MRI T2-Hyperintense Signal Structures in the Cervical Spinal Cord: Anterior Median Fissure versus Central Canal in Chiari and Control-An Exploratory Pilot Analysis

BACKGROUND AND PURPOSE

Cervical spine axial MRI T2-hyperintense fluid signal of the anterior median fissure and round hyperintense foci resembling either the central canal or base of the anterior median fissure are associated with a craniocaudad sagittal line, also simulating the central canal. On the basis of empiric observation, we hypothesized that hyperintense foci, the anterior median fissure, and the sagittal line are seen more frequently in patients with Chiari malformation type I, and the sagittal line may be the base of the anterior median fissure in some patients.

MATERIALS AND METHODS

Saggital line incidence and the incidence/frequency of hyperintense foci and anterior median fissure in 25 patients with Chiari I malformation and 25 contemporaneous age-matched controls were recorded in this prospective exploratory study as either combined (hyperintense foci+anterior median fissure in the same patient), connected (anterior median fissure extending to and appearing to be connected with hyperintense foci), or alone as hyperintense foci or an anterior median fissure. Hyperintense foci and anterior median fissure/patient, hyperintense foci/anterior median fissure ratios, and anterior median fissure extending to and appearing to be connected with hyperintense foci were compared in all, in hyperintense foci+anterior median fissure in the same patient, and in anterior median fissure extending to and appearing to be connected with hyperintense foci in patients with Chiari I malformation and controls.

RESULTS

Increased sagittal line incidence (56%), hyperintense foci (8.5/patient), and anterior median fissure (4.0/patient) frequency were identified in patients with Chiari I malformation versus controls (28%, 3.9/patient, and 2.7/patient, respectively). Increased anterior median fissure/patient, decreasing hyperintense foci/anterior median fissure ratio, and increasing anterior median fissure extending to and appearing to be connected with hyperintense foci/patient were identified in Chiari subgroups. A 21%-58% increase in observed anterior median fissure extending to and appearing connected to hyperintense foci in the entire cohort and multiple sagittal line subgroups compared with predicted occurred.

CONCLUSIONS

In addition to the anticipated increased incidence/frequency of sagittal line and hyperintense foci in patients with Chiari I malformation, an increased incidence and frequency of anterior median fissure and anterior median fissure extending to and appearing to be connected with hyperintense foci/patient were identified. We believe an anterior median fissure may contribute to a saggital line appearance in some patients with Chiari I malformation. While thin saggital line channels are usually ascribed to the central canal, we believe some may be due to the base of the anterior median fissure, created by pulsatile CSF hydrodynamics.

Abstract 79: Chronic and Acute Hypertension in Ischemic Stroke Are Distinct Markers of Impaired Collateral Circulation

Background: Acute blood pressure (BP) elevation in acute ischemic stroke (AIS) is common, yet the link with collateral circulation remains elusive due to lack of longitudinal data on premorbid hypertension (HTN) and serial BP changes within an individual. Precision medicine for AIS and management of HTN requires an understanding of collateral circulation.

Methods: The Interventional Management of Stroke III angiography core lab prospectively evaluated collateral circulation utilizing the ASITN scale prior to endovascular therapy. We used these data to discern the relationship of clinical and imaging markers of premorbid HTN with acute, serial BP measures and collaterals.

Results: Collaterals at angiography were graded in 276/331 (83%) subjects. Higher initial BP was associated with impaired collateral status, driven by diastolic BP (ASITN 0-1: mean 88.9 ± 23.5 mmHg (n=70); 2: 82.7 ± 18.5 mmHg (n=106); 3-4: 79.4 ± 15.0 mmHg (n=95); p=0.002) but not systolic BP (ASITN 0-1: mean 153.7 ± 31.5 mmHg (n=71); 2: 147.8 ± 29.0 mmHg (n=107); 3-4: 146.8 ± 28.3 mmHg (n=95); p=0.153). Premorbid HTN was linked with worse collaterals (ASITN 0-1: 88.9% (64/72); 2: 78.7% (85/108); 3-4: 64.2% (61/95); p=0.001). Admission anti-hypertensive medications were tied to worse collaterals (ASITN 0-1: 76.4% (55/72); 2: 64.8% (70/108); 3-4: 57.3% (55/96); p=0.036). Prior infarction on baseline imaging was also a marker of worse collaterals (ASITN 0-1: 33.3% (24/72); 2: 24.3% (26/107); 3-4: 19.1% (18/94); p=0.039). Serial BP from pre-randomization to post-tPA, however, was unrelated to collateral status. Multivariate modeling to predict collateral grade revealed that history of HTN (OR 0.29 95%CI (0.13, 0.64); p=0.002) and diastolic BP measured post-stroke but pre-randomization (per 10 mm Hg) (OR 0.80 95%CI (0.69, 0.93); p=0.004) were both distinct markers of impaired collaterals. The poorest collaterals were seen in those with both history of HTN and acutely elevated BP.

Conclusions: Chronic and acute HTN are both potent predictors of impaired collaterals in AIS. Understanding how HTN affects the structure and function of collaterals and response to acute BP changes is critical for future hypertensive management and collateral augmentation.

Observed Cost and Variations in Short Term Cost-Effectiveness of Therapy for Ischemic Stroke in Interventional Management of Stroke (IMS) III

Background

Examination of linked data on patient outcomes and cost of care may help identify areas where stroke care can be improved. We report on the association between variations in stroke severity, patient outcomes, cost, and treatment patterns observed over the acute hospital stay and through the 12‐month follow‐up for subjects receiving endovascular therapy compared to intravenous tissue plasminogen activator alone in the IMS (Interventional Management of Stroke) III Trial.

Methods and Results

Prospective data collected for a prespecified economic analysis of the trial were used. Data included hospital billing records for the initial stroke admission and subsequent detailed resource use after the acute hospitalization collected at 3, 6, 9, and 12 months. Cost of follow‐up care varied 6‐fold for patients in the lowest (0–1) and highest (20+) National Institutes of Health Stroke Scale category at 5 days, and by modified Rankin Scale at 3 months. The kind of resources used postdischarge also varied between treatment groups. Incremental short‐term cost‐effectiveness ratios varied greatly when treatments were compared for patient subgroups. Patient subgroups predefined by stroke severity had incremental cost‐effectiveness ratios of $97 303/quality‐adjusted life year (severe stroke) and $3 187 805/quality‐adjusted life year (moderately severe stroke).

Conclusions

Detailed economic and resource utilization data from IMS III provide powerful evidence for the large effect that patient outcome has on the economic value of medical and endovascular reperfusion therapies. These data can be used to inform process improvements for stroke care and to estimate the cost‐effectiveness of endovascular therapy in the US health system for stroke intervention trials.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Registration number: NCT00359424.

Fluid-Signal Structures in the Cervical Spinal Cord on MRI: Anterior Median Fissure versus Central Canal

BACKGROUND AND PURPOSE

Hyperintense fluid-signal anterior median fissure and hyperintense foci resembling the central canal are seen on cervical spine axial T2 MR imaging. They may also be associated with a channel-like T2-hyperintense craniocaudad line on sagittal images. We hypothesized that the hyperintense foci and the sagittal line may represent the base of the anterior median fissure.

MATERIALS AND METHODS

In this exploratory study, 358 cervical MR images were analyzed for recording and comparing the incidence/numbers of hyperintense foci, anterior median fissure, and sagittal line as hyperintense foci, anterior median fissure, and sagittal line per patient when present alone or together, both with and without the sagittal line.

RESULTS

Hyperintense foci were identified on 238/358 (66.5%) studies; an anterior median fissure, on 218/358 (60.9%). The hyperintense foci/anterior median fissure ratio was 3.7/2.3 (P = .00001). Anterior median fissures were seen alone less commonly than hyperintense foci were seen alone (P = .045). We identified increased anterior median fissure/patient in a hyperintense foci +anterior median fissure group compared with an anterior median fissure-only group (4.0 versus 3.2, P = .05), with similar hyperintense foci/patient in the hyperintense foci+anterior median fissure and hyperintense foci-only groups (5.5 versus 5.8, P = .35), and proportional distribution of both across the hyperintense foci+anterior median fissure subgroups (hyperintense foci/anterior median fissure ratio, 1.3). The sagittal line in 89 (24.9%) patients was associated with increased hyperintense foci and anterior median fissure/patient. Greater correlation of anterior median fissure/patient to sagittal line presence was seen in sagittal line subgroup analysis.

CONCLUSIONS

This exploratory analysis found an increased anterior median fissure per patient in conjunction with hyperintense foci presence, a proportional increase of both across the hyperintense foci+anterior median fissure group, and greater correlation of anterior median fissure per patient with the sagittal line. These findings suggest that anterior median fissure and hyperintense foci are structurally related, that hyperintense foci may commonly be the base of the anterior median fissure, and that the sagittal line is a manifestation primarily of an anterior median fissure, occasionally appearing as channels that may simulate the central canal.

Severe carotid stenosis and delay of reperfusion in endovascular stroke treatment: an Interventional Management of Stroke-III study

OBJECTIVE The impact of extracranial carotid stenosis on interventional revascularization of acute anterior circulation stroke is unknown. The authors examined the effects of high-grade carotid stenosis on the results of endovascular treatment of patients in the Interventional Management of Stroke (IMS)-III trial. METHODS The 278 patients in the endovascular arm of the IMS-III trial were categorized according to the degree of carotid stenosis as determined by angiography. In comparing patients with severe stenosis or occlusion (≥ 70%) to those without severe stenosis (< 70%), the authors evaluated the time to endovascular reperfusion, modified Thrombolysis in Cerebrovascular Infarction (mTICI) scores, 24-hour mean infarct volumes, symptomatic intracerebral hemorrhage rates, and modified Rankin Scale (mRS) scores at 90 days. RESULTS Compared with the 249 patients with less than 70% stenosis, patients with severe stenosis (n = 29) were found to have a significantly longer mean time to reperfusion (105.7 vs 77.7 minutes, p = 0.004); differences in mTICI scores, infarct volumes, hemorrhage rates, and mRS scores at 90 days did not reach statistical significance. Multiple regression analysis revealed that severe carotid stenosis (p < 0.0001) and higher baseline National Institutes of Health Stroke Scale (NIHSS) scores (p = 0.004) were associated with an increase in time to reperfusion. Older age (p < 0.0001), higher NIHSS score (p < 0.0001), and the absence of reperfusion (p = 0.001) were associated with worse clinical outcomes. CONCLUSIONS Severe ipsilateral ICA stenosis was associated with a significantly longer time to reperfusion in the IMS-III trial. Although these findings may not translate directly to modern devices, this 28-minute delay in reperfusion has significant implications, raising concern over the treatment of tandem ICA stenosis and downstream large-vessel occlusion.

Endovascular Therapy of M2 Occlusion in IMS III: Role of M2 Segment Definition and Location on Clinical and Revascularization Outcomes

BACKGROUND AND PURPOSE

Uncertainty persists regarding the safety and efficacy of endovascular therapy of M2 occlusions following IV tPA. We reviewed the impact of revascularization on clinical outcomes in 83 patients with M2 occlusions in the Interventional Management of Stroke III trial according to specific M1-M2 segment anatomic features.

MATERIALS AND METHODS

Perfusion of any M2 branch distinguished M2-versus-M1 occlusion. Prespecified modified TICI and arterial occlusive lesion revascularization and clinical mRS 0-2 end points at 90 days for endovascular therapy-treated M2 occlusions were analyzed. Post hoc analyses of the relationship of outcomes to multiple baseline angiographic M2 and M1 subgroup characteristics were performed.

RESULTS

Of 83 participants with M2 occlusion who underwent endovascular therapy, 41.0% achieved mRS 0-2 at 90 days, including 46.6% with modified TICI 2-3 reperfusion compared with 26.1% with modified TICI 0-1 reperfusion (risk difference, 20.6%; 95% CI, -1.4%-42.5%). mRS 0-2 outcome was associated with reperfusion for M2 trunk (n = 9) or M2 division (n = 42) occlusions, but not for M2 branch occlusions (n = 28). Of participants with trunk and division occlusions, 63.2% with modified TICI 2a and 42.9% with modified TICI 2b reperfusion achieved mRS 0-2 outcomes; mRS 0-2 outcomes for M2 trunk occlusions (33%) did not differ from distal (38.2%) and proximal (26.9%) M1 occlusions.

CONCLUSIONS

mRS 0-2 at 90 days was dependent on reperfusion for M2 trunk but not for M2 branch occlusions. For M2 division occlusions, good outcome with modified TICI 2b reperfusion did not differ from that in modified TICI 2a. M2 segment definition and occlusion location may contribute to differences in revascularization and good outcome between Interventional Management of Stroke III and other endovascular therapy studies.

Recanalization and Angiographic Reperfusion Are Both Associated with a Favorable Clinical Outcome in the IMS III Trial

BACKGROUND

Prompt revascularization is the main goal of acute ischemic stroke treatment. We examined which revascularization scale - reperfusion (modified Treatment in Cerebral Infarctions, mTICI) or recanalization (Arterial Occlusive Lesion, AOL) - better predicted the clinical outcome in ischemic stroke participants treated with endovascular therapy (EVT). Additionally, we determined the optimal thresholds for the predictive accuracy of each scale.

METHODS

We included participants from the Interventional Management of Stroke (IMS) III trial with complete occlusion in the internal carotid artery terminus or proximal middle cerebral artery (M1 or M2) who completed EVT within 7 h of symptom onset. The abilities of the AOL and mTICI scales to predict a favorable outcome (defined as a modified Rankin Scale score of 0-2 at 3 months) were compared by receiver operating characteristic analyses. The maximal sensitivity and specificity for each revascularization scale were established.

RESULTS

Among 240 participants who met the study inclusion criteria, 79 (33%) achieved a favorable outcome. Higher scores of mTICI and AOL increased the likelihood of a favorable outcome (2.7% with mTICI 0 vs. 83.3% with mTICI 3, and 3.0% with AOL 0 vs. 43% with AOL 3). The accuracy of mTICI reperfusion and AOL recanalization for a favorable outcome prediction was similar, with optimal thresholds of mTICI 2b/3 and AOL 3, respectively.

CONCLUSION

Reperfusion (mTICI) and recanalization (AOL) predicted a favorable clinical outcome with comparable accuracy in ischemic stroke participants treated with EVT. Optimal revascularization goals to maximize clinical outcome (modified Rankin Scale score of 0-2) consisted of complete recanalization (AOL 3) and reperfusion of at least 50% of the arterial tree of the symptomatic artery (mTICI 2b/3) in the IMS III trial setting.

Multimodal CT Imaging: Time to Treatment and Outcomes in the IMS III Trial

BACKGROUND AND PURPOSE

The importance of time in acute stroke is well-established. Using the Interventional Management of Stroke III trial data, we explored the effect of multimodal imaging (CT perfusion and/or CT angiography) versus noncontrast CT alone on time to treatment and outcomes.

MATERIALS AND METHODS

We examined 3 groups: 1) subjects with baseline CTP and CTA (CTP+CTA), 2) subjects with baseline CTA without CTP (CTA), and 3) subjects with noncontrast head CT alone. The demographics, treatment time intervals, and clinical outcomes in these groups were studied.

RESULTS

Of 656 subjects enrolled in the Interventional Management of Stroke III trial, 90 (13.7%) received CTP and CTA, 216 (32.9%) received CTA (without CTP), and 342 (52.1%) received NCCT alone. Median times for the CTP+CTA, CTA, and NCCT groups were as follows: stroke onset to IV tPA (120.5 versus 117.5 versus 120 minutes; P = .5762), IV tPA to groin puncture (77.5 versus 81 versus 91 minutes; P = .0043), groin puncture to endovascular therapy start (30 versus 38 versus 44 minutes; P = .0001), and endovascular therapy start to end (63 versus 46 versus 74 minutes; P < .0001). Compared with NCCT, the CTA group had better outcomes in the endovascular arm (OR, 2.12; 95% CI, 1.36-3.31; adjusted for age, NIHSS score, and time from onset to IV tPA). The CTP+CTA group did not have better outcomes compared with the NCCT group.

CONCLUSIONS

Use of CTA with or without CTP did not delay IV tPA or endovascular therapy compared with NCCT in the Interventional Management of Stroke III trial.

Abstract 159: Posterior Communicating Artery Flow Diversion in Middle Cerebral Artery Stroke: Angiographic Evidence from IMS III

Background: Only 20% of adults have a “fetal” posterior communicating artery (PCOMM) with carotid flow to the posterior cerebral artery. Dynamic pressure changes at the circle of Willis due to proximal artery occlusion may restore such collateral blood flow patterns. We investigated the findings and implications of PCOMM blood flow in middle cerebral artery (MCA) stroke at angiography in IMS III.

Methods: The angiography core lab prospectively evaluated PCOMM blood flow and collateral circulation in proximal MCA or M1 occlusion. Proximal or distal M1 occlusion was noted with PCOMM flow scored (0-2) on ipsilateral carotid injections before and after endovascular therapy, correlating PCOMM status with ASITN/SIR leptomeningeal collateral grade, TICI reperfusion and subsequent clinical outcomes.

Results: 122 patients with M1 occlusion at angiography (60 proximal, 62 distal) had peri-procedural evaluation of PCOMM status and associated collateral grade. Ipsilateral carotid injections revealed PCOMM flow diversion in 87/122 (71%) prior to revascularization, including 41/60 (68%) in proximal M1 and 46/62 (74%) in distal M1 (p=0.61) occlusions. After treatment, PCOMM patency was noted in 86/122 (71%), with 40/60 (67%) in proximal M1 and 46/62 (74%) in distal M1 (p=0.48) occlusions. Decrease in PCOMM score after therapy was noted in 11/122 (9%); 9/11 (82%) had mTICI 2B-3 reperfusion compared to 48/111 (43%) mTICI 2B-3 reperfusion in those with PCOMM unchanged (p=0.03). PCOMM flow (n=85) was associated with worse ASITN/SIR collaterals (median 2, IQR 2-3) than those without (n=29; median 3, IQR 2-3), p=0.09. PCOMM patency before treatment had 90-day mRS median of 4 (2-6) versus 3 (1-4), p=0.37.

Conclusions: PCOMM flow diversion is common in MCA stroke, revealing an inverse correlation with leptomeningeal collaterals and dynamic changes following reperfusion.

Abstract WMP3: Grade 2 or Partial Collaterals in IMS III: Half Full or Half Empty?

Background: Most ischemic stroke patients have at least partial collateral filling of the ischemic territory or grade 2 collaterals, yet the temporal delay or limited spatial extent may vary considerably. We investigated the clinical implications of grade 2 (partial) versus grade 3 (complete) collaterals in the IMS III trial.

Methods: The angiography core lab in IMS III prospectively evaluated collateral circulation utilizing the ASITN/SIR definitions of grades 2 and 3. The clinical features, serial imaging findings, revascularization results and outcomes were contrasted.

Results: Of 203 M1 or intracranial ICA occlusions, ASITN/SIR collateral grades could be scored in 161 (79%) cases, including grade 0 or none (n=7), grade 1 or marginal (n=23), grade 2 or partial (n=62), grade 3 or complete but delayed (n=62) and grade 4 or early and complete (n=7) collaterals. History of hypertension (p=0.02) was more common in those with partial collaterals, whereas age, sex and other co-morbidities were similar. Initial stroke severity defined by baseline NIHSS was worse in those with partial versus complete collaterals (median 19 IQR 16-21 vs. median 17 IQR 13-20; p=0.02). Baseline ASPECTS was lower in partial versus complete collaterals (median 7 IQR 5-9 vs. median 8 IQR 7-10; p=0.04). Successful reperfusion (mTICI 2B-3) was markedly less frequent (16% vs. 44%, p<0.001), despite equivalent recanalization of primary vessel occlusions (AOL 2-3) (49% vs. 54%, p=0.34). ASPECTS at 24 hours was much lower in partial versus complete collaterals (median 3 IQR 1-5 vs. median 6 IQR 3-7; p<0.001), with greater ASPECTS decline (median 4 IQR 2-5 vs. median 2 IQR 1-4; p=0.002) even after successful reperfusion (median 3.5 IQR 1-4.5 vs. median 2 IQR 1-4; p=0.22). 90-day mRS was notably worse in those with partial collaterals (median 4 IQR 3-6 vs. median 2 IQR 1-4; p<0.001) with fewer good clinical outcomes (12% mRS 0-2 vs. 32%, p<0.001) and greater mortality (19% vs. 5%, p=0.003).

Conclusions: Grade 2 or partial collaterals have radically distinct imaging and clinical implications in the setting of endovascular stroke therapy.

Outcome Differences between Intra-Arterial Iso- and Low-Osmolality Iodinated Radiographic Contrast Media in the Interventional Management of Stroke III Trial

BACKGROUND AND PURPOSE

Intracarotid arterial infusion of nonionic, low-osmolal iohexol contrast medium has been associated with increased intracranial hemorrhage in a rat middle cerebral artery occlusion model compared with saline infusion. Iso-osmolal iodixanol (290 mOsm/kg H2O) infusion demonstrated smaller infarcts and less intracranial hemorrhage compared with low-osmolal iopamidol and saline. No studies comparing iodinated radiographic contrast media in human stroke have been performed, to our knowledge. We hypothesized that low-osmolal contrast media may be associated with worse outcomes compared with iodixanol in the Interventional Management of Stroke III Trial (IMS III).

MATERIALS AND METHODS

We reviewed prospective iodinated radiographic contrast media data for 133 M1 occlusions treated with endovascular therapy. We compared 5 prespecified efficacy and safety end points (mRS 0-2 outcome, modified TICI 2b-3 reperfusion, asymptomatic and symptomatic intracranial hemorrhage, and mortality) between those receiving iodixanol (n = 31) or low-osmolal contrast media (n = 102). Variables imbalanced between iodinated radiographic contrast media types or associated with outcome were considered potential covariates for the adjusted models. In addition to the iodinated radiographic contrast media type, final covariates were those selected by using the stepwise method in a logistic regression model. Adjusted relative risks were then estimated by using a log-link regression model.

RESULTS

Of baseline or endovascular therapy variables potentially linked to outcome, prior antiplatelet agent use was more common and microcatheter iodinated radiographic contrast media injections were fewer with iodixanol. Relative risk point estimates are in favor of iodixanol for the 5 prespecified end points with M1 occlusion. The percentage of risk differences are numerically greater for microcatheter injections with iodixanol.

CONCLUSIONS

While data favoring the use of iso-osmolal iodixanol for reperfusion of M1 occlusion following IV rtPA are inconclusive, potential pathophysiologic mechanisms suggesting clinical benefit warrant further investigation.

Endovascular Therapy Is Effective and Safe for Patients With Severe Ischemic Stroke: Pooled Analysis of Interventional Management of Stroke III and Multicenter Randomized Clinical Trial of Endovascular Therapy for Acute Ischemic Stroke in the Netherlands Data

BACKGROUND AND PURPOSE

We assessed the effect of endovascular treatment in acute ischemic stroke patients with severe neurological deficit (National Institutes of Health Stroke Scale score, ≥20) after a prespecified analysis plan.

METHODS

The pooled analysis of the Interventional Management of Stroke III (IMS III) and Multicenter Randomized Clinical Trial of Endovascular Therapy for Acute Ischemic Stroke in the Netherlands (MR CLEAN) trials included participants with an National Institutes of Health Stroke Scale score of ≥20 before intravenous tissue-type plasminogen activator (tPA) treatment (IMS III) or randomization (MR CLEAN) who were treated with intravenous tPA ≤3 hours of stroke onset. Our hypothesis was that participants with severe stroke randomized to endovascular therapy after intravenous tPA would have improved 90-day outcome (distribution of modified Rankin Scale scores), when compared with those who received intravenous tPA alone.

RESULTS

Among 342 participants in the pooled analysis (194 from IMS III and 148 from MR CLEAN), an ordinal logistic regression model showed that the endovascular group had superior 90-day outcome compared with the intravenous tPA group (adjusted odds ratio, 1.78; 95% confidence interval, 1.20-2.66). In the logistic regression model of the dichotomous outcome (modified Rankin Scale score, 0-2, or functional independence), the endovascular group had superior outcomes (adjusted odds ratio, 1.97; 95% confidence interval, 1.09-3.56). Functional independence (modified Rankin Scale score, ≤2) at 90 days was 25% in the endovascular group when compared with 14% in the intravenous tPA group.

CONCLUSIONS

Endovascular therapy after intravenous tPA within 3 hours of symptom onset improves functional outcome at 90 days after severe ischemic stroke.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00359424 (IMS III) and ISRCTN10888758 (MR CLEAN).

A collaborative sequential meta-analysis of individual patient data from randomized trials of endovascular therapy and tPA vs. tPA alone for acute ischemic stroke: ThRombEctomy And tPA (TREAT) analysis: statistical analysis plan for a sequential meta-analysis performed within the VISTA-Endovascular collaboration

Rationale

Endovascular treatment has been shown to restore blood flow effectively. Second-generation medical devices such as stent retrievers are now showing overwhelming efficacy in clinical trials, particularly in conjunction with intravenous recombinant tissue plasminogen activator.

Aims and Design

This statistical analysis plan utilizing a novel, sequential approach describes a prospective, individual patient data analysis of endovascular therapy in conjunction with intravenous recombinant tissue plasminogen activator agreed upon by the Thrombectomy and Tissue Plasminogen Activator Collaborative Group.

Study outcomes

This protocol will specify the primary outcome for efficacy, as ‘favorable’ outcome defined by the ordinal distribution of the modified Rankin Scale measured at three-months poststroke, but with modified Rankin Scales 5 and 6 collapsed into a single category. The primary analysis will aim to answer the questions: ‘what is the treatment effect of endovascular therapy with intravenous recombinant tissue plasminogen activator compared to intravenous tissue plasmi-nogen activator alone on full scale modified Rankin Scale at 3 months?’ and ‘to what extent do key patient characteristics influence the treatment effect of endovascular therapy?’. Key secondary outcomes include effect of endovascular therapy on death within 90 days; analyses of modified Rankin Scale using dichotomized methods; and effects of endovascular therapy on symptomatic intracranial hemorrhage. Several secondary analyses will be considered as well as expanding patient cohorts to intravenous recombinant tissue plasminogen activator-ineligible patients, should data allow.

Discussion

This collaborative meta-analysis of individual participant data from randomized trials of endovascular therapy vs. control in conjunction with intravenous thrombolysis will demonstrate the efficacy and generalizability of endovascular therapy with intravenous thrombolysis as a concomitant medication.

Relative Influence of Capillary Index Score, Revascularization, and Time on Stroke Outcomes From the Interventional Management of Stroke III Trial

BACKGROUND AND PURPOSE

Until recently, acute ischemic stroke (AIS) trials have failed to show a benefit of endovascular therapy compared with standard therapy, leading some authors to recommend decreasing the time from ictus to revascularization to improve outcomes. We hypothesize that improving patient selection using the capillary index score (CIS) may also be a useful strategy.

METHODS

CIS was calculated, blinded to outcome, from pretreatment diagnostic cerebral angiograms for 78 subjects in the Interventional Management of Stroke III database with internal carotid artery and middle cerebral artery trunk occlusion. The CIS was dichotomized into favorable (fCIS=2 or 3) and poor (pCIS=0 or 1). Outcomes were categorized based on the modified Rankin Scale score at 90 days (0-2 considered a good outcome). Modified thrombolysis in cerebral infarction score 2b or 3 was considered good revascularization. Multivariable logistic regression was performed to relate CIS, time from ictus to revascularization, modified thrombolysis in cerebral infarction score, and National Institue of Health Stroke Scale score to good outcomes.

RESULTS

Only CIS and modified thrombolysis in cerebral infarction scores were correlated with good outcomes (P<0.01). Patients with fCIS and good revascularization achieved 71% modified Rankin Scale≤2, compared with 13% for patients with pCIS and good revascularization.

CONCLUSIONS

In this subset of patients from the Interventional Management of Stroke III Trial, CIS and modified thrombolysis in cerebral infarction were strong predictors of outcome after endovascular reperfusion. Using the CIS to improve patient selection could be a powerful strategy to improve rate of good outcomes in endovascular therapy. A randomized trial is needed.

CLINICAL TRIAL REGISTRATION

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

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.

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.

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 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.

Time to Angiographic Reperfusion in Acute Ischemic Stroke

Background and Purpose—

Our objective was to use decision analytic modeling to compare 2 treatment strategies of intravenous recombinant tissue-type plasminogen activator (r-tPA) alone versus combined intravenous r-tPA/endovascular therapy in a subgroup of patients with large vessel (internal carotid artery terminus, M1, and M2) occlusion based on varying times to angiographic reperfusion and varying rates of reperfusion.

Methods—

We developed a decision model using Interventional Management of Stroke (IMS) III trial data and comprehensive literature review. We performed 1-way sensitivity analyses for time to reperfusion and 2-way sensitivity for time to reperfusion and rate of reperfusion success. We also performed probabilistic sensitivity analyses to address uncertainty in total time to reperfusion for the endovascular approach.

Results—

In the base case, endovascular approach yielded a higher expected utility (6.38 quality-adjusted life years) than the intravenous-only arm (5.42 quality-adjusted life years). One-way sensitivity analyses demonstrated superiority of endovascular treatment to intravenous-only arm unless time to reperfusion exceeded 347 minutes. Two-way sensitivity analysis demonstrated that endovascular treatment was preferred when probability of reperfusion is high and time to reperfusion is small. Probabilistic sensitivity results demonstrated an average gain for endovascular therapy of 0.76 quality-adjusted life years (SD 0.82) compared with the intravenous-only approach.

Conclusions—

In our post hoc model with its underlying limitations, endovascular therapy after intravenous r-tPA is the preferred treatment as compared with intravenous r-tPA alone. However, if time to reperfusion exceeds 347 minutes, intravenous r-tPA alone is the recommended strategy. This warrants validation in a randomized, prospective trial among patients with large vessel occlusions.

Endovascular revascularization results in IMS III: intracranial ICA and M1 occlusions

BACKGROUND

Interventional Management of Stroke III did not show that combining IV recombinant tissue plasminogen activator (rt-PA) with endovascular therapies (EVTs) is better than IV rt-PA alone.

OBJECTIVE

To report efficacy and safety results for EVT of intracranial internal carotid artery (ICA) and middle cerebral artery trunk (M1) occlusion.

METHODS

Five revascularization methods for persistent occlusions after IV rt-PA treatment were evaluated for prespecified primary and secondary endpoints, after accounting for differences in key baselines variables using propensity scores. Revascularization was scored using the arterial occlusive lesion (AOL) and the modified Thrombolysis in Cerebral Ischemia (mTICI) scores.

RESULTS

EVT of 200 subjects with intracranial ICA or M1 occlusion resulted in 81.5% AOL 2-3 recanalization, in addition to 76% mTICI 2-3 and 42.5% mTICI 2b-3 reperfusion. Adverse events included symptomatic intracranial hemorrhage (SICH) (8.0%), vessel perforations (1.5%), and new emboli (14.9%). EVT techniques used were standard microcatheter n=51; EKOS n=14; Merci n=77; Penumbra n=39; Solitaire n=4; multiple n=15. Good clinical outcome was associated with both TICI 2-3 and TICI 2b-3 reperfusion. Neither modified Rankin scale (mRS) 0-2 (28.5%), nor 90-day mortality (28.5%), nor asymptomatic ICH (36.0%) differed among revascularization methods after propensity score adjustment for subjects with intracranial ICA or M1 occlusion.

CONCLUSIONS

Good clinical outcome was associated with good reperfusion for ICA and M1 occlusion. No significant differences in efficacy or safety among revascularization methods were demonstrated after adjustment. Lack of high-quality reperfusion, adverse events, and prolonged time to treatment contributed to lower-than-expected mRS 0-2 outcomes and study futility compared with IV rt-PA.

TRIAL REGISTRATION NUMBER

NCT00359424.

Evolution of practice during the Interventional Management of Stroke III Trial and implications for ongoing trials

BACKGROUND AND PURPOSE

We explored changes in the patient population and practice of endovascular therapy during the course of the Interventional Management of Stroke (IMS) III Trial.

METHODS

Changes in baseline characteristics, use of baseline CT angiography, treatment times and specifics, and outcomes were compared between the first 4 protocols and the fifth and final protocol.

RESULTS

Compared with subjects treated in the first 4 protocol versions (n=610), subjects treated in fifth and final protocol (n=46) were older (75 versus 68 years, P<0.0002) and less likely to have a pretreatment Rankin of 0 (76% versus 89%, P=0.01), were more likely to have a pretreatment CT angiography (65% versus 45%, P=0.009), had quicker median times in the endovascular arm from onset to start of intra-arterial therapy (209 versus 250 minutes, P=0.002) and to reperfusion (269 versus 344 minutes, P<0.0001), had a higher mean dose of total tissue-type plasminogen activator in the endovascular arm (74.0 versus 63.7 mg, P<0.0001), and were less likely to receive intra-arterial tissue-type plasminogen activator as part of the endovascular procedure (16% versus 44%, P=0.015). There were no significant differences in functional and safety outcomes between subjects treated in the 2 treatments arms in either the first 4 protocols or fifth protocol although the small sample size in the fifth protocol provided limited power.

CONCLUSIONS

Endovascular technology and diagnostic approaches to acute stroke patients changed substantially during the IMS III Trial. Efforts to decrease the time to delivery of endovascular therapy were successful.

Early reperfusion and clinical outcomes in patients with M2 occlusion: pooled analysis of the PROACT II, IMS, and IMS II studies

OBJECT

The role of endovascular therapy in patients with acute ischemic stroke and a solitary M2 occlusion remains unclear. Through a pooled analysis of 3 interventional stroke trials, the authors sought to analyze the impact of successful early reperfusion of M2 occlusions on patient outcome.

METHODS

Patients with a solitary M2 occlusion were identified from the Prolyse in Acute Cerebral Thromboembolism (PROACT) II, Interventional Management of Stroke (IMS), and IMS II trial databases and were divided into 2 groups: successful reperfusion (thrombolysis in cerebral infarction [TICI] 2-3) at 2 hours and failed reperfusion (TICI 0-1) at 2 hours. Baseline characteristics and clinical outcomes were compared.

RESULTS

Sixty-three patients, 40 from PROACT II and 23 from IMS and IMS II, were identified. Successful early angiographic reperfusion (TICI 2-3) was observed in 31 patients (49.2%). No statistically significant difference in the rates of intracerebral hemorrhage (60.9% vs 47.6%, p = 0.55) or mortality (19.4% vs 15.6%, p = 0.75) was observed. However, there was a trend toward higher incidence of symptomatic hemorrhage in the TICI 2-3 group (17.4% vs 0%, p = 0.11). There was also a trend toward higher baseline glucose levels in this group (151.5 mg/dl vs 129.6 mg/ dl, p = 0.09). Despite these differences, the rate of functional independence (modified Rankin Scale Score 0-2) at 3 months was similar (TICI 2-3, 58.1% vs TICI 0-1, 53.1%; p = 0.80).

CONCLUSIONS

A positive correlation between successful early reperfusion and clinical outcome could not be demonstrated for patients with M2 occlusion. Irrespective of reperfusion status, such patients have better outcomes than those with more proximal occlusions, with more than 50% achieving functional independence at 3 months.

Recanalization and clinical outcome of occlusion sites at baseline CT angiography in the Interventional Management of Stroke III trial

PURPOSE

To use baseline computed tomographic (CT) angiography to analyze imaging and clinical end points in an Interventional Management of Stroke III cohort to identify patients who would benefit from endovascular stroke therapy.

MATERIALS AND METHODS

The primary clinical end point was 90-day dichotomized modified Rankin Scale (mRS) score. Secondary end points were 90-day mRS score distribution and 24-hour recanalization. Prespecified subgroup was baseline proximal occlusions (internal carotid, M1, or basilar arteries). Exploratory analyses were subsets with any occlusion and specific sites of occlusion (two-sided α = .01).

RESULTS

Of 656 subjects, 306 (47%) underwent baseline CT angiography or magnetic resonance angiography. Of 306, 282 (92%) had arterial occlusions. At baseline CT angiography, proximal occlusions (n = 220) demonstrated no difference in primary outcome (41.3% [62 of 150] endovascular vs 38% [27 of 70] intravenous [IV] tissue-plasminogen activator [tPA]; relative risk, 1.07 [99% confidence interval: 0.67, 1.70]; P = .70); however, 24-hour recanalization rate was higher for endovascular treatment (n = 167; 84.3% [97 of 115] endovascular vs 56% [29 of 52] IV tPA; P < .001). Exploratory subgroup analysis for any occlusion at baseline CT angiography did not demonstrate significant differences between endovascular and IV tPA arms for primary outcome (44.7% [85 of 190] vs 38% [35 of 92], P = .29), although ordinal shift analysis of full mRS distribution demonstrated a trend toward more favorable outcome (P = .011). Carotid T- or L-type occlusion (terminal internal carotid artery [ICA] with M1 middle cerebral artery and/or A1 anterior cerebral artery involvement) or tandem (extracranial or intracranial) ICA and M1 occlusion subgroup also showed a trend favoring endovascular treatment over IV tPA alone for primary outcome (26% [12 of 46] vs 4% [one of 23], P = .047).

CONCLUSION

Significant differences were identified between treatment arms for 24-hour recanalization in proximal occlusions; carotid T- or L-type and tandem ICA and M1 occlusions showed greater recanalization and a trend toward better outcome with endovascular treatment. Vascular imaging should be mandated in future endovascular trials to identify such occlusions. Online supplemental material is available for this article.

Capillary Index Score in the Interventional Management of Stroke trials I and II

BACKGROUND AND PURPOSE

The Capillary Index Score (CIS) is a simple angiography-based scale for assessing viable tissue in the ischemic territory. We retrospectively applied it to Interventional Management of Stroke (IMS) trials I and II to evaluate the predictive value for good outcomes.

METHODS

CIS was calculated from pretreatment diagnostic cerebral angiograms blinded to outcome. IMS I and II diagnostic cerebral angiogram images of sufficient quality were reviewed and CIS calculated for treated subjects with internal carotid artery or M1 occlusion. CIS scoring (0-3) was dichotomized into favorable (f CIS; 2 or 3) and poor (p CIS; 0 or 1). Modified thrombolysis in cerebral infarction score 2b or 3 was considered good revascularization. CIS and modified thrombolysis in cerebral infarction scores were compared with good outcome, defined as modified Rankin Scale score≤2 at 90 days.

RESULTS

Twenty-eight of 161 subjects met the inclusion criteria. Thirteen (46%) had f CIS. Good clinical outcome was significantly different between the 2 CIS groups (62% for f CIS versus 7% for p CIS; P=0.004). Good reperfusion correlated to good outcome (P=0.04). No significant differences in time to intravenous or intra-arterial treatment were identified between f CIS and p CIS groups (P>0.25).

CONCLUSIONS

A f CIS was found in ≈50% of subjects and was a virtual prerequisite for good outcome in this study subgroup of IMS I and II. We call this the 50% barrier.

Time to angiographic reperfusion and clinical outcome after acute ischaemic stroke: an analysis of data from the Interventional Management of Stroke (IMS III) phase 3 trial

BACKGROUND

The IMS III trial did not show a clinical benefit of endovascular treatment compared with intravenous alteplase (recombinant tissue plasminogen activator) alone for moderate or severe ischaemic strokes. Late reperfusion of tissue that was no longer salvageable could be one explanation, as suggested by previous exploratory studies that showed an association between time to reperfusion and good clinical outcome. We sought to validate this association in a preplanned analysis of data from the IMS III trial.

METHODS

We used data for patients with complete proximal arterial occlusions in the anterior circulation who received endovascular treatment and achieved angiographic reperfusion (score on Thrombolysis in Cerebral Infarction scale of grade 2-3) during the endovascular procedure (within 7 h of symptom onset). We used logistic regression to model good clinical outcome (defined as a modified Rankin Scale score of 0-2 at 3 months) as a function of the time to reperfusion. We prespecified variables to be considered for adjustment, including age, baseline National Institutes of Health Stroke Scale score, sex, and baseline blood glucose concentration.

FINDINGS

Of 240 patients who were otherwise eligible for inclusion in our analysis, 182 (76%) achieved angiographic reperfusion. Mean time from symptom onset to reperfusion (ie, procedure end) was 325 min (SD 52). Increased time to reperfusion was associated with a decreased likelihood of good clinical outcome (unadjusted relative risk for every 30-min delay 0·85 [95% CI 0·77-0·94]; adjusted relative risk 0·88 [0·80-0·98]).

INTERPRETATION

Delays in time to angiographic reperfusion lead to a decreased likelihood of good clinical outcome in patients after moderate to severe stroke. Rapid reperfusion could be crucial for the success of future acute endovascular trials.

FUNDING

US National Institutes of Health and National Institute of Neurological Disorders and Stroke.

Abstract W P19: Propensity Scores Facilitate Unbiased Comparison of Endovascular Devices in IMS III

Introduction: The IMS III Trial randomized acute ischemic stroke patients to endovascular (IV tPA + intra-arterial) or IV tPA -only therapy to compare efficacy. However, endovascular subjects were not randomized to a particular approach; interventionalists chose the method. Hence, any statistical comparison of devices must account for potential selection bias.

Methods: To compare the efficacy and safety of various endovascular treatment modalities, the multiple propensity score (PS) method was implemented to account for potential bias and achieve balance between groups. The analysis is restricted to subjects with an ICA or M1 vessel treated using a standard microcatheter, the Merci retriever, or the Penumbra system. Propensity scores were estimated via a multinomial regression model that included demographic and clinical variables for which 1) an imbalance between devices was demonstrated (α=0.10) or 2) an association with outcome was established (α=0.10). PS tertiles were included as covariates in a logistic regression model relating outcome to device.

Results: The analysis included 167 subjects treated with a standard microcatheter (n=51), the Merci retriever (n=77) or the Penumbra system (n=39). Unadjusted comparison indicated imbalance between devices in the presence of atrial fibrillation, age, systolic blood pressure, onset to IV tPA start time, and IV tPA start to groin puncture time. Additional covariates included in the PS model varied by outcome. After adjustment for PS tertiles, the initial difference in baseline variables between devices was no longer statistically significant and there was insufficient evidence to conclude that the devices differed for any of the outcomes considered.

Conclusions: Selection bias was a concern in comparing endovascular approaches in IMS III. The PS method successfully balanced baseline characteristics and facilitated a valid conclusion: major efficacy and safety outcomes did not significantly differ between subjects treated with a standard microcatheter, the Merci retriever, and the Penumbra system. Limitations include small sample size and the possibility of differences in unmeasured baseline characteristics.

Abstract 74: Early Arterial Recanalization After Intra-venous Tissue-Plasminogen-Activator Treatment in the Interventional Management of Stroke-3 Study

Background: Data on arterial recanalization after IV t-PA treatment are rare. IMS-3 allows the study of variables affecting arterial recanalization after IV t-PA in acute ischemic stroke patients with CTA-proved major artery occlusions.

Methods: Of 656 acute ischemic stroke patients in IMS-3, 306 were examined with baseline CTA and randomized either to IV t-PA (N=95) or to IV t-PA followed by digital subtraction angiography (DSA) and endovascular therapy (EVT) (N=211). Comparison of baseline CTA to DSA within 5 hours of stroke onset assessed early arterial recanalization after IV t-PA. A central core lab categorized DSA vessel occlusion as “no, partial, or complete”. We studied the association between arterial occlusion sites on baseline CTA with early recanalization for the endovascular group and analyzed its impact on clinical outcome at 90 days.

Results: In the EVT group, 22 patients (10.4%) had no CTA intracranial occlusions, but 1 extracranial occlusion; 42 patients (19.9%) had occlusions of intracranial internal carotid artery (ic-ICA); 10 patients (4.7%) had tandem occlusions of the cervical ICA and middle cerebral artery (MCA); 95 patients (45.0%) had MCA-trunk (M1) occlusions, 33 patients (15.6%) had M2 occlusions, 3 patients (1.4%) had M3/4 occlusions, and 6 patients (2.8%) occlusions within posterior circulation. Partial or complete recanalization occurred in 28.6% of patients before DSA and was marginally associated with occlusion site (p=0.0525) (8 patients (19.0%) with ic-ICA occlusion, 0 patients with tandem ICA/MCA occlusions, 34 patients (35.8%) with M1 occlusions, 11 patients (33.3%) with M2 occlusions, 0 patients with M3/4 occlusions, and 1 patient (16.7%) with occlusion within posterior circulation). Three CTA negative patients had intracranial occlusions on DSA. Thirty-two patients (59.3%) with early recanalization achieved mRS of 0-2 at 90 days compared to 51 patients (38.4%) without early recanalization (p=0.0099). There was no relationship between early recanalization and time to IV t-PA or mean t-PA dose.

Conclusion: Before EVT, IV rt-PA may facilitate arterial recanalization and better clinical outcome in about one third of patients.

Collaterals at angiography and outcomes in the Interventional Management of Stroke (IMS) III trial

BACKGROUND AND PURPOSE

Endovascular strategies provide unique opportunity to correlate angiographic measures of collateral circulation at the time of endovascular therapy. We conducted systematic analyses of collaterals at conventional angiography on recanalization, reperfusion, and clinical outcomes in the endovascular treatment arm of the Interventional Management of Stroke (IMS) III trial.

METHODS

Prospective evaluation of angiographic collaterals was conducted via central review of subjects treated with endovascular therapy in IMS III (n=331). Collateral grade before endovascular therapy was assessed with the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology scale, blinded to all other data. Statistical analyses investigated the association between collaterals with baseline clinical variables, angiographic measures of recanalization, reperfusion and clinical outcomes.

RESULTS

Adequate views of collateral circulation to the ischemic territory were available in 276 of 331 (83%) subjects. Collateral grade was strongly related to both recanalization of the occluded arterial segment (P=0.0016) and downstream reperfusion (P<0.0001). Multivariable analyses confirmed that robust angiographic collateral grade was a significant predictor of good clinical outcome (modified Rankin Scale score≤2) at 90 days (P=0.0353), adjusted for age, history of diabetes mellitus, National Institutes of Health Stroke Scale strata, and Alberta Stroke Program Early CT Score. The relationship between collateral flow and clinical outcome may depend on the degree of reperfusion.

CONCLUSIONS

More robust collateral grade was associated with better recanalization, reperfusion, and subsequent better clinical outcomes. These data, from the largest endovascular trial to date, suggest that collaterals are an important consideration in future trial design.

CLINICAL TRIAL REGISTRATION URL

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

Alberta Stroke Program early computed tomography score to select patients for endovascular treatment: Interventional Management of Stroke (IMS)-III Trial

BACKGROUND AND PURPOSE

The Interventional Management of Stroke (IMS)-III trial randomized patients with acute ischemic stroke to intravenous tissue-type plasminogen activator (tPA) plus endovascular therapy versus intravenous tPA therapy alone within 3 hours from symptom onset. A predefined secondary hypothesis was that subjects with significant early ischemic change on the baseline scan would not respond to endovascular therapy.

METHODS

The primary outcome was 90-day modified Rankin Scale score 0 to 2. The baseline and follow-up computed tomographic (CT) scan images were reviewed centrally and blinded to any clinical information. We assessed whether the baseline Alberta Stroke Program Early CT Score (ASPECTS) predicted outcome and interacted with study treatment. We analyzed subgroups defined by time from onset to intravenous tPA initiation and baseline occlusion status at a prespecified α=0.01.

RESULTS

Baseline demographic and clinical characteristics of 656 randomized patients were similar between subjects with a baseline ASPECTS 8 to 10 (58% of the study sample) versus 0 to 7. Subjects with ASPECTS 8 to 10 were almost twice as likely (relative risk, 1.8; 99% confidence interval, 1.4-2.4) to achieve a favorable outcome. There was insufficient evidence of a treatment-by-ASPECTS interaction. In those treated with onset to intravenous tPA <120 minutes, in CT angiography-proven internal carotid artery or middle cerebral artery occlusion, and in both, results were similar. The probability of achieving recanalization (arterial occlusion lesion, 2-3) of the primary arterial occlusive lesion (relative risk, 1.3; 99% confidence interval, 1.0-1.8) or achieving thrombolysis in cerebral ischemia score 2b/3 reperfusion (relative risk 2.0; 99% confidence interval, 1.2-3.2) was higher among subjects with higher ASPECTS.

CONCLUSIONS

ASPECTS is a strong predictor of outcome and a predictor of reperfusion. ASPECTS did not identify a subpopulation of subjects that particularly benefitted from endovascular therapy immediately after routine intravenous tPA.

CLINICAL TRIAL REGISTRATION URL

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

Combined approach to lysis utilizing eptifibatide and recombinant tissue plasminogen activator in acute ischemic stroke-enhanced regimen stroke trial

BACKGROUND AND PURPOSE

In a previous study, 0.3 and 0.45 mg/kg of intravenous recombinant tissue plasminogen activator (rt-PA) were safe when combined with eptifibatide 75 mcg/kg bolus and a 2-hour infusion (0.75 mcg/kg per minute). The Combined Approach to Lysis Utilizing Eptifibatide and rt-PA in Acute Ischemic Stroke-Enhanced Regimen (CLEAR-ER) trial sought to determine the safety of a higher-dose regimen and to establish evidence for a phase III trial.

METHODS

CLEAR-ER was a multicenter, double-blind, randomized safety study. Ischemic stroke patients were randomized to 0.6 mg/kg rt-PA plus eptifibatide (135 mcg/kg bolus and a 2-hour infusion at 0.75 mcg/kg per minute) versus standard rt-PA (0.9 mg/kg). The primary safety end point was the incidence of symptomatic intracranial hemorrhage within 36 hours. The primary efficacy outcome measure was the modified Rankin Scale (mRS) score ≤1 or return to baseline mRS at 90 days. Analysis of the safety and efficacy outcomes was done with multiple logistic regression.

RESULTS

Of 126 subjects, 101 received combination therapy, and 25 received standard rt-PA. Two (2%) patients in the combination group and 3 (12%) in the standard group had symptomatic intracranial hemorrhage (odds ratio, 0.15; 95% confidence interval, 0.01-1.40; P=0.053). At 90 days, 49.5% of the combination group had mRS ≤1 or return to baseline mRS versus 36.0% in the standard group (odds ratio, 1.74; 95% confidence interval, 0.70-4.31; P=0.23). After adjusting for age, baseline National Institutes of Health Stroke Scale, time to intravenous rt-PA, and baseline mRS, the odds ratio was 1.38 (95% confidence interval, 0.51-3.76; P=0.52).

CONCLUSIONS

The combined regimen of intravenous rt-PA and eptifibatide studied in this trial was safe and provides evidence that a phase III trial is warranted to determine efficacy of the regimen.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00894803.

Endovascular therapy after intravenous t-PA versus t-PA alone for stroke

BACKGROUND

Endovascular therapy is increasingly used after the administration of intravenous tissue plasminogen activator (t-PA) for patients with moderate-to-severe acute ischemic stroke, but whether a combined approach is more effective than intravenous t-PA alone is uncertain.

METHODS

We randomly assigned eligible patients who had received intravenous t-PA within 3 hours after symptom onset to receive additional endovascular therapy or intravenous t-PA alone, in a 2:1 ratio. The primary outcome measure was a modified Rankin scale score of 2 or less (indicating functional independence) at 90 days (scores range from 0 to 6, with higher scores indicating greater disability).

RESULTS

The study was stopped early because of futility after 656 participants had undergone randomization (434 patients to endovascular therapy and 222 to intravenous t-PA alone). The proportion of participants with a modified Rankin score of 2 or less at 90 days did not differ significantly according to treatment (40.8% with endovascular therapy and 38.7% with intravenous t-PA; absolute adjusted difference, 1.5 percentage points; 95% confidence interval [CI], -6.1 to 9.1, with adjustment for the National Institutes of Health Stroke Scale [NIHSS] score [8-19, indicating moderately severe stroke, or ≥20, indicating severe stroke]), nor were there significant differences for the predefined subgroups of patients with an NIHSS score of 20 or higher (6.8 percentage points; 95% CI, -4.4 to 18.1) and those with a score of 19 or lower (-1.0 percentage point; 95% CI, -10.8 to 8.8). Findings in the endovascular-therapy and intravenous t-PA groups were similar for mortality at 90 days (19.1% and 21.6%, respectively; P=0.52) and the proportion of patients with symptomatic intracerebral hemorrhage within 30 hours after initiation of t-PA (6.2% and 5.9%, respectively; P=0.83).

CONCLUSIONS

The trial showed similar safety outcomes and no significant difference in functional independence with endovascular therapy after intravenous t-PA, as compared with intravenous t-PA alone. (Funded by the National Institutes of Health and others; ClinicalTrials.gov number, NCT00359424.).

Abstract WP5: Collaterals in the Interventional Management of Stroke (IMS) III Trial

Background: Collateral circulation may exert an influential effect on arterial recanalization, downstream angiographic and tissue reperfusion and ensuing clinical outcomes after revascularization for acute ischemic stroke. Endovascular strategies provide unique opportunity to correlate definitive angiographic measures of collaterals at the time of interventional therapy. We conducted a systematic analysis of collaterals on conventional angiography in the endovascular treatment arm of the Interventional Management of Stroke (IMS) III trial.

Methods: Prospective evaluation of angiographic collaterals was conducted via central review of all cases enrolled and treated in the endovascular arm of IMS III. Collateral grade was assessed with the ASITN/SIR scale on angiography at procedure start and immediately prior to intra-arterial treatment (time 0), blind to all other data. Statistical analyses investigated the association between collateral grade with baseline clinical data, angiographic measures of recanalization (AOL), angiographic reperfusion (TICI), and clinical outcomes.

Results: From 2006-2012, 380 cases were prospectively evaluated for collateral grade at start of procedure and time 0 prior to treatment. Adequate collateral views were available in 283/380 (75%) cases at baseline, and 277/380 (73%) cases at time 0 and after subsequent treatment with intra-arterial tPA, EKOS, MERCI, Penumbra, and Solitaire devices. Detailed results will be presented at ISC in coordination with release of the primary trial results. The relationships between collateral flow grade and baseline clinical features (NIHSS and age), location of vascular occlusion at cerebral angiography, AOL recanalization and TICI reperfusion, and mROS of 0-2 at 90 days will be presented. Analyses will explore potential interactions between collateral flow grade with recanalization, angiographic reperfusion, and clinical outcome.

Conclusions: Collateral circulation was available and prospectively evaluated in the largest endovascular therapy trial for stroke conducted to date. The role of collaterals may be an important consideration in the design of future endovascular trials.

Abstract TP28: Combining Clinical with Radiographic Criteria to Select Patients for Endovascular Therapy in Acute Stroke

BACKGROUND: Patient selection is emerging as an important aspect of interventional treatment of acute ischemic stroke. The baseline CT scan and NIHSS can be performed very quickly to identify those patients who will have proximal arterial occlusions (PAOs) amenable to endovascular therapy. Hyperdense arteries (HDAs) identified on thin-slice reconstruction (0.625 mm slice) CT have been shown to predict PAOs on CT Angiography. We sought to determine whether the combination of clinical (NIHSS strata) and radiographic (standard 5mm slice non-contrast head CT) criteria could better identify ideal candidates for endovascular therapy.

METHODS: We reviewed IMS I and II subjects who were treated with IV tPA for an anterior circulation stroke, and had a baseline standard head CT followed by a digital subtraction angiogram (DSA; n = 144 of the 161 patients in IMS I and II). Stroke severity (NIHSS 10-19, or ≥20), presence of a HDA on baseline CT (either in the ICA terminus or M1 branch of the MCA), and the location of arterial occlusions (either partial or complete) on DSA were determined. We calculated sensitivity, specificity and the positive predictive value (PPV) of stroke severity and a HDA for the presence of a PAO (ICA, M1 or M2 branches of MCA).

RESULTS: 64 of 144 patients (44%) had a NIHSS ≥20. 74 of 144 patients (51%) had a HDA on CT (39 patients or 49% with NIHSS 10-19; 35 patients or 55% with NIHSS ≥20). After IV tPA, a PAO was seen on DSA in 105 (73%) of patients. DSA showed distal or no occlusion in 39 patients (13 of whom had a HDA on CT). The PPV of a HDA for a PAO was 82% (95%CI = 72-90%; sens = 58%, spec = 67%), whereas the PPV of NIHSS ≥20 for a PAO was 78% (95%CI = 66-87%; sens = 48%, spec = 64%). In patients with a HDA, consideration of stroke severity (NIHSS ≥20) only improved the PPV for a PAO to 86% (95%CI = 70-95%; sens = 60%, spec = 31%). In those with a HDA and a less severe stroke (NIHSS 10-19), PPV was 79% (95%CI = 63-91%; sens = 56%, spec = 68%).

CONCLUSIONS: In patients with acute anterior circulation ischemic stroke, adding stroke severity does not appear to significantly improve the predictive value of a hyperdense artery on baseline standard CT for the presence of a proximal arterial occlusion after IV t-PA. Further study is needed to identify patients who are candidates for endovascular therapy.

Performance and training standards for endovascular acute ischemic stroke treatment

Stroke is the third leading cause of death in the United States, Canada, Europe, and Japan. According to the American Heart Association and the American Stroke Association, there are now 750,000 new strokes that occur each year, resulting in 200,000 deaths, or 1 of every 16 deaths, per year in the United States alone. Endovascular therapy for patients with acute ischemic stroke is an area of intense investigation. The American Stroke Association has given a qualified endorsement of intra-arterial thrombolysis in selected patients. Intra-arterial thrombolysis has been studied in 2 randomized trials and numerous case series. Although 2 devices have been granted FDA phase 3 approval with an indication for mechanical stroke thrombectomy, none of these thrombectomy devices has demonstrated efficacy for the improvement of patient outcomes. The purpose of the present document is to define what constitutes adequate training to perform neuroendovascular procedures in patients with acute ischemic stroke and what performance standards should be adopted to assess outcomes. These guidelines have been written and approved by multiple neuroscience societies that historically have been directly involved in the medical, surgical and endovascular care of patients with acute stroke. These organizations include the Neurovascular Coalition and its participating societies, including the Society of NeuroInterventional Surgery (SNIS), American Academy of Neurology (AAN), American Association of Neurological Surgeons/Cerebrovascular Section (AANS/CNS), and Society of Vascular & Interventional Neurology (SVIN).

Is intra-arterial thrombolysis beneficial for M2 occlusions? Subgroup analysis of the PROACT-II trial

BACKGROUND AND PURPOSE

The role of endovascular therapy for acute M2 trunk occlusions is debatable. Through a subgroup analysis of Prolyse in Acute Cerebral Thromboembolism-II, we compared outcomes of M2 occlusions in treatment and control arms.

METHODS

Solitary M2 occlusions were identified from the Prolyse in Acute Cerebral Thromboembolism-II database. Primary endpoints were successful angiographic reperfusion (TICI 2-3) at 120 minutes and functional independence (mRS 0-2) at 90 days.

RESULTS

Forty-four patients with solitary M2 occlusions, 30 in the treatment arm and 14 in the control arm, were identified. Successful reperfusion (TICI 2-3) was achieved in 53.6% and 16.7% of patients in the treatment and control arms, respectively (P=0.04). A favorable clinical outcome (mRS 0-2) was observed in 53.3% and 28.6%, respectively (P=0.19). Baseline characteristics were similar between the 2 groups.

CONCLUSIONS

Intra-arterial thrombolysis may lead to a 3-fold increase in the rate of early reperfusion of solitary M2 occlusions and could potentially double the chance of a favorable functional outcome at 90 days. Clinical Trial Registration- This trial was not registered because enrollment began before July 1, 2005.

Performance and training standards for endovascular ischemic stroke treatment

Stroke is the third leading cause of death in the USA, Canada, Europe, and Japan. According to the American Heart Association and the American Stroke Association, there are now 750,000 new strokes that occur each year, resulting in 200,000 deaths, or 1 of every 16 deaths, per year in the USA alone. Endovascular therapy for patients with acute ischemic stroke is an area of intense investigation. The American Stroke Association has given a qualified endorsement of intraarterial thrombolysis in selected patients. Intraarterial thrombolysis has been studied in two randomized trials and numerous case series. Although two devices have been granted FDA approval with an indication for mechanical stroke thrombectomy, none of these thrombectomy devices has demonstrated efficacy for the improvement of patient outcomes. The purpose of the present document is to define what constitutes adequate training to perform neuroendovascular procedures in patients with acute ischemic stroke and what performance standards should be adopted to assess outcomes. These guidelines have been written and approved by multiple neuroscience societies which historically have been directly involved in the medical, surgical and endovascular care of patients with acute stroke. The participating member organizations of the Neurovascular Coalition involved in the writing and endorsement of this document are the Society of NeuroInterventional Surgery, the American Academy of Neurology, the American Association of Neurological Surgeons/Congress of Neurological Surgeons Cerebrovascular Section, and the Society of Vascular & Interventional Neurology.

Equipoise among recanalization strategies

Modern acute ischemic stroke therapy is based on the premise that recanalization and subsequent reperfusion are essential for the preservation of brain tissue and favorable clinical outcomes. We outline key issues that we think underlie equipoise regarding the comparative clinical efficacy of IV recombinant tissue-type plasminogen activator (rt-PA) and intra-arterial (IA) reperfusion therapies for acute ischemic stroke. On the one hand, IV rt-PA therapy has the benefit of speed with presumed lower rates of recanalization of large artery occlusions as compared to IA methods. More recent reports of major arterial occlusions treated with IV rt-PA, as measured by transcranial Doppler and magnetic resonance angiography, demonstrate higher rates of recanalization. Conversely, IA therapies report higher recanalization rates, but are hampered by procedural delays and risks, even failing to be applied at all in occasional patients where time to reperfusion remains a critical factor. Higher rates of recanalization in IA trials using clot-removal devices have not translated into improved patient functional outcome as compared to trials of IV therapy. Combined IV-IA therapy promises to offer advantages of both, but perhaps only when applied in the timeliest of fashions, compared to IV therapy alone. Where equipoise exists, randomizing subjects to either IV rt-PA therapy or IV therapy followed by IA intervention, while incorporating new interventions into the study design, is a rational and appropriate research approach.

Intra-arterial iodinated radiographic contrast material injection administration in a rat middle cerebral artery occlusion and reperfusion model: possible effects on intracerebral hemorrhage

BACKGROUND AND PURPOSE

Observations in human interventional stroke treatment led us to hypothesize that iodinated radiographic contrast material use may contribute to intracerebral hemorrhage. Effects of intra-arterial iodinated radiographic contrast material on hemorrhagic transformation after middle cerebral artery occlusion and reperfusion were studied in a placebo-controlled, blinded preclinical study in rats.

METHODS

Four groups of male Sprague-Dawley rats were studied: saline group (n=8), contrast group (n=12), heparin group (n=9), and contrast+heparin group (n=9). The middle cerebral artery was occluded for 5 hours using suture placement. Heparin was infused before suture removal and reperfusion. Saline and/or contrast were infused immediately during reperfusion. Incidence, location, and size of hemorrhage were determined by brain necropsy inspection at 24 hours.

RESULTS

There was a significant increase in incidence of cortical hemorrhage from control (37.5%), contrast (75.0%), heparin (77.8%) to contrast+heparin (100%; Cochran-Mantel-Haenszel correlation, P<0.01). Both pooled contrast groups (85.7%) and pooled heparin groups (88.9%) had higher rates of cortical intracerebral hemorrhage compared with the control group (P<0.05). Similar trends for increased cortical intracerebral hemorrhage were seen in the contrast-only (P=0.18) and heparin-only (P=0.18) groups. There was a trend for decreased infarct edema in rats receiving contrast versus those without (P=0.06).

CONCLUSIONS

Intraarterial iodinated radiographic contrast material may increase cortical intracerebral hemorrhage, similar to heparin. Iodinated radiographic contrast material effect may be additive to heparin effect on the incidence of cortical intracerebral hemorrhage.

Performance and training standards for endovascular ischemic stroke treatment

Stroke is the third leading cause of death in the USA, Canada, Europe, and Japan. According to the American Heart Association and the American Stroke Association, there are now 750,000 new strokes that occur each year, resulting in 200,000 deaths, or 1 of every 16 deaths, per year in the USA alone. Endovascular therapy for patients with acute ischemic stroke is an area of intense investigation. The American Stroke Association has given a qualified endorsement of intra-arterial thrombolysis in selected patients. Intra-arterial thrombolysis has been studied in two randomized trials and numerous case series. Although two devices have been granted FDA approval with an indication for mechanical stroke thrombectomy, none of these thrombectomy devices has demonstrated efficacy for the improvement of patient outcomes. The purpose of the present document is to define what constitutes adequate training to perform neuroendovascular procedures in patients with acute ischemic stroke and what performance standards should be adopted to assess outcomes. These guidelines have been written and approved by multiple neuroscience societies which historically have been directly involved in the medical, surgical and endovascular care of patients with acute stroke. The participating member organizations of the Neurovascular Coalition involved in the writing and endorsement of this document are the Society of NeuroInterventional Surgery, the American Academy of Neurology, the American Association of Neurological Surgeons/Congress of Neurological Surgeons Cerebrovascular Section, and the Society of Vascular & Interventional Neurology.

Performance and training standards for endovascular ischemic stroke treatment

Stroke is the third-leading cause of death in the United States, Canada, Europe, and Japan. According to the American Heart Association and the American Stroke Association, 750,000 new strokes occur each year, resulting in 200,000 deaths (or 1 of every 16 deaths) per year in the United States alone. Endovascular therapy for patients with acute ischemic stroke is an area of intense investigation. The American Stroke Association has given a qualified endorsement of intra-arterial (IA) thrombolysis in selected patients. IA thrombolysis has been studied in 2 randomized trials and numerous case series. Although 2 devices have been granted FDA 3 approval with an indication for mechanical stroke thrombectomy, none of these devices has demonstrated efficacy in improving patient outcomes. This report defines what constitutes adequate training to perform neuroendovascular procedures in patients with acute ischemic stroke and identifies the performance standards that should be adopted to assess outcomes. These guidelines have been written and approved by multiple neuroscience societies that historically have been directly involved in the medical, surgical, and endovascular care of patients with acute stroke, including the Neurovascular Coalition and its participating societies: the Society of NeuroInterventional Surgery; American Academy of Neurology; American Association of Neurological Surgeons, Cerebrovascular Section; and Society of Vascular & Interventional Neurology.

Good clinical outcome after ischemic stroke with successful revascularization is time-dependent

BACKGROUND

Trials of IV recombinant tissue plasminogen activator (rt-PA) have demonstrated that longer times from ischemic stroke symptom onset to initiation of treatment are associated with progressively lower likelihoods of clinical benefit, and likely no benefit beyond 4.5 hours. How the timing of IV rt-PA initiation relates to timing of restoration of blood flow has been unclear. An understanding of the relationship between timing of angiographic reperfusion and clinical outcome is needed to establish time parameters for intraarterial (IA) therapies.

METHODS

The Interventional Management of Stroke pilot trials tested combined IV/IA therapy for moderate-to-severe ischemic strokes within 3 hours from symptom onset. To isolate the effect of time to angiographic reperfusion on clinical outcome, we analyzed only middle cerebral artery and distal internal carotid artery occlusions with successful reperfusion (Thrombolysis in Cerebral Infarction 2-3) during the interventional procedure (<7 hours). Time to angiographic reperfusion was defined as time from stroke onset to procedure termination. Good clinical outcome was defined as modified Rankin Score 0-2 at 3 months.

RESULTS

Among the 54 cases, only time to angiographic reperfusion and age independently predicted good clinical outcome after angiographic reperfusion. The probability of good clinical outcome decreased as time to angiographic reperfusion increased (unadjusted p = 0.02, adjusted p = 0.01) and approached that of cases without angiographic reperfusion within 7 hours.

CONCLUSIONS

We provide evidence that good clinical outcome following angiographically successful reperfusion is significantly time-dependent. At later times, angiographic reperfusion may be associated with a poor risk-benefit ratio in unselected patients.