malaltia Vascular through an unrestricted grant from Covidien and others; REVASCAT ClinicalTrials.gov number, NCT01692379.).

Effect Size Estimates for the ESCAPE Trial: Proportional Odds Regression Versus Other Statistical Methods

BACKGROUND AND PURPOSE

Ordinal outcomes, such as modified Rankin Scale (mRS), are the standard primary end points in acute stroke trials. Regression models for assessing treatment efficacy after adjusting for baseline covariates have been developed for continuous, binary, or ordinal end points. There has been no consensus on the best choice of method for analyzing these data.

METHODS

We compared several regression models for assessing treatment efficacy in acute stroke trials using existing data sets from the Interventional Management of Stroke-III and Prolyse in Acute Cerebral Thromboembolism II (PROACT-2) trials. Patients with baseline non-contrast computed tomographic Alberta Stroke Program Early CT Score (ASPECTS) > 5, baseline computed tomographic angiography, or conventional angiogram showing an intracranial internal carotid artery or middle cerebral artery trunk (M-1) occlusion, adequate collateral circulation shown on computed tomographic angiography, and treatment times of non-contrast computed tomographic to groin puncture of ≤90 minutes, were included. Monte Carlo techniques were used to compare the statistical power of these regression models under a variety of simulated data analytic scenarios.

RESULTS

Binary logistic regression showed greater power when the treatment is predicted to show evidence of benefit on one end of the mRS with no other gains across other levels of the scale. Proportional odds regression showed greater power when the treatment is predicted to show evidence of improvement on both ends of the mRS.

CONCLUSIONS

The mRS distribution for both treatment and control groups influences the power of the investigated statistical models to assess treatment efficacy. A careful evaluation of the expected outcome distribution across the mRS scale is required to determine the best choice of primary analysis.

Twelve-Month Clinical and Quality-of-Life Outcomes in the Interventional Management of Stroke III Trial

BACKGROUND AND PURPOSE

Randomized trials have indicated a benefit for endovascular therapy in appropriately selected stroke patients at 3 months, but data regarding outcomes at 12 months are currently lacking.

METHODS

We compared functional and quality-of-life outcomes at 12 months overall and by stroke severity in stroke patients treated with intravenous tissue-type plasminogen activator followed by endovascular treatment as compared with intravenous tissue-type plasminogen activator alone in the Interventional Management of Stroke III Trial. The key outcome measures were a modified Rankin Scale score ≤2 (functional independence) and the Euro-QoL EQ-5D, a health-related quality-of-life measure.

RESULTS

656 subjects with moderate-to-severe stroke (National Institutes of Health Stroke Scale ≥8) were enrolled at 58 centers in the United States (41 sites), Canada (7), Australia (4), and Europe (6). There was an interaction between treatment group and stroke severity in the repeated measures analysis of modified Rankin Scale ≤2 outcome (P=0.039). In the 204 participants with severe stroke (National Institutes of Health Stroke Scale ≥20), a greater proportion of the endovascular group had a modified Rankin Scale ≤2 (32.5%) at 12 months as compared with the intravenous tissue-type plasminogen activator group (18.6%, P=0.037); no difference was seen for the 452 participants with moderately severe strokes (55.6% versus 57.7%). In participants with severe stroke, the endovascular group had 35.2 (95% confidence interval: 2.1, 73.3) more quality-adjusted-days over 12 months as compared with intravenous tissue-type plasminogen activator alone.

CONCLUSIONS

Endovascular therapy improves functional outcome and health-related quality-of-life at 12 months after severe ischemic stroke.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00359424.

Rationale, Design, and Progress of the ENhanced Control of Hypertension ANd Thrombolysis Stroke Study (ENCHANTED) Trial: An International Multicenter 2 × 2 Quasi-Factorial Randomized Controlled Trial of Low- vs. Standard-Dose rt-PA and Early Intensive vs. Guideline-Recommended Blood Pressure Lowering in Patients with Acute Ischaemic Stroke Eligible for Thrombolysis Treatment

Rationale

Controversy exists over the optimal dose of intravenous (iv) recombinant tissue plasminogen activator (rt-PA) and degree of blood pressure (BP) control in acute ischaemic stroke (AIS). Asian studies suggest low-dose (0·6 mg/kg) is more efficacious than standard-dose (0·9 mg/kg) iv rt-PA, and guidelines recommend reducing systolic BP to <185 mmHg before and <180 mmHg after use of iv rt-PA, despite observational studies indicating better outcomes at much lower (<140 mmHg) systolic BP levels in this patient group.

Aims

The study aims to assess in thrombolysis-eligible AIS patients whether: (i) low-dose (0·6 mg/kg body weight; maximum 60 mg) iv rt-PA has non-inferior efficacy and lower risk of symptomatic intracerebral haemorrhage (sICH) compared to standard-dose (0·9 mg/kg body weight; maximum 90 mg) iv rt-PA; and (ii) early intensive BP lowering (systolic target 130–140 mmHg) has superior efficacy and lower risk of any ICH compared to guideline-recommended BP control (systolic target < 180 mmHg).

Design

The ENhanced Control of Hypertension And Thrombolysis strokE stuDy (ENCHANTED) trial is an independent, 2 × 2 quasi-factorial, active-comparison, prospective, randomized, open blinded endpoint (PROBE), clinical trial that is evaluating Arm [A] ‘rt-PA dose’ and/or Arm [B] ‘BP control’, using central Internet randomization and data collection in patients fulfilling local criteria for thrombolysis and clinician uncertainty over the study treatments. The treatment arms will be analyzed separately.

Study outcomes

The primary study outcome in both trial Arms is death or disability according to the modified Rankin scale (mRS, scores 2–6) assessed at 90 days. Secondary outcomes include sICH, any ICH, a shift (‘improvement’) in function across mRS scores, separately on death and disability, early neurological deterioration, recurrent major vascular events, health-related quality of life, length of hospital stay, need for permanent residential care, and health care costs.

Results

Following launch of the trial in February 2012, the study has recruited more than 2500 patients across a global network of approximately 100 sites in 15 countries. The required sample sizes are 3300 for Arm [A] and 2300 for Arm [B], which will provide >90% power to detect non-inferiority of low-dose iv rt-PA and superiority of intensive BP lowering on the primary clinical outcome, respectively.

Conclusions

Low-dose iv rt-PA and early intensive BP lowering could provide more affordable and safer use of thrombolysis treatment for patients with AIS worldwide.

Differential Effect of Baseline Computed Tomographic Angiography Collaterals on Clinical Outcome in Patients Enrolled in the Interventional Management of Stroke III Trial

BACKGROUND AND PURPOSE

In the Interventional Management of Stroke (IMS) III trial, we sought to demonstrate evidence of a differential treatment effect of endovascular treatment of acute ischemic stroke compared with intravenous tissue-type plasminogen activator, according to baseline collateral status measured using computed tomographic angiography.

METHODS

Of 656 patients enrolled in Interventional Management of Stroke III trial, 306 had baseline computed tomographic angiography. Of these, 185 patients had M1 middle cerebral artery ± intracranial internal carotid artery occlusion, where baseline collateral status could be measured. Collateral status was assessed by consensus using 3 different ordinal scales and categorized as good, intermediate, and poor. Multivariable modeling was used to assess the effect of collateral status and treatment type on clinical outcome by modified Rankin Scale (mRS 0-2, mRS 0-1, and the ordinal mRS).

RESULTS

Of 185 patients, 126 randomized to endovascular therapy (87.6% recanalized, 41.3% 90-day mRS 0-2) and 59 to intravenous tissue-type plasminogen activator only (60.5% recanalized, 30.5% 90-day mRS 0-2). In multivariable modeling, collateral status was a significant predictor of all clinical outcomes (P<0.05). Maximal benefit with endovascular treatment across all clinical outcomes was seen in patients with intermediate collaterals, some benefit in patients with good collaterals, and none in patients with poor collaterals, although small sample size limited the power of the analysis to show a statistically significant interaction between collateral status and treatment type (P>0.05).

CONCLUSION

Using data from a large randomized controlled trial (IMS III), we show that baseline computed tomographic angiography collaterals are a robust determinant of final clinical outcome and could be used to select patients for endovascular therapy.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov/ct2/show/. Unique identifier: 0020NCT00359424.

Randomized assessment of rapid endovascular treatment of ischemic stroke

BACKGROUND

Among patients with a proximal vessel occlusion in the anterior circulation, 60 to 80% of patients die within 90 days after stroke onset or do not regain functional independence despite alteplase treatment. We evaluated rapid endovascular treatment in addition to standard care in patients with acute ischemic stroke with a small infarct core, a proximal intracranial arterial occlusion, and moderate-to-good collateral circulation.

METHODS

We randomly assigned participants to receive standard care (control group) or standard care plus endovascular treatment with the use of available thrombectomy devices (intervention group). Patients with a proximal intracranial occlusion in the anterior circulation were included up to 12 hours after symptom onset. Patients with a large infarct core or poor collateral circulation on computed tomography (CT) and CT angiography were excluded. Workflow times were measured against predetermined targets. The primary outcome was the score on the modified Rankin scale (range, 0 [no symptoms] to 6 [death]) at 90 days. A proportional odds model was used to calculate the common odds ratio as a measure of the likelihood that the intervention would lead to lower scores on the modified Rankin scale than would control care (shift analysis).

RESULTS

The trial was stopped early because of efficacy. At 22 centers worldwide, 316 participants were enrolled, of whom 238 received intravenous alteplase (120 in the intervention group and 118 in the control group). In the intervention group, the median time from study CT of the head to first reperfusion was 84 minutes. The rate of functional independence (90-day modified Rankin score of 0 to 2) was increased with the intervention (53.0%, vs. 29.3% in the control group; P<0.001). The primary outcome favored the intervention (common odds ratio, 2.6; 95% confidence interval, 1.7 to 3.8; P<0.001), and the intervention was associated with reduced mortality (10.4%, vs. 19.0% in the control group; P=0.04). Symptomatic intracerebral hemorrhage occurred in 3.6% of participants in intervention group and 2.7% of participants in control group (P=0.75).

CONCLUSIONS

Among patients with acute ischemic stroke with a proximal vessel occlusion, a small infarct core, and moderate-to-good collateral circulation, rapid endovascular treatment improved functional outcomes and reduced mortality. (Funded by Covidien and others; ESCAPE ClinicalTrials.gov number, NCT01778335.).

Risk stratification and stroke prevention therapy care gaps in Canadian atrial fibrillation patients (from the Co-ordinated National Network to Engage Physicians in the Care and Treatment of Patients With Atrial Fibrillation chart audit)

The objectives of this national chart audit (January to June 2013) of 6,346 patients with atrial fibrillation (AF; ≥18 years without a significant heart valve disorder) from 647 primary care physicians were to (1) describe the frequency of stroke and bleed risk assessments in patients with nonvalvular AF by primary care physicians, including the accuracy of these assessments relative to established predictive indexes; (2) outline contemporary methods of anticoagulation used; and (3) report the time in the therapeutic range among patients prescribed warfarin. An annual stroke risk assessment was not undertaken in 15% and estimated without a formal risk tool in 33%; agreement with CHADS2 score estimation was seen in 87% of patients. Major bleeding risk assessment was not undertaken in 25% and estimated without a formal risk tool in 47%; agreement with HAS-BLED score estimation was observed in 64% with physician overestimation in 26% of patients. Antithrombotic therapy included warfarin (58%), dabigatran (22%), rivaroxaban (14%), and apixaban (<1%). Among warfarin-treated patients, the median international normalized ratio was 2.4 and time in therapeutic range (TTR) was 73%; however, the TTR was <50% in 845 (25%), 50% to 69% in 674 (20%), and ≥70% in 1,827 (55%) patients. In conclusion, we describe a contemporary real-world elderly population with AF at important risk for stroke. There is apparent overestimation of bleeding risk in many patients. Warfarin was the dominant stroke prevention treatment; however, the suggested TTR target was achieved in only 55% of these patients.

Tenecteplase-tissue-type plasminogen activator evaluation for minor ischemic stroke with proven occlusion

BACKGROUND AND PURPOSE

Minor stroke and transient ischemic attack with an intracranial occlusion are associated with neurological deterioration and disability. Tenecteplase (TNK-tissue-type plasminogen activator) compared with alteplase is easier to administer, has a longer half-life, higher fibrin specificity, possibly a lower rate of intracranial hemorrhage, and may be an ideal thrombolytic agent in this population.

METHODS

TNK-Tissue-Type Plasminogen Activator Evaluation for Minor Ischemic Stroke With Proven Occlusion (TEMPO-1) was a multicenter, prospective, uncontrolled, TNK-tissue-type plasminogen activator dose-escalation, safety, and feasibility trial. Patients with a National Institutes of Health Stroke Scale ≤5 within 12 hours of symptom onset, intracranial arterial occlusion on computed tomographic angiography and absence of well-evolved infarction were eligible. Fifty patients were enrolled; 25 patients at a dose of 0.1 mg/kg, and 25 patients at 0.25 mg/kg. Primary outcome was the rate of drug-related serious adverse events. Secondary outcomes included recanalization and 90-day neurological outcome (modified Rankin Scale, 0-1).

RESULTS

Median baseline National Institutes of Health Stroke Scale was 2.5 (interquartile range, 1), and median age was 71 (interquartile range, 22) years. There were no drug-related serious adverse events in tier 1. In tier 2, there was 1 symptomatic intracranial hemorrhage (4%; 95% confidence interval, 0.01-20.0). Stroke progression occurred in 6% of cases. Overall, 66% had excellent functional outcome (modified Rankin Scale, 0-1) at 90 days. Recanalization rates were high; 0.1 mg/kg (39% complete and 17% partial), 0.25 mg/kg (52% complete and 9% partial). Complete recanalization was significantly related to excellent functional outcome (modified Rankin Scale, 0-1) at 90 days (relative risk, 1.65; 95% confidence interval, 1.09-2.5; P=0.026).

CONCLUSIONS

Administration of TNK-tissue-type plasminogen activator in minor stroke with intracranial occlusion is both feasible and safe. A larger randomized controlled trial is needed to prove that this treatment is efficacious.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT01654445.

Abstract W P12: Baseline Predictors of the Malignant Collateral Profile in IMS III

Background: Collateral circulation has repeatedly been cited as a decisive factor in successful angiographic and clinical outcomes after endovascular therapy, offering rational selection criteria. Identifying patients with a malignant collateral profile, portending poor outcome, would greatly enhance decision-making in acute stroke. We analyzed the IMS III dataset to delineate baseline predictors of poor angiographic collaterals.

Methods: Collateral grade was prospectively evaluated by the angiography core lab in IMS III. Poor collaterals or a malignant collateral profile was defined as ASITN grade 0-1.

Baseline clinical, laboratory and non-contrast CT variables were evaluated in univariate and multivariable logistic regression as predictors of the malignant collateral profile.

Results: 278 patients (mean age 65.3±12.6 years, 54% women, median NIHSS 17 (IQR 13-20) had collateral grading assessed at angiography. Malignant collaterals (ASITN 0-1) were noted in 77/278 (28%). Univariate analyses revealed that only history of HTN (88.3 vs. 71.0%, p=0.004), CHF (17.6 vs.8.0%, p=0.040), admission DBP (89±24 vs. 81±17 (mm Hg, mean±SD), p=0.002), NIHSS>19 (40.3 vs. 28.4%, p=0.080), distal arterial occlusion location (p=0.002) and ASPECTS 0-4 (24.7 vs. 9.4%, p=0.002) were associated with malignant collaterals. Time from stroke onset to angiography was unrelated to collateral grade. Predictors in multivariable analyses included ASPECTS 0-4 (OR 3.72, 95%CI (1.60-8.66), p=0.002), HTN (OR 2.33, 95%CI (1.01-5.38), p=0.047), NIHSS>19 (OR 2.26, 95%CI (1.16-4.40), p=0.017), distal arterial occlusion (OR 2.08, 95%CI (1.43-3.04), p<0.001) and higher admission DBP (OR 1.02 per mm Hg, 95%CI (1.00-1.03), p=0.035). When ASPECTS 5-10, only NIHSS>19 (OR 2.81, 95%CI (1.35-5.86), p=0.006) and distal arterial occlusion (OR 2.58, 95%CI (1.70-3.92), p<0.001) predicted malignant collaterals.

Conclusions: Elevated diastolic blood pressure, history of hypertension, NIHSS>19, lower ASPECTS and distal arterial occlusion are strong predictors of the malignant collateral profile. Future studies should validate and implement a concomitant risk score for triage of acute stroke patients.

Abstract W P56: Using The M2 Vessel Diameter And Baseline NIHSS To Identify Which M2 Occlusions Should Be Treated Endovascularly?

Introduction: IV tPA is the primary acute treatment for M2 occlusions yet outcomes and recanalization rates are less than optimal. Endovascular treatment may be a more suitable treatment option in some but not all M2 occlusions yet are excluded from most current endovascular trials. Current methodologies to characterize M2s are complex and quite subjective. A simple and practical approach to evaluating M2s quickly for endovascular treatment is needed. We measured M2 cross-sectional diameter to determine if this method predicted 24-hour infarct volumes.

Methods: Patients from the ongoing prospective multicenter INTERRSECT recanalization study with an M2 occlusion identified by baseline CTA were included. Two readers measured M2 diameter on baseline CTA at the most distal point of normal vessel upstream to the clot by consensus. Recanalization (modified AOL score 2-3) was assessed on 4 hour follow-up CTA. Infarct volume was measured on 24 hr CT/MRI.

Results: 103 patients (mean age 74.1 yrs, SD=12.7; 46.5% male; median baseline NIHSS 8, IQR=7) had M2 occlusion on baseline CTA. 76/103 received IV t-PA. Recanalization was noted in 46/92 (50%) patients. Median 24-hr infarct volume was 4.28 ml (IQR=22.67 ml). In multivariable linear regression, M2 diameter (p<0.01) and baseline NIHSS (p=0.01) were associated with final infarct volume but not recanalization (p=53). Median final infarct volume was 41.6 ml (IQR=50.4) in patients with M2 diameter>2mm and baseline NIHSS>5 vs < 10 ml in all the other 3 groups (p<0.01; equality of medians test; see figure).

Conclusion: Patients with M2 diameter > 2 mm just proximal to the occlusion and baseline NIHSS > 5 have much higher final infarct volumes suggesting a role for ultra-early recanalization that is offered by endovascular treatment. Such patients could be selected for endovascular therapy in future trials or clinical practice.

Abstract T P5: Sequential and Post-procedure ASPECTS Predict Clinical Outcome in Mechanical Thrombectomy of Acute Anterior Circulation Ischemic Stroke

Purpose: Final ASPECTS has been shown to predict patient outcomes after endovascular therapy in stroke. The goal of this study was to compare sequential ASPECTS imaging pre-treatment and post-treatment in predicting outcome.

Methods: The PICS Study is a prospective registry of clinical and imaging data in proximal artery occlusion patients treated with the Penumbra System. In multivariate analysis, variables assessed for relationship to 90 day mRS included age, gender, time to reperfusion, occlusion location, ASPECTS, and NIHSS. ASPECTS scores were assessed by a central core laboratory, blinded except for stroke side.

Results: In this study, 141 patients with mean age 67.9 ± 15.6 and median admission NIHSS score 16.0 (IQR 12.0-21.0) met study criteria. Univariate predictors of 90 day mRS included age, baseline NIHSS, 7 day/discharge NIHSS as well as post-treatment ASPECTS. After adjusting for age and baseline NIHSS, post procedure ASPECTS showed a stronger relationship with good outcome (p<0.0001) than pre-treatment ASPECTS (p=0.0520). Change in ASPECTS was also a significant predictor of 90 day mRS (p=0.0046) in the multivariate analysis.

Conclusion: Sequential and post procedure ASPECTS are better predictors of clinical outcome following endovascular therapy than pre-ASPECTS. Final infarct volume quantified using ASPECTS serves as a surrogate biomarker for long-term functional outcome.

Abstract T MP109: Leptomeningeal Collaterals, Ageing and Metabolic Syndrome in Development of White Matter Hyperintensities

Background: Ageing and metabolic syndrome are associated with poor leptomeningeal collateral status. Animal studies suggest that collateral rarefaction and consequent decrease in vascular efficiency may result in increase in white matter hyperintensities. Using mediational analysis, we test if the known effect of ageing and metabolic syndrome on development of white matter hyperintensities is mediated through collateral status.

Methods: Data are from the Keimyung Stroke Registry. Consecutive patients with M1 segment middle cerebral artery (MCA) ± intracranial internal carotid artery (ICA) occlusions on baseline CT-angiography (CTA) and brain MRI done within 90 minutes after admission CT/CTA, from May 2004 to July 2009, were included. Baseline and follow-up imaging was analyzed blinded to all clinical information. Two raters assessed leptomeningeal collaterals on baseline CTA by consensus, using previously validated regional leptomeningeal score (rLMC). FLAIR volume of white matter hyperintensities (ml) was measured in the unaffected hemisphere using Quantomo® software. The template of Baron and Kenney along with two tests (Sobel’s and Aroian’s) was used to test for the presence of mediation.

Results: Baseline characteristics (n=120): mean age 67.4±11.4 years, male (53.3%), median baseline NIHSS 14 (IQR 11-20), and median stroke symptom onset to CTA 166 minutes (IQR 96-262). Poor collateral status at baseline (rLMC score 0-10) was seen in 42/120 (35%). Mean periventricular hyperintensity (PVH) volume was 6.5 ml (SD=6.0) while mean white matter hyperintensity (WMH-total) volume was 8.6 ml (SD=8.0). Higher age was associated with increased PVH and WMH-total (p<0.01) while metabolic syndrome was associated with increased PVH only (p=0.03). We did not find statistical evidence of leptomeningeal collaterals mediating the association between ageing and PVH/WMH-total or between metabolic syndrome and PVH (Sobel’s and Aroian’s test p>0.05).

Conclusion: The effect of ageing and metabolic syndrome on development of white matter hyperintensities is independent of an effect mediated through the poor collateral status.

Abstract 93: Do Intracerebral Hemorrhage “Non-Expanders” Actually Expand into the Ventricular Space?

Background: The CT-angiography spot sign as a predictor of hematoma expansion (HE) is limited by its modest sensitivity and PPV. Spot sign studies restrict HE definitions to the parenchymal component of ICH and do not consistently evaluate intraventricular hemorrhage (IVH) expansion. Decompression of ICH into the ventricular space can lead to underestimation of HE and overestimation of false-positive spot signs. We hypothesized that a proportion of ICH “non-expanders” expand into the ventricular space and including IVH expansion in HE definitions will improve the predictive performance of the spot sign. Our objectives were: 1) determine the proportion of ICH “non-expanders” who have IVH expansion, 2) determine the proportion of “false-positive” spot signs that have IVH expansion, 3) compare the known predictive performance of the spot sign to its performance when using an HE definition incorporating IVH expansion, and 4) explore the predictors of IVH expansion.

Methods: We analyzed patients from the multicenter PREDICT ICH spot sign study. We defined HE as ≥6mL or ≥33% ICH expansion or >2ml IVH expansion, and compared the performance of this new definition with the conventional 6mL/33% parenchymal definition using ROC analysis. We used regression analysis to determine the predictors of IVH expansion.

Results: Of 315 patients with complete imaging, 215 did not meet the 6mL/33% expansion definition ("non-expanders"). Only 14/215 (6.5%) of “non-expanders” had ≥2mL IVH expansion. Of the “false positive” spot signs, 4/39 (10.3%) had >2mL ventricular expansion. The AUC for spot sign to predict significant ICH expansion was 0.65 [95% CI 0.58-0.72], which was no different then when IVH expansion was added to the HE definition: AUC 0.64 [95% CI 0.58-0.71]. Predictors for IVH expansion included IVH at baseline (aOR 2.5, p=0.013), elevated INR (aOR 2.5, p=0.011), and spot sign (aOR 5.9, p<0.001).

Conclusions: IVH expansion occurs in a small minority of “non-expanders”, and only 10% of “false positive” post signs actually expended in the ventricular space. Furthermore, revising HE definitions to include IVH expansion did not alter the predictive performance of the spot sign.

Abstract T P21: Complex Internal Carotid Artery T Occlusion By Computed Tomographic Angiography Is A Very Malignant Subtype With Massive Infarcts And Poor Outcomes Despite Revascularization Treatment

Background: ICA T/L occlusions appear to have a particular poor prognosis due to low recanalization with intravenous tissue plasminogen activator alone. What is not known however is whether all ICA T/L occlusions remain as good candidates for endovascular treatment. We divided ICA T/L occlusions into distinct types according to Willisian collaterals and compared infarct core volumes and clinical outcomes in the two groups as well as other anterior circulation occlusion sites.

Methods: We enrolled patients with acute ischemic stroke in anterior circulation whose CT angiography showed major intracranial artery occlusion. Patients were included if their MRI was taken just after CT scan and within 6 hours from onset. We classified patients into Complex ICA T, Simple ICA T/L, MCA M1, MCA M2, and extracranial to intracranial tandem groups. Among patients with ICA T/L occlusion, patients were classified into simple ICA T/L occlusion group if ACA A2 and PCA P2 segments are patent whereas those into complex ICA T group if A2, P2 or their distal branches were occluded, or contralateral occlusion was seen in ICA or contralesional A1 absent or hypoplastic. Other occlusion types were excluded in this study.

Results: Table shows comparisons among groups. Age, sex and vascular risk factors did not differ among groups. Initial NIHSS score was different among groups. Pretreatment infarct core volume with ADC value threshold of 600 x 10-5 mm2/s was significantly different according to cerebral artery occlusion types. Clinical outcome significantly differed among groups regarding NIHSS score at discharge, frequency of good outcome (mRS 0-2 at 3 months), and frequency of 3-month mortality.

Conclusion: We describe a subtype of carotid occlusions we have named as complex ICA T occlusions in which Willisian collateral flow is limited. This group is associated with very large infarct core volumes and poor 3-month outcomes despite acute revascularization treatment.

d’Esterre C, Qazi EM, Goyal M, Demchuk AM, Lee TY, Menon BK. Abstract W P27: Quantitative Measurement Of Blood Flow Around Intravascular Thrombus Using CT Perfusion T0 Maps

Introduction: Anterograde blood flow around thrombus and extent of retrograde collateral filling can affect thrombus lysis with IV tPA. Current assessment of blood flow around thrombus is however very subjective. The aim of the present study is to validate a newly devised method to quantify blood flow around thrombus using CT perfusion (CTP) T0 maps.

Methods: From the Prove-IT stroke-imaging database, perfusion CT and DSA images of stroke patients treated with IV tPA and/or IA thrombolysis were analyzed. We generated maps that measure delay in arrival time of contrast within the intracranial arterial tree (T0 maps) from that of the chosen arterial input function. A “positive sloped” regression line of T0 values from distal clot interface to at least 14 pixels (median 68 pixels) along the artery profile indicated presence of occult anterograde flow. Anterograde flow thus measured using the T0 maps was compared with anterograde flow assessed on first angiography of subsequent IA procedure.

Results: Of 37 patients (mean age 66 ± 13.5 years, 20 female), 35 (94.6%) were treated with IV tPA before DSA. Median time from CTP to first run angiography was 83 mins (IQR 53-100 mins). Positive slope were noted in 10 patients. Patients who had anterograde flow on first angiography were 10. Compared with anterograde flow on first run angio, positive slope on T0 map had a sensitivity of 80%, specificity of 92.6% and a positive predictive value of 80% and negative predictive value of 92.6%. In patients with anterograde flow on first angiography, median T0 time at proximal clot interface was 0.1 seconds (IQR 0-0.1) and at distal clot interface was 0.7 seconds (IQR 0.5-3.1). In patients without any anterograde flow on first angio, median T0 time at proximal clot interface was 0.1 seconds (IQR 0-0.3) while that at distal clot interface was 3.7 seconds (IQR 2.1-5.6).

Conclusions: The slope method on CTP T0 maps and measurement of T0 values around clot reliably measure presence of anterograde blood flow through thrombus.

Abstract T P12: Intraarterial (IA) Iodinated Radiographic Contrast Media (IRCM) Effect in the Interventional Management of Stroke (IMS) III Trial

Background: IRCM have variable anti-thrombotic, fibrinolytic, cytotoxic, hydrostatic, and vasoactive effects. IA low-osmolar iohexol (~700 mOsm/L) was associated with increased ICH in a rat MCA occlusion model compared to saline infusion. IA isosmolar iodixanol (280 mOsm/L) was associated with smaller infarcts and less ICH versus low-osmolar iopamidol and saline. Reduced odds of favorable outcome in patients receiving IV IRCM prior to IV rtPA has been suggested. No human stroke study has compared outcomes according to IA IRCM use.

Methods: 133 IMS III subjects underwent endovascular therapy (EVT) for M1 occlusion. mTICI 2B-3 reperfusion, 90-day mRS 0-2, asymptomatic ICH, symptomatic ICH, and 90-day mortality were analyzed according to use of either iso-osmolar iodixanol (n=31) or low-osmolar IRCM (n=102). Separate adjusted models were fit for each outcome. Variables imbalanced between IRCM types or associated with outcome (p<0.1) were considered potential covariates for adjusted models, including antiplatelet medication (67.7% iodixanol vs. 44.1%, p=0.021), coronary artery disease history (35.5% iodixanol vs. 19.6%, p=0.067) and age (iodixanol median 73 vs. 68.5 yrs, p=0.070). Adjusted relative risks were estimated using a log-link regression model following stepwise selection of covariates.

Results: % Differences for all specified outcomes in favor of the iodixanol group were identified. None of 11 baseline or EVT variables linked to outcome was in favor of the iodixanol group (p < 0.3). Unadjusted and adjusted relative risk point estimates were in favor of the iodixanol group for all specified outcomes (Table).

Conclusion: While there were no significant differences, relative risk point estimates for relevant specified endpoints for M1 occlusion are in favor of iodixanol use. Small sample size limits ability to show significant differences. Data remains hypothesis-generating. Potential mechanisms warrant further investigation.

Abstract 202: 2B or Not to Be? Defining Successful Reperfusion In IMS III

Background: The modified and original variants of the TICI scale (mTICI and oTICI) define substantial reperfusion in endovascular stroke therapy (EVT) as ≥50% (mTICI) or ≥67% (oTICI) of the downstream territory. Despite recent adoption of the mTICI definition, it remains uncertain which threshold better predicts good clinical outcome after EVT.

Methods: The angiography core lab of the IMS III trial evaluated use of the oTICI definition compared to the mTICI technical endpoint. Inclusion criteria were presence of an intracranial ICA or MCA M1 occlusion, active EVT and available 90-day mRS. Two expert readers independently reviewed the complete angiography studies to categorize mTICI 2B results into 50-66% vs. 67-99% reperfusion and differences were resolved by consensus. ROC analysis was performed to determine the optimal threshold for predicting good clinical outcome (mRS 0-2). Safety endpoints were mortality and symptomatic intracranial hemorrhage. Inter-rater agreement was assessed using the kappa statistic.

Results: 187 patients met inclusion criteria with mean age 65.7 years and median NIHSS 19 were included, with 56 ICA and 131 M1 occlusions. The mTICI was 0 in 32 patients, 1 in 17, 2A in 69, 2B in 64, and 3 in only 5. Of the 64 mTICI 2B cases, 38 (59%) were adjudicated as oTICI 2B (i.e., 67-99%). There was an increase in good outcomes with greater reperfusion (mTICI 2B, 46%; oTICI 2B, 53%; p<0.0001), although there was no significant pairwise difference between 50-66% vs. 67-99% (p=0.80). For good outcome, the c-statistic was non-significantly higher for mTICI vs. oTICI (0.76 vs. 0.73, p=0.19). Overall, the optimal threshold for predicting good outcome was mTICI 2B-3 (sensitivity 68%, specificity 75% vs. sensitivity 45%, specificity 86% for oTICI 2B-3). Similarly, mTICI 2B-3 was the optimal threshold for predicting decreased mortality and decreased sICH. Inter-rater agreement for discriminating 50-66% vs. 67-99% reperfusion was excellent (kappa=0.84).

Conclusions: Greater degrees of reperfusion are associated with a higher likelihood of good outcomes. The most effective threshold, however, for predicting both good clinical outcome and improved safety is mTICI 2B rather than oTICI 2B.

Abstract T P53: Regional Vascular Status On Multi-phase CTA Correlates Well With Regional CT Perfusion Estimates And Final Tissue Fate

Introduction: Multi-phase CTA (mCTA) is a new imaging tool that generates time resolved images of contrast filling-in and washout within pial vessels in ischemic brain regions. In this study, we seek to demonstrate criterion and predictive validity of this imaging tool regionally by comparing vascular status as assessed using mCTA with CT perfusion estimates and with final tissue fate.

Methods: Data is from PRove-IT, an ongoing multi-national prospective study that seeks to understand the utility of multi-modal imaging in the triage of acute ischemic stroke patients. Only patients with M1-MCA occlusions were included for the analysis. “Delay” in maximal pial vessel enhancement, “Extent” of maximal pial vessel enhancement and degree of “Washout” of contrast within these pial vessels was each graded on a 3-point scale in each of the 5 ASPECTS regions (M2-6)(Fig 1). CBF, CBV, MTT, T Max and T0 values were calculated within these same ASPECTS regions on CTP. Reperfusion status was assessed regionally using the Kim’s template. Final tissue fate per region was determined on 24 hr MR/CT.

Results: We included 45 patients (225 ASPECTS regions) in the study. Specific parameters on mCTA correlated with specific perfusion estimates on CTP [Delay and T0 time (Kruskal-Wallis p=0.001), Washout and MTT (p<0.001), Extent and CBV (p<0.001)] regionally. On multivariable linear regression, Washout (p=0.04) and Extent grade (p<0.001) in each region were independently associated with ipsi-regional CBF. Classification and regression tree analysis (CART) discriminated between regional CBF thresholds ranging from <7ml/100gm/min to >15ml/100gm/min using a combined “Washout+Extent” grade on mCTA. In the early reperfusers, this combined “Washout+Extent” grade was related significantly with tissue fate regionally (Fisher’s p=0.04).

Conclusion: Regional vascular status on mCTA provides similar information to CTP estimates and is capable of predicting final tissue fate regionally.

Abstract T P11: What Clinical Factors Predict An Intracranial Arterial Stenosis Responsible For An Intracranial Larger Artery Occlusion Treated By Endovascular Therapy?

Objectives: In Asian countries where intracranial arterial stenosis (ICAS) is a common etiology regarding large artery intracranial occlusions in stroke. We sought to identify any clinical, laboratory and baseline imaging variables that may predict ICAS prior to endovascular treatment compared with angiographically-defined embolism (ADE).

Methods: Patients were included if they had large cerebral artery occlusion in stroke on CT angiography and undertook transfemoral cerebral angiography, and if their onset to puncture time was within 8 hours. We defined ICAS and ADE by transfemoral cerebral angiography. ICAS was defined as fixed significant (> 50%) focal stenosis in the occlusion site, which could be seen in the final angiography or during the procedure of endovascular treatment. ADE was defined by no focal stenosis was evident after some recanalization achieved. Patients were excluded if their cause of stroke was associated or combined with other etiologies.

Results: Finally, a total of 157 patients were included for this study. Table shows comparisons of clinical laboratory and imaging characteristics between ICAS and ADE groups. Patients in ICAS group were younger and male-predominant than in those in ADE group. Dyslipidemia and smokers were more frequent in ICAS group. Total cholesterol level was higher in ICAS group than in ADE group. Compared to ADE an ICAS was much more common in the posterior circulation 11/30 versus only 12/127 in the anterior circulation (p<0.001). Independent predictors of ICAS on multivariable analysis were male gender (odds ratio 6.34 [95% CI, 1.23-32.85], p=0.028), posterior circulation involvement (5.37 [1.62-17.82], p=0.006) and total cholesterol level (1.02 [1.004-1.033], p=0.012).

Conclusion: The neurointerventionalist should prepare for the possibility of ICAS when performing endovascular treatment especially with posterior circulation occlusions in a Korean population.

Multiphase CT Angiography: A New Tool for the Imaging Triage of Patients with Acute Ischemic Stroke

PURPOSE

To describe the use of an imaging selection tool, multiphase computed tomographic (CT) angiography, in patients with acute ischemic stroke (AIS) and to demonstrate its interrater reliability and ability to help determine clinical outcome.

MATERIALS AND METHODS

The local ethics board approved this study. Data are from the pilot phase of PRoveIT, a prospective observational study analyzing utility of multimodal imaging in the triage of patients with AIS. Patients underwent baseline unenhanced CT, single-phase CT angiography of the head and neck, multiphase CT angiography, and perfusion CT. Multiphase CT angiography generates time-resolved images of pial arteries. Pial arterial filling was scored on a six-point ordinal scale, and interrater reliability was tested. Clinical outcomes included a 50% or greater decrease in National Institutes of Health Stroke Scale (NIHSS) over 24 hours and 90-day modified Rankin Scale (mRS) score of 0-2. The ability to predict clinical outcomes was compared between single-phase CT angiography, multiphase CT angiography, and perfusion CT by using receiver operating curve analysis, Akaike information criterion (AIC), and Bayesian information criterion (BIC).

RESULTS

A total of 147 patients were included. Interrater reliability for multiphase CT angiography is excellent (n = 30, κ = 0.81, P < .001). At receiver operating characteristic curve analysis, the ability to predict clinical outcome is modest (C statistic = 0.56, 95% confidence interval [CI]: 0.52, 0.63 for ≥50% decrease in NIHSS over 24 hours; C statistic = 0.6, 95% CI: 0.53, 0.68 for 90-day mRS score of 0-2) but better than that of models using single-phase CT angiography and perfusion CT (P < .05 overall). With AIC and BIC, models that use multiphase CT angiography are better than models that use single-phase CT angiography and perfusion CT for a decrease of 50% or more in NIHSS over 24 hours (AIC = 166, BIC = 171.7; values were lowest for multiphase CT angiography) and a 90-day mRS score of 0-2 (AIC = 132.1, BIC = 137.4; values were lowest for multiphase CT angiography).

CONCLUSION

Multiphase CT angiography is a reliable tool for imaging selection in patients with AIS.