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.

Endovascular therapy for ischemic stroke

The utility of intravenous tissue plasminogen activator (IV t-PA) in improving the clinical outcomes after acute ischemic stroke has been well demonstrated in past clinical trials. Though multiple initial small series of endovascular stroke therapy had shown good outcomes as compared to IV t-PA, a similar beneficial effect had not been translated in multiple randomized clinical trials of endovascular stroke therapy. Over the same time, there have been parallel advances in imaging technology and better understanding and utility of the imaging in therapy of acute stroke. In this review, we will discuss the evolution of endovascular stroke therapy followed by a discussion of the key factors that have to be considered during endovascular stroke therapy and directions for future endovascular stroke trials.

Endovascular treatment for Small Core and Anterior circulation Proximal occlusion with Emphasis on minimizing CT to recanalization times (ESCAPE) trial: methodology

ESCAPE is a prospective, multicenter, randomized clinical trial that will enroll subjects with the following main inclusion criteria: less than 12 h from symptom onset, age > 18, baseline NIHSS >5, ASPECTS score of >5 and CTA evidence of carotid T/L or M1 segment MCA occlusion, and at least moderate collaterals by CTA. The trial will determine if endovascular treatment will result in higher rates of favorable outcome compared with standard medical therapy alone. Patient populations that are eligible include those receiving IV tPA, tPA ineligible and unwitnessed onset or wake up strokes with 12 h of last seen normal. The primary end-point, based on intention-to-treat criteria is the distribution of modified Rankin Scale scores at 90 days assessed using a proportional odds model. The projected maximum sample size is 500 subjects. Randomization is stratified under a minimization process using age, gender, baseline NIHSS, baseline ASPECTS (8-10 vs. 6-7), IV tPA treatment and occlusion location (ICA vs. MCA) as covariates. The study will have one formal interim analysis after 300 subjects have been accrued. Secondary end-points at 90 days include the following: mRS 0-1; mRS 0-2; Barthel 95-100, EuroQOL and a cognitive battery. Safety outcomes are symptomatic ICH, major bleeding, contrast nephropathy, total radiation dose, malignant MCA infarction, hemicraniectomy and mortality at 90 days.

Can rt-PA be Administered to the Wrong Patient? Two Patients with Somatoform Disorder

Background:

Intravenous rt-PA (IV rt-PA) for acute stroke has raised many concerns, including its inadvertent use in patients presenting with acute stroke-like symptoms as the expression of their somatoform disorder. Diagnosis of the somatoform disorder is often delayed, and thrombolytics in these patients for their stroke-like presentation subjects them to risk for hemorrhage.

Methods:

The presentation, neurological findings, and the therapeutic decision making was audited in 85 patients who received IV rt-PA for a diagnosis of acute stroke. All the surviving patients were re-examined neurologically at least three months after IV rt-PA. Baseline and follow-up brain CT scans were re-reviewed by a neuroradiologist who was blinded to clinical presentation and outcome. Patients whose clinical presentation, brain CT and neurological outcome did not fit into known or expected anatomical and clinical patterns of stroke underwent psychological assessment using the Minnesota Multiphasic Personality Inventory-2.

Results:

In two patients three stroke-like presentations of somatoform disorder inadvertently were treated with IV rt-PA. This was primarily caused by abbreviated neurological examination and narrow differential diagnosis.

Interpretation:

Patients with somatoform disorder may present with symptoms mimicking acute stroke. Under the time constraints of IV rt-PA use, a diagnosis of somatoform disorder can be missed, subjecting such patients to the potential complications of thrombolytics.

Outcomes following sonothrombolysis in severe acute ischemic stroke: subgroup analysis of the CLOTBUST trial

BACKGROUND

Sonothrombolysis is safe and may increase the likelihood of early recanalization in acute ischemic stroke patients.

AIMS

In preparation of a phase III clinical trial, we contrast the likelihood of achieving a sustained recanalization and functional independence in a post hoc subgroup analysis of patients randomized to transcranial Doppler monitoring plus intravenous tissue plasminogen activator (sonothrombolysis) compared with intravenous tissue plasminogen activator alone in the CLOTBUST trial.

METHODS

We analyzed the data from all randomized acute ischemic stroke patients with pretreatment National Institutes of Health Stroke Scale scores ≥ 10 points and proximal intracranial occlusions in the CLOTBUST trial. We compared sustained complete recanalization rate (Thrombolysis in Brain Ischemia flow grades 4-5) and functional independence (modified Rankin Scale 0-1) at 90 days. Safety was evaluated by the rate of symptomatic intracranial hemorrhage within 72 h of stroke onset.

RESULTS

Of 126 patients, a total of 85 acute ischemic stroke patients met our inclusion criteria: mean age 71 ± 11years, 56% men, median National Institutes of Health Stroke Scale 17 (interquartile range 14-20). Of these patients, 41 (48%) and 44 (52%) were randomized to intravenous tissue plasminogen activator alone and sonothrombolysis, respectively. More patients achieved sustained complete recanalization in the sonothrombolysis than in the intravenous tissue plasminogen activator alone group (38·6% vs. 17·1%; P = 0·032). Functional independence at 90 days was more frequently achieved in the sonothrombolysis than in the intravenous tissue plasminogen activator alone group (37·2% vs. 15·8%; P = 0·045). Symptomatic intracranial hemorrhage rate was similar in both groups (4·9% vs. 4·6%; P = 1·00).

CONCLUSIONS

Our results point to a signal of efficacy and provide information to guide the subsequent phase III randomized trial of sonothrombolysis in patients with severe ischemic strokes.

Final infarct volume estimation on 1-week follow-up MR imaging is feasible and is dependent on recanalization status

PURPOSE

We aim to characterize infarct volume evolution within the first month post-ischemic stroke and to determine the effect of recanalization status on early infarct volume estimation.

METHODS

Ischemic stroke patients recruited for the MONITOR and VISION studies were retrospectively screened and patients who had infarcts on diffusion-weighted imaging (DWI) at baseline and had at least two follow-up MR scans (n = 56) were included. Pre-defined target imaging time points, obtained on a 3-T MR scanner, were 12 hours (h), 24 h, 7 days, and ≥30 days post-stroke. Infarct tissue was manually traced blinded to the images at the other time points. Infarct expansion index was calculated by dividing infarct volume at each follow-up time point by the baseline DWI infarct volume. Recanalization was assessed within 24 h post-stroke. Correlation and statistical comparison analysis were done using the Spearman, Mann-Whitney, and Kruskal-Wallis tests.

RESULTS

Follow-up infarct volumes were positively correlated with the baseline infarct volume (ρ > 0.81; p < 0.001) where the strongest correlation existed between baseline and 7-day post-stroke infarct volumes (ρ = 0.92; p < 0.001). The strongest correlation among the follow-up imaging was found between infarct volumes 7-day post-stroke and ≥30-day time points (ρ = 0.93; p < 0.001). Linear regression showed a close-to unity slope between 7-day and final infarct volumes (slope = 1.043; p < 0.001). Infarct expansion was higher in the non-recanalized group than the recanalized group at the 7-day (p = 0.001) and ≥30-day (p = 0.038) time points.

CONCLUSIONS

Final infarct volume can be approximated as early as 7 days post-stroke. Final infarct volume approximation is significantly associated with recanalization status.

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.

Observer reliability of CT angiography in the assessment of acute ischaemic stroke: data from the Third International Stroke Trial

Introduction

CT angiography (CTA) is often used for assessing patients with acute ischaemic stroke. Only limited observer reliability data exist. We tested inter- and intra-observer reliability for the assessment of CTA in acute ischaemic stroke.

Methods

We selected 15 cases from the Third International Stroke Trial (IST-3, ISRCTN25765518) with various degrees of arterial obstruction in different intracranial locations on CTA. To assess inter-observer reliability, seven members of the IST-3 expert image reading panel (>5 years experience reading CTA) and seven radiology trainees (<2 years experience) rated all 15 scans independently and blind to clinical data for: presence (versus absence) of any intracranial arterial abnormality (stenosis or occlusion), severity of arterial abnormality using relevant scales (IST-3 angiography score, Thrombolysis in Cerebral Infarction (TICI) score, Clot Burden Score), collateral supply and visibility of a perfusion defect on CTA source images (CTA-SI). Intra-observer reliability was assessed using independently repeated expert panel scan ratings. We assessed observer agreement with Krippendorff’s-alpha (K-alpha).

Results

Among experienced observers, inter-observer agreement was substantial for the identification of any angiographic abnormality (K-alpha = 0.70) and with an angiography assessment scale (K-alpha = 0.60–0.66). There was less agreement for grades of collateral supply (K-alpha = 0.56) or for identification of a perfusion defect on CTA-SI (K-alpha = 0.32). Radiology trainees performed as well as expert readers when additional training was undertaken (neuroradiology specialist trainees). Intra-observer agreement among experts provided similar results (K-alpha = 0.33–0.72).

Conclusion

For most imaging characteristics assessed, CTA has moderate to substantial observer agreement in acute ischaemic stroke. Experienced readers and those with specialist training perform best.

Electronic supplementary material

The online version of this article (doi:10.1007/s00234-014-1441-0) contains supplementary material, which is available to authorized users.

Acute blood pressure reduction in patients with intracerebral hemorrhage does not result in borderzone region hypoperfusion

BACKGROUND AND PURPOSE

The Intracerebral Hemorrhage Acutely Decreasing Arterial Pressure Trial (ICH ADAPT) demonstrated blood pressure (BP) reduction does not affect mean perihematoma or hemispheric cerebral blood flow. Nonetheless, portions of the perihematoma and borderzones may reach ischemic thresholds after BP reduction. We tested the hypothesis that BP reduction after intracerebral hemorrhage results in increased critically hypoperfused tissue volumes.

METHODS

Patients with Intracerebral hemorrhage were randomized to a target systolic BP (SBP) of <150 or <180 mm Hg and imaged with computed tomographic perfusion 2 hours later. The volumes of tissue below cerebral blood flow thresholds for ischemia (<18 mL/100 g/min) and infarction (<12 mL/100 g/min) were calculated as a percentage of the total volume within the internal and external borderzones and the perihematoma region.

RESULTS

Seventy-five patients with intracerebral hemorrhage were randomized a median (interquartile range) of 7.8 (13.3) hours from onset. Acute hematoma volume was 17.8 (27.1) mL and mean SBP was 183±22 mm Hg. At the time of computed tomographic perfusion (2.3 [1.0] hours after randomization), SBP was lower in the <150 mm Hg (n=37; 140±18 mm Hg) than in the <180 mm Hg group (n=36; 162±12 mm Hg; P<0.001). BP treatment did not affect the percentage of total borderzone tissue with cerebral blood flow<18 (14.7±13.6 versus 15.6±13.7%; P=0.78) or <12 mL/100 g/min (5.1±5.1 versus 5.8±6.8%; P=0.62). Similar results were found in the perihematoma region. Low SBP load (fraction of time with SBP<150 mmHg) did not predict borderzone tissue volume with cerebral blood flow<18 mL/100 g/min (β=0.023 [-0.073, 0.119]).

CONCLUSIONS

BP reduction does not increase the volume of critically hypoperfused borderzone or perihematoma tissue. These data support the safety of early BP reduction in intracerebral hemorrhage.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00963976.

Early reperfusion rates with IV tPA are determined by CTA clot characteristics

BACKGROUND AND PURPOSE

An ability to predict early reperfusion with IV tPA in patients with acute ischemic stroke and intracranial clots can help clinicians decide if additional intra-arterial therapy is needed or not. We explored the association between novel clot characteristics on baseline CTA and early reperfusion with IV tPA in patients with acute ischemic stroke by using classification and regression tree analysis.

MATERIALS AND METHODS

Data are from patients with acute ischemic stroke and proximal anterior circulation occlusions from the Calgary CTA data base (2003-2012) and the Keimyung Stroke Registry (2005-2009). Patients receiving IV tPA followed by intra-arterial therapy were included. Clot location, length, residual flow within the clot, ratio of contrast Hounsfield units pre- and postclot, and the M1 segment origin to the proximal clot interface distance were assessed on baseline CTA. Early reperfusion (TICI 2a and above) with IV tPA was assessed on the first angiogram.

RESULTS

Two hundred twenty-eight patients (50.4% men; median age, 69 years; median baseline NIHSS score, 17) fulfilled the inclusion criteria. Median symptom onset to IV tPA time was 120 minutes (interquartile range = 70 minutes); median IV tPA to first angiography time was 70.5 minutes (interquartile range = 62 minutes). Patients with residual flow within the clot were 5 times more likely to reperfuse than those without it. Patients with residual flow and a shorter clot length (≤15 mm) were most likely to reperfuse (70.6%). Patients with clots in the M1 MCA without residual flow reperfused more if clots were distal and had a clot interface ratio in Hounsfield units of <2 (36.8%). Patients with proximal M1 clots without residual flow reperfused 8% of the time. Carotid-T/-L occlusions rarely reperfused (1.7%). Interrater reliability for these clot characteristics was good.

CONCLUSIONS

Our study shows that clot characteristics on CTA help physicians estimate a range of early reperfusion rates with IV tPA.

Abstract 163: Hurry Acute Stroke Treatment and Evaluation (HASTE): Improving Door-to-Needle Times and Reducing Variation for Acute Ischemic Stroke using a Six-Sigma Approach

Background: The importance of immediate tissue-type plasminogen activator (tPA) therapy for acute ischemic strokes has long been recognized to achieve better outcomes. Clinical Best Practice Guidelines state that an acceptable treatment window for acute ischemic stroke patients is 4.5 hours from symptom onset. Within this time window, general consensus is the patient should arrive at the hospital within 3.5 hours of symptom onset, and the door-to-needle (DTN) time should be within 60 minutes of arrival. However, compliance with this DTN time is low with as few as 27% of acute stroke patients in the US being treated within 60 minutes.

Methods: The Calgary Stroke Program, a comprehensive stroke center at the Foothills Medical Centre, engaged in a six-sigma quality improvement project to improve DTN times. Six-sigma is a data-driven improvement approach with five phases: define the system and project goals; measure the process; analyze the data; improve the process; and control the improvements. The factors that led to improvement were: physician leadership; stroke team engagement with EMS, emergency department, admitting and diagnostic imaging; use of STAT! stroke pager to alert the stroke team when EMS or triage identified an eligible tPA patient; distribution of a weekly reports for DTN; and provision of a weekly award for the best case of the week under 30 minutes.

Results: The six-sigma approach resulted in a significant reduction in DTN. Data analysis was done for three periods: 1) the pre-implementation period (June 2011 to May 2013, n=300); 2) the implementation period (June 2013 to September 2013, n=46); and 3) the post implementation period (October 2013 to December 2013, n=39). The results showed a reduction in DTN from a median time of 53 minutes (mean=61 min) in the pre period to a median time of 51 minutes (mean=58 min) in the implementation period, and finally to a median time of 39 minutes (mean=46 minutes) in the post period. Based on six-sigma data analysis, the defects, defined by a DTN greater than 60 minutes, went down from 38 for every 100 patients (sigma level of 1.81) in the pre period to 26 for every 100 patients (sigma level of 2.15) in the post period. Furthermore, the results from a one-way ANOVA for the DTN times for these 3 periods reached statistical significance (p=0.013) with post-hoc analysis revealing that the difference between the pre and post periods results were significant.

Conclusions: The use of quality improvement approaches such as six-sigma can result in significant improvement in DTN. The data-driven approach of six-sigma allowed the Calgary Stroke Program to identify and improve various processes that effect the DTN time, which resulted in a lower average DTN time and a reduction in variation.

Diagnostic and Prognostic Impact of pc-ASPECTS Applied to Perfusion CT in the Basilar Artery International Cooperation Study

BACKGROUND AND PURPOSE

The posterior circulation Acute Stroke Prognosis Early CT Score (pc-APECTS) applied to CT angiography source images (CTA-SI) predicts the functional outcome of patients in the Basilar Artery International Cooperation Study (BASICS). We assessed the diagnostic and prognostic impact of pc-ASPECTS applied to perfusion CT (CTP) in the BASICS registry population.

METHODS

We applied pc-ASPECTS to CTA-SI and cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) parameter maps of BASICS patients with CTA and CTP studies performed. Hypoattenuation on CTA-SI, relative reduction in CBV or CBF, or relative increase in MTT were rated as abnormal.

RESULTS

CTA and CTP were available in 27/592 BASICS patients (4.6%). The proportion of patients with any perfusion abnormality was highest for MTT (93%; 95% confidence interval [CI], 76%-99%), compared with 78% (58%-91%) for CTA-SI and CBF, and 46% (27%-67%) for CBV (P < .001). All 3 patients with a CBV pc-ASPECTS < 8 compared to 6/23 patients with a CBV pc-ASPECTS ≥ 8 had died at 1 month (RR 3.8; 95% CI, 1.9-7.6).

CONCLUSION

CTP was performed in a minority of the BASICS registry population. Perfusion disturbances in the posterior circulation were most pronounced on MTT parameter maps. CBV pc-ASPECTS < 8 may indicate patients with high case fatality.

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.

Evaluation of interval times from onset to reperfusion in patients undergoing endovascular therapy in the Interventional Management of Stroke III trial

BACKGROUND

Meaningful delays occurred in the Interventional Management of Stroke (IMS) III trial. Analysis of the work flow will identify factors contributing to the in-hospital delays.

METHODS AND RESULTS

In the endovascular arm of the IMS III trial, the following time intervals were calculated: stroke onset to emergency department arrival; emergency department to computed tomography (CT); CT to intravenous tissue plasminogen activator start; intravenous tissue plasminogen activator start to randomization; randomization to groin puncture; groin puncture to thrombus identification; thrombus identification to start of endovascular therapy; and start of endovascular therapy to reperfusion. The effects of enrollment time, CT angiography use, interhospital transfers, and intubation on work flow were evaluated. Delays occurred notably in the time intervals from intravenous tissue plasminogen activator initiation to groin puncture (median 84 minutes) and start of endovascular therapy to reperfusion (median 85 minutes). The CT to groin puncture time was significantly shorter during working hours than after. Times from emergency department to reperfusion and groin puncture to reperfusion decreased over the trial period. Patients with CT angiography had shorter emergency department to reperfusion and onset to reperfusion times. Transfer of patients resulted in a longer onset to reperfusion time compared with those treated in the same center. Age, sex, National Institutes of Health Stroke Scale score, and intubation did not affect delays.

CONCLUSIONS

Important delays were identified before reperfusion in the IMS III trial. Delays decreased as the trial progressed. Use of CT angiography and endovascular treatment in the same center were associated with time savings. These data may help in optimizing work flow in current and future endovascular trials.

CLINICAL TRIAL REGISTRATION URL

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

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.

Does the sex of acute stroke patients influence the effectiveness of rt-PA?

BACKGROUND

Women have been reported to show more frequent recanalization and better recovery after intravenous (IV) recombinant tissue plasminogen activator (rt-PA) treatment for acute stroke compared with men. To investigate this we studied a series of stroke patients receiving IV rt-PA and undergoing acute transcranial doppler (TCD) examination.

METHODS

Acute stroke patients received IV rt-PA and had acute TCD examination within 4 hours of symptom onset at 4 major stroke centers. TCD findings were interpreted using the Thrombolysis in Brain Ischemia (TIBI) flow grading system. The recanalization rates, and poor 3-month outcomes (modified Rankin scale >2) of men and women were compared using the chi-square test. Multiple regression analysis was used to assess sex as a predictor of recanalization and poor 3-month outcome after controlling for age, baseline NIH Stroke Scale (NIHSS), time to treatment, hypertension, and blood glucose.

RESULTS

369 patients had TCD examinations before or during IV rt-PA treatment. The 199 (53.9%) men and 170 (46.1%) women had mean ages of 67 ± 13 and 70 ± 14 years, respectively. The sexes did not differ significantly in baseline stroke severity, time to TCD examination, or time to thrombolysis. Of the men, 68 (34.2%) had complete recanalization, 58 (29.1%) had partial recanalization, and 73 (36.6%) had no recanalization. Of the women, 53 (31.2%) had complete recanalization, 46 (27%) had partial recanalization, and 71 (41.8%) had no recanalization (p = 0.6). Multiple regression analyses showed no difference between the sexes in recanalization rate, time to recanalization, or clinical outcome at 3 months.

CONCLUSIONS

In our study; sex is not a significant predictor of recanalization rate, time to recanalization or 3-month outcome in stroke patients following IV rt-PA.

TRIAL REGISTRATION

Data from CLOTBUST trial Clinicaltrials.gov Identifier: NCT01240356.

Not all "successful" angiographic reperfusion patients are an equal validation of a modified TICI scoring system

Rapid reperfusion of the entire territory distal to vascular occlusions is the aim of stroke interventions. Recent studies defined successful reperfusion as establishing some perfusion with distal branch filling of <50% of territory visualized (Thrombolysis In Cerebral Infarction "TICI" 2a) or more. We investigate the importance of the quality of final reperfusion and whether a revision of the successful reperfusion definition is warranted. We retrospectively evaluated a prospective database of anterior circulation strokes treated using stentrievers to assess the quality of final reperfusion using two scores: the traditional TICI score and a modified TICI score. The modified TICI score includes an additional category (TICI 2c): near complete perfusion except for slow flow or distal emboli in a few distal cortical vessels. We compared different cut-off definitions of reperfusion (TICI 2a - 3 vs. TICI-2b-3 vs. TICI 2c-3) using the area under the curve to identify their correlation with a favorable 90-day outcome (mRS≤2). In our cohort of 110 patients, 90% achieved TICI 2a-3 reperfusion with 80% achieving TICI 2b-3 and 55.5% achieving TICI 2c-3. The proportion of patients with a favorable 90-day outcome was higher in the TICI 2c (62.5%) compared to TICI 2b (44.4%) or TICI 2a (45.5%) but similar to the TICI 3 group (75.9%). A TICI 2c-3 reperfusion had a better predictive value than TICI 2b-3 for 90-day mRS 0-1. Defining successful reperfusion as TICI 2c/3 has merits. In this cohort, there was evidence toward faster recovery and better outcomes in patients with the TICI 2c vs. the traditional TICI 2b grade.