Global stroke statistics 2023: Availability of reperfusion services around the world

BACKGROUND

Disparities in the availability of reperfusion services for acute ischemic stroke are considerable globally and require urgent attention. Contemporary data on the availability of reperfusion services in different countries are used to provide the necessary evidence to prioritize where access to acute stroke treatment is needed.

AIMS

To provide a snapshot of published literature on the provision of reperfusion services globally, including when facilitated by telemedicine or mobile stroke unit services.

METHODS

We searched PubMed to identify original articles, published up to January 2023 for the most recent, representative, and relevant patient-level data for each country. Keywords included thrombolysis, endovascular thrombectomy and telemedicine. We also screened reference lists of review articles, citation history of articles, and the gray literature. The information is provided as a narrative summary.

RESULTS

Of 11,222 potentially eligible articles retrieved, 148 were included for review following de-duplications and full-text review. Data were also obtained from national stroke clinical registry reports, Registry of Stroke Care Quality (RES-Q) and PRE-hospital Stroke Treatment Organization (PRESTO) repositories, and other national sources. Overall, we found evidence of the provision of intravenous thrombolysis services in 70 countries (63% high-income countries (HICs)) and endovascular thrombectomy services in 33 countries (68% HICs), corresponding to far less than half of the countries in the world. Recent data (from 2019 or later) were lacking for 35 of 67 countries with known year of data (52%). We found published data on 74 different stroke telemedicine programs (93% in HICs) and 14 active mobile stroke unit pre-hospital ambulance services (80% in HICs) around the world.

CONCLUSION

Despite remarkable advancements in reperfusion therapies for stroke, it is evident from available patient-level data that their availability remains unevenly distributed globally. Contemporary published data on availability of reperfusion services remain scarce, even in HICs, thereby making it difficult to reliably ascertain current gaps in the provision of this vital acute stroke treatment around the world.

Intracranial Large Artery Disease is Independently Associated with Poor Functional Outcome in a Cohort of Ethnic South Asian Ischemic Stroke Patients

Background

Intracranial large artery disease (ICLAD) in ischemic stroke patients is associated with an increased risk for recurrent stroke; however, it is not known if ICLAD influences functional status following stroke. We studied the 6-month functional outcome in south Asian ischemic stroke patients and compared those with and without ICLAD.

Materials and Methods

This is a prospective cohort study of consecutive south Asian ischemic stroke patients. ICLAD was assessed with transcranial color-coded Doppler ultrasound or magnetic resonance angiography. Functional outcomes were obtained via telephone interviews with poor outcome defined as modified Rankin scale of 3-6.

Results

Of 216 ischemic stroke patients studied, 203 (93.9%) had follow-up data, of whom 50.7% (103) had ICLAD. Patients with ICLAD had a higher prevalence of hypertension (P < 0.001), hyperlipidemia (P = 0.047), ischemic heart disease (P = 0.030), and extracranial carotid disease (P = 0.005). A higher proportion of patients with ICLAD had poor functional outcome at 6 months (30.1%) versus those without ICLAD (13.0%) (P = 0.004). After adjusting for age, sex, hypertension, hyperlipidemia, diabetes, ischemic heart disease, atrial fibrillation, extracranial carotid stenosis, and recurrent vascular events, patients with ICLAD were 3.01 (95% confidence interval: 1.35-7.10) times more likely than those without ICLAD to have poor functional outcome.

Conclusions

The presence of ICLAD rendered poorer functional prognosis after stroke. These findings support the specific evaluation of the benefits of known acute stroke treatments such as thrombolysis, as well as investigation of potential novel strategies such as acute stenting.

Stroke Rehabilitation Use and Caregiver Psychosocial Health Profiles in Singapore: A Latent Profile Transition Analysis

OBJECTIVES

To identify and describe caregiver profiles based on their psychosocial health characteristics over a 12-month period and transitions among these profiles, to determine if stroke rehabilitation use at 12 months post-stroke differed by caregiver profile transition patterns, and to investigate if caregiver profiles at 3 months post-stroke moderate the association of stroke rehabilitation use at 3 months and 12 months post-stroke after accounting for covariates.

DESIGN

Latent profile transition analysis of caregiver psychosocial health with stroke rehabilitation use at 12 month post-stroke as outcome.

SETTING AND PARTICIPANTS

A total of 149 stroke patient-caregiver dyads from the Singapore Stroke Study.

METHODS

Cross-sectional latent profile analyses were conducted on caregiver psychosocial health indicators of burden, depression, health status, quality of relationship with patient, and social support. Changes in latent profile classification over 3 time points (baseline, 3 months, and 12 months post-stroke) were analyzed using latent transition analysis. A transition model with stroke rehabilitation use at 12 months post-stroke as the outcome was tested after accounting for covariates.

RESULTS

Two distinct caregiver psychosocial health latent profiles were found across time: nondistressed and distressed. Most caregivers were classified as nondistressed and remained nondistressed over time. Distressed caregivers at baseline were 76% likely to become nondistressed at 12 month post-stroke. Regardless of profile transition patterns, nondistressed caregivers at 12 months post-stroke tended to have cared for stroke rehabilitation nonusers at 12 months post-stroke. Patient depression explained profile classification at 3 months and 12 months post-stroke. After accounting for covariates, rehabilitation users at 3 months post-stroke tended to continue using rehabilitation at 12 months post-stroke only when they had nondistressed caregivers at 3 months post-stroke.

CONCLUSIONS AND IMPLICATIONS

Whether caregiver adaptation explains the associations between the latent profile transition patterns and rehabilitation use at 12 months post-stroke should be examined. Early psychosocial health assessment and sustained support should be made available to stroke caregivers to enhance their well-being and subsequent patient rehabilitation participation.

Stroke Patients Without COVID-19 Symptoms: Is There a Need to Screen?

INTRODUCTION

COVID-19 patients who present with strokes but without typical COVID-19 symptoms have been described in small numbers. Despite the paucity of fever and respiratory symptoms, they remain capable of infecting others. The patient we discuss herein highlights the important issues of strokes as presenting events of COVID-19 infections, and how testing for COVID-19 in stroke patients, even when asymptomatic for COVID-19, can play an important role in infection control, clinical management and outcomes amidst this global pandemic.

CASE REPORT

A 45-year-old male resident of a dormitory presented to our unit with acute vertigo and left-sided dysmetria. NIHSS was 2. The initial magnetic resonance imaging demonstrated infarction of the left cerebellar hemisphere, middle cerebellar peduncle and hemipons. An extensive work-up for stroke etiologies was unremarkable. Despite having no fever, respiratory symptoms, anosmia or ageusia, he was isolated and screened for COVID-19 due to his epidemiologic risks, with multiple residents from his dormitory being recently diagnosed with COVID-19. Confirming our suspicion, his respiratory samples returned positive for COVID-19. His D-dimer levels returned normal. Thereafter, the patient underwent posterior decompression surgery due to worsening edema caused by the cerebellar infarct. He was started on antiplatelet therapy and recovered significantly a month from presentation with an modified Rankin Sore of 2. He remained without typical COVID-19 symptoms.

CONCLUSION

Our patient's case clearly supports the screening for COVID-19 in stroke patients who are without COVID-19 symptoms, appreciating the significant value it adds to infection control, clinical management, and outcomes amidst this global pandemic.

Abstract P227: Incentives for Uptake and Adherence With Outpatient Stroke Rehabilitation: A Three Arm Randomized Controlled Trial

Introduction: While rehabilitation has been demonstrated to be effective in improving outcomes of stroke, uptake of outpatient rehabilitation services (ORS) in Singapore remains relatively low. This study aims to determine if rehabilitation uptake and adherence can be increased by providing coordinated transportation (increased convenience) and eliminating out-of-pocket costs (reduced expense).

Hypothesis: It was hypothesized that the uptake rate of ORS over 3 months, number of sessions attended, and time to discontinuation would be greater for participants in the intervention arms of which barriers of transportation and out-of-pocket costs are addressed, as compared to participants in the control arm.

Methods: A total of 266 participants were recruited from the stroke and acute rehabilitation units of two tertiary hospitals in Singapore, and randomized to one of three study arms: the control arm, denoted Education ( E ), inclusive of a stroke rehabilitation educational program; the first intervention arm, denoted Transportation Incentives ( T ), inclusive of free transportation services for the first 3 months post-discharge; or the second intervention arm, denoted, Transportation & Sessions Incentives ( T&S ), inclusive of up to 3 months of both free transportation and no out-of-pocket costs for participants’ stroke ORS.

Results: The uptake rate of ORS was 73.0% for E (CI, 63.8%-82.3%), 81.8% for T (CI, 73.8%-89.8%), and 84.3% for T&S (CI, 76.7%-91.8%). The differences of T and T&S versus the control arm ( E ) were not statistically significant (p = 0.22 and p = 0.10, respectively). However, the average number of rehabilitation sessions attended were significantly higher in both the intervention arms: 5.50 (SD, 7.65) for T and 7.51 (SD, 9.52) for T&S versus 3.26 (SD, 4.22) for the control arm ( E ) (p-value for T vs E = 0.017; p-value for T&S vs E = 0.000.) Kaplan-Meier analysis indicated that persistence was higher for T&S compared to E (p=0.029).

Conclusions: This study has demonstrated that incentives can improve utilization of ORS. Such incentives should be considered in finance policy, such as care bundling, for stroke or similar common conditions.

Association of Reperfusion After Thrombolysis With Clinical Outcome Across the 4.5- to 9-Hours and Wake-up Stroke Time Window: A Meta-Analysis of the EXTEND and EPITHET Randomized Clinical Trials

Importance

Intravenous alteplase reduces disability after ischemic stroke in patients 4.5 to 9 hours after onset and with wake-up onset stroke selected using perfusion imaging mismatch. However, whether the benefit is consistent across the 4.5- to 6-hours, 6- to 9-hours, and wake-up stroke epochs is uncertain.

Objective

To examine the association of reperfusion with reduced disability, including by onset-to-randomization time strata in the Extending the Time for Thrombolysis in Emergency Neurological Deficits (EXTEND) and Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET) randomized clinical trials.

Design, Setting, and Participants

Individual patient meta-analysis of randomized clinical trials performed from August 2001 to June 2018 with 3-month follow-up. Patients had acute ischemic stroke with 4.5-to 9-hours poststroke onset or with wake-up stroke were randomized to alteplase or placebo after perfusion mismatch imaging. Analysis began July 2019 and ended May 2020.

Exposures

Reperfusion was defined as more than 90% reduction in time to maximum of more than 6 seconds' lesion volume at 24- to 72-hour follow-up.

Main Outcomes and Measures

Ordinal logistic regression adjusted for baseline age and National Institutes of Health Stroke Scale score was used to analyze functional improvement in day 90 modified Rankin Scale score overall, including a reperfusion × time-to-randomization multiplicative interaction term, and in the 4.5- to 6-hours, 6- to 9-hours, and wake-up time strata. Symptomatic hemorrhage was defined as large parenchymal hematoma with a National Institutes of Health Stroke Scale score increase of 4 points or more.

Results

Reperfusion was assessable in 270 of 295 patients (92%), 68 of 133 (51%) in the alteplase group, and 38 of 137 (28%) in the placebo reperfused group (P < .001). The median (interquartile range) age was 76 (66-81) years in the reperfusion group vs 74 (64.5-81.0) years in the group with no reperfusion. The median (interquartile range) baseline National Institutes of Health Stroke Scale score was 10 (7-15) in the reperfusion group vs 12 (8.0-17.5) in the no reperfusion group. Overall, reperfusion was associated with improved functional outcome (common odds ratio, 7.7; 95% CI, 4.6-12.8; P < .001). Reperfusion was associated with significantly improved functional outcome in each of the 4.5- to 6-hours, 6- to 9-hours, and wake-up time strata, with no evidence of association between time to randomization and beneficial effect of reperfusion (P = .63). Symptomatic hemorrhage, assessed in all 294 patients, occurred in 3 of 51 (5.9%) in the 4.5- to 6-hours group, 2 of 28 (7.1%) in the 6- to 9-hours group, and 4 of 73 (5.5%) in the wake-up stroke in patients treated with alteplase (Fisher P = .91).

Conclusions and Relevance

Strong benefits of reperfusion in all time strata without differential risk in symptomatic hemorrhage support the consistent treatment effect of alteplase in perfusion mismatch-selected patients throughout the 4.5- to 9-hours and wake-up stroke time window.

Abstract 100: Reperfusion Improves Clinical Outcome Across the 4.5-9h and Wake-Up Stroke Time Continuum in EXTEND and EPITHET

Introduction: Intravenous alteplase reduces disability after ischemic stroke in patients 4.5-9h after onset and with wake-up onset stroke who have favorable perfusion imaging. We examined the benefit of reperfusion in reducing disability, including by onset to randomization time strata in the EXTEND and EPITHET randomized trials.

Methods: Patients were randomized to alteplase or placebo after perfusion mismatch imaging. Reperfusion was defined as >90% reduction in Tmax>6s lesion volume at 24h. Ordinal logistic regression adjusted for baseline age and NIHSS was used to analyze functional improvement in day 90 modified Rankin scale overall, including a reperfusion*time to randomization interaction term, and in the 4.5-6h, 6-9h and wake-up time strata. Symptomatic hemorrhage was defined as large parenchymal hematoma with ≥4 point NIHSS increase (SITS).

Results: Reperfusion was assessable in 270/294 (92%) patients, 68/133 (51%) alteplase and 38/137 (28%) placebo reperfused (p<0.001). Median age 76 (IQR 66-81) in reperfused vs 74 (IQR 64.5-81) in non-reperfused, median baseline NIHSS 10 (IQR 7-15) in reperfused vs 12 (IQR 8-17.5) in non-reperfused. Overall, reperfusion was associated with common odds ratio 7.7 (95%CI 4.6-12.8, p<0.0001) in ordinal “shift” analysis. There was no heterogeneity in the beneficial effect of reperfusion effect by time to randomization (p=0.63). Reperfusion was associated with significantly improved functional outcome in each of the 4.5-6h, 6-9h and wake-up time strata (figure). Symptomatic hemorrhage, assessed in all 294 patients, occurred in 3/51 (5.9%) 4.5-6h, 2/28 (7.1%) 6-9h, 4/73 (5.5%) wake-up stroke in the alteplase-treated patients (van Elteren p=0.66).

Conclusions: Strong benefits of reperfusion in all time strata without differential risk in symptomatic hemorrhage support the durable treatment effect of alteplase in perfusion mismatch-selected patients throughout the 4.5-9h and wake-up stroke time window.

Ischaemic stroke

Stroke is the second highest cause of death globally and a leading cause of disability, with an increasing incidence in developing countries. Ischaemic stroke caused by arterial occlusion is responsible for the majority of strokes. Management focuses on rapid reperfusion with intravenous thrombolysis and endovascular thrombectomy, which both reduce disability but are time-critical. Accordingly, improving the system of care to reduce treatment delays is key to maximizing the benefits of reperfusion therapies. Intravenous thrombolysis reduces disability when administered within 4.5 h of the onset of stroke. Thrombolysis also benefits selected patients with evidence from perfusion imaging of salvageable brain tissue for up to 9 h and in patients who awake with stroke symptoms. Endovascular thrombectomy reduces disability in a broad group of patients with large vessel occlusion when performed within 6 h of stroke onset and in patients selected by perfusion imaging up to 24 h following stroke onset. Secondary prevention of ischaemic stroke shares many common elements with cardiovascular risk management in other fields, including blood pressure control, cholesterol management and antithrombotic medications. Other preventative interventions are tailored to the mechanism of stroke, such as anticoagulation for atrial fibrillation and carotid endarterectomy for severe symptomatic carotid artery stenosis.

Home-based tele-rehabilitation presents comparable positive impact on self-reported functional outcomes as usual care: The Singapore Tele-technology Aided Rehabilitation in Stroke (STARS) randomised controlled trial

INTRODUCTION

The aim of this research was to evaluate the impact of a novel tele-rehabilitation system on self-reported functional outcomes compared to usual care during the first three months after stroke.

METHODS

A parallel, two-arm, evaluator-blinded, randomised controlled trial was conducted. Adults aged ≥40 years who had suffered a stroke within four weeks of the start of the study were recruited from the general community. The intervention group received access to a novel tele-rehabilitation system and programme for three months. The primary outcome measures utilised were the frequency and limitation total scores of the Late-Life Function and Disability Instrument (LLFDI) at three months.

RESULTS

A total of 124 individuals were recruited. The mean differences in the LLDFI frequency and limitation total scores at three months comparing the intervention and control groups were -3.30 (95% confidence interval (CI) -7.81 to 1.21) and -6.90 (95% CI -15.02 to 1.22), respectively. Adjusting for the respective baseline covariates and baseline Barthel Index also showed no significant difference between interventions in the LLFDI outcomes.

DISCUSSION

The intervention and control groups self-reported similar improvements in functional outcomes. Tele-rehabilitation may be a viable option to provide post-stroke rehabilitation services in Singapore while reducing barriers to continue rehabilitation conventionally after discharge from hospital and encouraging more participation.

Extending thrombolysis to 4·5-9 h and wake-up stroke using perfusion imaging: a systematic review and meta-analysis of individual patient data

BACKGROUND

Stroke thrombolysis with alteplase is currently recommended 0-4·5 h after stroke onset. We aimed to determine whether perfusion imaging can identify patients with salvageable brain tissue with symptoms 4·5 h or more from stroke onset or with symptoms on waking who might benefit from thrombolysis.

METHODS

In this systematic review and meta-analysis of individual patient data, we searched PubMed for randomised trials published in English between Jan 1, 2006, and March 1, 2019. We also reviewed the reference list of a previous systematic review of thrombolysis and searched ClinicalTrials.gov for interventional studies of ischaemic stroke. Studies of alteplase versus placebo in patients (aged ≥18 years) with ischaemic stroke treated more than 4·5 h after onset, or with wake-up stroke, who were imaged with perfusion-diffusion MRI or CT perfusion were eligible for inclusion. The primary outcome was excellent functional outcome (modified Rankin Scale [mRS] score 0-1) at 3 months, adjusted for baseline age and clinical severity. Safety outcomes were death and symptomatic intracerebral haemorrhage. We calculated odds ratios, adjusted for baseline age and National Institutes of Health Stroke Scale score, using mixed-effects logistic regression models. This study is registered with PROSPERO, number CRD42019128036.

FINDINGS

We identified three trials that met eligibility criteria: EXTEND, ECASS4-EXTEND, and EPITHET. Of the 414 patients included in the three trials, 213 (51%) were assigned to receive alteplase and 201 (49%) were assigned to receive placebo. Overall, 211 patients in the alteplase group and 199 patients in the placebo group had mRS assessment data at 3 months and thus were included in the analysis of the primary outcome. 76 (36%) of 211 patients in the alteplase group and 58 (29%) of 199 patients in the placebo group had achieved excellent functional outcome at 3 months (adjusted odds ratio [OR] 1·86, 95% CI 1·15-2·99, p=0·011). Symptomatic intracerebral haemorrhage was more common in the alteplase group than the placebo group (ten [5%] of 213 patients vs one [<1%] of 201 patients in the placebo group; adjusted OR 9·7, 95% CI 1·23-76·55, p=0·031). 29 (14%) of 213 patients in the alteplase group and 18 (9%) of 201 patients in the placebo group died (adjusted OR 1·55, 0·81-2·96, p=0·66).

INTERPRETATION

Patients with ischaemic stroke 4·5-9 h from stroke onset or wake-up stroke with salvageable brain tissue who were treated with alteplase achieved better functional outcomes than did patients given placebo. The rate of symptomatic intracerebral haemorrhage was higher with alteplase, but this increase did not negate the overall net benefit of thrombolysis.

FUNDING

None.

Health-related quality of life loss associated with first-time stroke

OBJECTIVES

This study aimed to quantify health-related quality of life (HRQoL) loss associated with first episode of stroke by comparing patient-reported HRQoL before and after stroke onset. The impact of stroke in local population was also evaluated by comparing the pre- and post-stroke HRQoL with that of the general population.

METHODS

The HRQoL of stroke survivors was assessed with the EQ-5D-3L index score at recruitment, for recalled pre-stroke HRQoL, and at 3 and 12 month post-stroke. Change in HRQoL from pre-stroke to 3 and 12 month was self-reported by 285 and 238 patients, respectively. Mean EQ index score at each time point (baseline: 464 patients; 3 month post-stroke: 306 patients; 12 month post-stroke: 258 patients) was compared with published population norms for EQ-5D-3L.

RESULTS

There was a significant decrease in HRQoL at 3 (0.25) and 12 month (0.09) post-stroke when compared to the retrospectively recalled patients' mean pre-stroke HRQoL level (0.87). The reduction at 3 month was associated with the reduction in all EQ-5D-3L health dimensions; reductions remaining at 12 month were limited to dimensions of mobility, self-care, usual activities, and anxiety/depression. Stroke patients had a lower mean EQ index than the general population by 0.07 points pre-stroke (0.87 vs. 0.94), 0.33 points at 3 month (0.61 vs. 0.94) and 0.18 points at 12 month (0.76 vs. 0.94) post-stroke.

CONCLUSIONS

Stroke has a substantial impact on HRQoL in Singapore, especially in the first three months post-stroke. Compared to the general population, stroke survivors have lower HRQoL even before stroke onset. This pre-stroke deficit in HRQoL should be taken into account when quantifying health burden of stroke or setting goals for stroke rehabilitation.

Can acute clinical outcomes predict health-related quality of life after stroke: a one-year prospective study of stroke survivors

BACKGROUND

Health-related quality of life (HRQoL) is a key metric to understand the impact of stroke from patients' perspective. Yet HRQoL is not readily measured in clinical practice. This study aims to investigate the extent to which clinical outcomes during admission predict HRQoL at 3 months and 1 year post-stroke.

METHODS

Stroke patients admitted to five tertiary hospitals in Singapore were assessed with Shah-modified Barthel Index (Shah-mBI), National Institute of Health Stroke Scale (NIHSS), Modified Rankin Scale (mRS), Mini-Mental State Examination (MMSE), and Frontal Assessment Battery (FAB) before discharge, and the EQ-5D questionnaire at 3 months and 12 months post-stroke. Association of clinical measures with the EQ index at both time points was examined using multiple linear regression models. Forward stepwise selection was applied and consistently significant clinical measures were analyzed for their association with individual dimensions of EQ-5D in multiple logistic regressions.

RESULTS

All five clinical measures at baseline were significant predictors of the EQ index at 3 months and 12 months, except that MMSE was not significantly associated with the EQ index at 12 months. NIHSS (3-month standardized β = - 0.111; 12-month standardized β = - 0.109) and mRS (3-month standardized β = - 0.122; 12-month standardized β = - 0.080) were shown to have a larger effect size than other measures. The contribution of NIHSS and mRS as significant predictors of HRQoL was mostly explained by their association with the mobility, self-care, and usual activities dimensions of EQ-5D.

CONCLUSIONS

HRQoL at 3 months and 12 months post-stroke can be predicted by clinical outcomes in the acute phase. NIHSS and mRS are better predictors than BI, MMSE, and FAB.

The Relationship Between Ambient Air Pollution and Acute Ischemic Stroke: A Time-Stratified Case-Crossover Study in a City-State With Seasonal Exposure to the Southeast Asian Haze Problem

STUDY OBJECTIVE

Studies are divided on the short-term association of air pollution with stroke. Singapore is exposed to seasonal transboundary haze. We aim to investigate the association between air pollution and stroke incidence in Singapore.

METHODS

We performed a time-stratified case-crossover analysis on all ischemic stroke cases reported to the Singapore Stroke Registry from 2010 to 2015. Exposure on days was compared with control days on which exposure did not occur. Control days were chosen on the same day of the week earlier and later in the same month in the same year. We fitted a conditional Poisson regression model to daily stroke incidence that included Pollutant Standards Index and environmental confounders. The index was categorized according to established classification (0 to 50=good, 51 to 100=moderate, and ≥101=unhealthy). We assessed the relationship between stroke incidence and Pollutant Standards Index in the entire cohort and in predetermined subgroups of individual-level characteristics.

RESULTS

There were 29,384 ischemic stroke cases. Moderate and unhealthy Pollutant Standards Index levels showed association with stroke occurrence, with incidence risk ratio 1.10 (95% confidence interval 1.06 to 1.13) and 1.14 (95% confidence interval 1.03 to 1.25), respectively. Subgroup analyses showed generally significant association, except in Indians and nonhypertensive patients. The association was significant in subgroups aged 65 years or older, women, Chinese, nonsmokers and those with history of diabetes, hypertension, and hyperlipidemia. Stratified by age and smoking, the risk diminished in smokers of all ages. Risk remained elevated for 5 days after exposure.

CONCLUSION

We found a short-term elevated risk of ischemic stroke after exposure to air pollution. These findings have public health implications for stroke prevention and emergency health services delivery.

Abstract WP155: Diabetes Predicts for Poor Long-term Functional Outcome After Acute Ischemic Stroke

Background: Stroke and diabetes are important causes of disability. The impact of diabetes on long-term functional outcomes after stroke is unclear. Our primary aim was to compare functional outcomes periodically over 7 years between diabetic and non-diabetic ischemic stroke patients. We also investigated the impact of diabetes on the long-term trajectory of functional outcomes, and the influence of age on the diabetes-functional outcome association.

Methods: This is a longitudinal observational cohort study of 802 acute ischemic stroke patients recruited from a tertiary hospital in Singapore from 2005 to 2007. Functional outcomes were assessed using the modified Rankin Scale (mRS) with poor functional outcome defined as mRS ≥ 3. Follow-up data was determined at 6 months, a median of 29 months and 86 months.

Results: Among the 802 ischemic stroke patients studied, 45% were > 65 years old and 42% had diabetes. Diabetic patients were more likely to have poor functional outcomes at 6 months (OR = 2.122, 95% CI: 1.226-3.673), and at median follow-up durations of 29 months (OR = 1.957, 95% CI: 1.366-2.814) and 86 months (OR = 2.269, 95% CI: 1.583-3.253), after adjustment of covariates. Diabetes was not an interaction factor for both mRS distribution and poor functional outcome when comparing between the various follow-up time-points. There was a significant interaction between age and diabetic status in terms of poor functional outcome in the long-term.

Conclusion: Diabetes is a prognostic factor for poor functional outcomes after ischemic stroke; its impact remained consistent throughout the 7-year follow-up period and was influenced by age in the long-term.

Abstract TP415: A Pilot Study on the Effect of Neck Irradiation Treatment for Nasopharyngeal Carcinoma on Carotid Artery Stenosis

Introduction: Extracranial carotid stenosis, a risk factor for ischemic stroke, is thought to be accelerated by irradiation to the neck region. Nasopharyngeal carcinoma (NPC) has a predilection for East Asian with an incidence of 200-300 annually in Singapore. We studied the prevalence and severity of extracranial carotid disease in patients with prior neck irradiation for NPC, who were at different timepoints from the time of irradiation.

Hypothesis: The prevalence of extracranial carotid disease is high among patients with prior neck irradiation, and this may justify a screening programme for early detection and primary stroke prevention.

Methods: We conducted a pilot study to examine 50 patients (median age 55.2 years) with prior radiation for NPC with intensity-modulated radiation therapy (IMRT): 26 with <5 years after treatment and 24 with >=5 years after treatment. All patients received radiation therapy to the neck. Carotid disease was assessed by duplex sonography for severity of stenosis. The European Carotid Surgery Trial (ECST) criteria was employed for assessment for degree of stenosis.

Results: Among patients with IMRT >=5 years ago, 25% (6/24) had carotid stenosis of >=50% compared to only 8% (2/26) of patients with IMRT within 5 years. Of these 8 patients with carotid stenosis >=50%, 5 (63%) had plaques with irregular or ulcerated surfaces, which is known to be associated with stroke risk. Based on these preliminary data, the study would require a larger sample size of 100 in each group to be powered at 90% with an alpha of 0.05. All 8 patients with carotid stenosis >=50% from the screening were referred for further evaluation for symptoms and risk factors, and management for secondary stroke prevention.

Conclusions: Based on our findings, there is a rationale for screening for carotid disease among patients with prior neck irradiation and the timing of screening is more optimal after 5 years from IMRT. Patients found to have carotid disease should be counselled about risk factor control, antiplatelet medication and possibly carotid intervention for primary stroke prevention.

Two decades of nation-wide community-based stroke support - The Singapore National Stroke Association

The Singapore National Stroke Association, registered in 1996, offers support and information to stroke survivors and caregivers, and aims to raise public stroke awareness. In the last 20 years, we have developed programs to equip stroke survivors and caregivers with knowledge, life skills, comfort, and opportunities for socialization and reintegration. We have on-going public education and advocacy initiatives. Obtaining funding, member recruitment, volunteer retention, and leadership renewal are on-going challenges. Singapore National Stroke Association will continue to strive for the betterment of stroke survivors, their caregivers, and the public.

Abstract TP334: The Cultural Appropriateness of the National Institute of Health Stroke Scale (NIHSS) in Singapore: a Survey on Healthcare Workers’ Opinions

Introduction: The National Institute of Health Stroke Scale (NIHSS) is the most utilized scale for neurological deficits of stroke, assessing various components including dysphasia and dysarthria. However, some non-Western countries have found certain components in the NIHSS to be inappropriate due to cultural differences, but no studies have been conducted in Singapore. We sought the opinions of healthcare workers in Singapore who are involved in stroke care on the cultural appropriateness of the NIHSS.

Hypothesis: The NIHSS contains components which are considered culturally inappropriate by healthcare workers in Singapore.

Methods: We surveyed 79 healthcare workers who care for stroke patients (24 doctors, 40 nurses, 15 speech therapists), on cultural appropriateness of the dysphasia and dysarthria components of the NIHSS in Singapore, using a standardized questionnaire.

Results: The majority of respondents (84%) found ≥1 objects tested for dysphasia culturally inappropriate, with 33% substituting with another picture, 29% skipping the object and 32% using a physical object. Most (86%) opined that ≥1 dysphasia objects should be changed, specifically the hammock (67%) and cactus (51%). The dysphasia phrases and kitchen scene were reported as culturally inappropriate by 49% and 29% of the respondents respectively. For the dysarthria component, 58% found ≥1 word culturally inappropriate and 75% reported adjusting the acceptability of responses by patient demographics.

Conclusions: The dysphasia objects, dysphasia phrases and dysarthria phrases of the NIHSS are culturally inappropriate in Singapore. There are inconsistencies in handling these issues and responses are commonly being adjusted to patient’s demographics. Thus we aim to modify the standard NIHSS based on response to this survey and to develop a NIHSS version that is culturally suitable in Singapore.

Abstract TP139: Extracranial Carotid Occlusion: Incidence and Recanalisation Rates

Introduction: Internal carotid artery (ICA) occlusion can be found in up to 15% of patients with transient ischemic attacks and strokes. Common causes include cardiac sources, like Atrial Fibrillation (AF) or large vessel atherosclerosis. Spontaneous recanalization of an occluded ICA has been infrequently described, and most commonly occurs within a short period after the diagnosis of the presumed acute occlusion. The underlying disease will direct treatment plans of such patients. We aim to study spontaneous recanalization rates, and the clinical and sonographic features that may affect their recanalization rates.

Hypothesis: Acute carotid occlusion by embolic thrombus is more likely to recanalize than that due to underlying ruptured plaque.

Methods: A 5.5-year retrospective review of Singapore General Hospital Neurovascular Laboratory database from 2010, identifying all patients with acute symptomatic Extracranial Carotid Occlusion. The clinical and sonographic features were also collected.

Results: We identified 178 (2.5%) patients with symptomatic ICA occlusion out of 7229 patients (mean age 64 years, 69% males, 74% Chinese). 88% of them had hyperlipidemia, 74% hypertension, 45% diabetes mellitus, 39% smokers, 28% ischemic heart disease, 16% previous stroke, 15% AF and 7% prior neck irradiation. Most (97%) had unilateral carotid occlusions. Underlying calcified plaques were found in 37% of patients while 63% had homogenous, echoic to anechoic lesions (of which 25% were also mobile). Sixteen of 81(20%) patients had recanalized on repeat scan (median time to scan: 95 days): Of the 16 patients, 1 had underlying calcified plaque which recanalized to severe stenosis. The other 15 patients had homogenous, echoic-hypoechoic lesions that recanalized to extensive, severe stenosis in 6 and focal, severe stenosis in 3.

Conclusions: Symptomatic carotid occlusion is not common in our patients. However, about 20% showed evidence of recanalization and more than half to severe stenosis. Such patients may benefit from carotid revascularization. This highlights the importance of repeating carotid studies in Acute Carotid Occlusion. Further prospective studies may provide insights into the recanalization mechanisms of an occluded carotid artery.

Patients with single distal MCA perfusion lesions have a high rate of good outcome with or without reperfusion

BACKGROUND

Reperfusion is associated with good functional outcome after stroke. However, minimal data are available regarding the effect of reperfusion on clinical outcome and infarct growth in patients with distal MCA branch occlusions.

AIM

The aim of this study was to evaluate this association and to determine the impact of the perfusion-diffusion mismatch.

METHODS

Individual patient data from three stroke studies (EPITHET, DEFUSE and DEFUSE 2) with baseline MRI profiles and reperfusion status were pooled. Patients were included if they had a single cortical perfusion lesion on their baseline MRI that was consistent with a distal MCA branch occlusion. Good functional outcome was defined as a score of 0-2 on the modified Rankin Scale at day 90 and infarct growth was defined as change in lesion volume between the baseline DWI and the final T2/FLAIR.

RESULTS

Thirty patients met inclusion criteria. Eighteen (60%) had a good functional outcome and twenty (67%) had reperfusion. Reperfusion was not associated with good functional outcome in the overall cohort (OR: 1·0, 95% CI 0·2-4·7) and also not in the subset of patients with a PWI-DWI mismatch (n = 17; OR: 0·7, 95% CI 0·1-5·5). Median infarct growth was modest and not significantly different between patients with (0 ml) and without reperfusion (6 ml); P = 0·2.

CONCLUSIONS

The overall high rate of good outcomes in patients with distal MCA perfusion lesions might obscure a potential benefit from reperfusion in this population. A larger pooled analysis evaluating the effect of reperfusion in patients with distal MCA branch occlusions is warranted as confirmation of our results could have implications for the design of future stroke trials.

Retinal Microvascular Changes and Risk of Stroke

Background and Purpose—

To examine the relationship between retinal microvascular measures and incident stroke in an Asian Malay population.

Methods—

We conducted a prospective, population-based cohort study of Asian Malay persons 40 to 80 years at baseline. Retinal microvascular signs were assessed from baseline retinal photographs including quantitative retinal microvascular parameters (caliber, branching angle, tortuosity, and fractal dimension) and qualitative retinopathy signs. Incident stroke cases were identified during the follow-up period. Cox proportional-hazards regression and incremental usefulness analysis (calibration, discrimination, and reclassification) were performed.

Results—

A total of 3189 participants were free of prevalent stroke at baseline. During the follow-up (median, 4.41 years), 51 (1.93%) participants had an incident stroke event. In Cox proportional-hazards models adjusting for established stroke predictors (age, sex, systolic blood pressure, total cholesterol, low-density lipoprotein cholesterol, smoking, glycosylated hemoglobin, and antihypertensive medication), retinopathy (hazard ratio, 1.94; 95% confidence interval, 1.01–3.72) and larger retinal venular caliber (hazard ratio, 3.28; 95% confidence interval, 1.30–8.26, comparing fourth versus first quartiles) were associated with risk of stroke. Compared with the model with only established risk factors, the addition of retinal measures improved the prediction of stroke (C-Statistic 0.826 versus 0.792; P =0.017) and correctly reclassified 5.9% of participants with incident stroke and 3.4% of participants with no incident stroke.

Conclusions—

Retinal microvascular changes are related to an increased risk of stroke in Asian Malay, consistent with data from white populations. Retinal imaging improves the discrimination and stratification of stroke risk beyond that of established risk factors by a significant but small margin.

Inflammatory Markers and Their Association with Post Stroke Cognitive Decline

Background

Population-based studies have demonstrated the association of inflammation and cognitive impairment. However, few studies to date have examined this association in ischemic stroke patients.

Aims

The study aims to determine the association between inflammatory markers and cognitive impairment.

Methods

Ischemic stroke patients with baseline neuropsychological assessments at three-months poststroke were followed up with annual neuropsychological assessments for up to five-years. Inflammatory markers (C-reactive protein, interleukin 1β, interleukin 6, interleukin 8, interleukin 10, interleukin 12, and tumor necrosis factor-α) were assayed, and logistic regression analyses were performed to determine associations between inflammatory markers and both baseline cognitive status and subsequent cognitive decline.

Results

There were 243 ischemic stroke patients in the study. In multivariable ordinal logistic regression analysis, age, education, ethnicity, stroke subtype, and interleukin 8 (OR 1·23 CI 1·05–1·44) levels were independently associated with baseline cognitive status. In multivariable logistic regression analyses, age, gender, recurrent strokes, and interleukin 12 (OR 25·02 CI 3·73 to 168·03) were independent predictors of subsequent cognitive decline.

Conclusions

Following ischemic stroke, higher serum interleukin 8 is independently associated with baseline cognitive impairment while higher serum interleukin 12 is associated with subsequent cognitive decline.

Worse stroke outcome in atrial fibrillation is explained by more severe hypoperfusion, infarct growth, and hemorrhagic transformation

BACKGROUND

Atrial fibrillation is associated with greater baseline neurological impairment and worse outcomes following ischemic stroke. Previous studies suggest that greater volumes of more severe baseline hypoperfusion in patients with history of atrial fibrillation may explain this association. We further investigated this association by comparing patients with and without atrial fibrillation on initial examination following stroke using pooled multimodal magnetic resonance imaging and clinical data from the Echoplanar Imaging Thrombolytic Evaluation Trial and the Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution studies.

METHODS

Echoplanar Imaging Thrombolytic Evaluation Trial was a trial of 101 ischemic stroke patients randomized to intravenous tissue plasminogen activator or placebo, and Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution was a prospective cohort of 74 ischemic stroke patients treated with intravenous tissue plasminogen activator at three to six hours following symptom onset. Patients underwent multimodal magnetic resonance imaging before treatment, at three to five days and three-months after stroke in Echoplanar Imaging Thrombolytic Evaluation Trial; before treatment, three to six hours after treatment and one-month after stroke in Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution. Patients were assessed with the National Institutes of Health Stroke Scale and the modified Rankin scale before treatment and at three-months after stroke. Patients were categorized into definite atrial fibrillation (present on initial examination), probable atrial fibrillation (history but no atrial fibrillation on initial examination), and no atrial fibrillation. Perfusion data were reprocessed with automated magnetic resonance imaging analysis software (RAPID, Stanford University, Stanford, CA, USA). Hypoperfusion volumes were defined using time to maximum delays in two-second increments from >4 to >8 s. Hemorrhagic transformation was classified according to the European Cooperative Acute Stroke Studies criteria.

RESULTS

Of the 175 patients, 28 had definite atrial fibrillation, 30 probable atrial fibrillation, 111 no atrial fibrillation, and six were excluded due to insufficient imaging data. At baseline, patients with definite atrial fibrillation had more severe hypoperfusion (median time to maximum >8 s, volume 48 vs. 29 ml, P = 0.02) compared with patients with no atrial fibrillation. At outcome, patients with definite atrial fibrillation had greater infarct growth (median volume 47 vs. 8 ml, P = 0.001), larger infarcts (median volume 75 vs. 23 ml, P = 0.001), more frequent parenchymal hematoma grade hemorrhagic transformation (30% vs. 10%, P = 0.03), worse functional outcomes (median modified Rankin scale score 4 vs. 3, P = 0.03), and higher mortality (36% vs. 16%, P = 0·.3) compared with patients with no atrial fibrillation. Definite atrial fibrillation was independently associated with increased parenchymal hematoma (odds ratio = 6.05, 95% confidence interval 1.60-22.83) but not poor functional outcome (modified Rankin scale 3-6, odds ratio = 0.99, 95% confidence interval 0.35-2.80) or mortality (odds ratio = 2.54, 95% confidence interval 0.86-7.49) three-months following stroke, after adjusting for other baseline imbalances.

CONCLUSION

Atrial fibrillation is associated with greater volumes of more severe baseline hypoperfusion, leading to higher infarct growth, more frequent severe hemorrhagic transformation and worse stroke outcomes.

Advanced imaging improves prediction of hemorrhage after stroke thrombolysis

OBJECTIVE

Very low cerebral blood volume (VLCBV), diffusion, and hypoperfusion lesion volumes have been proposed as predictors of hemorrhagic transformation following stroke thrombolysis. We aimed to compare these parameters, validate VLCBV in an independent cohort using DEFUSE study data, and investigate the interaction of VLCBV with regional reperfusion.

METHODS

The EPITHET and DEFUSE studies obtained diffusion and perfusion magnetic resonance imaging (MRI) in patients 3 to 6 hours from onset of ischemic stroke. EPITHET randomized patients to tissue plasminogen activator (tPA) or placebo, and all DEFUSE patients received tPA. VLCBV was defined as cerebral blood volume<2.5th percentile of brain contralateral to the infarct. Parenchymal hematoma (PH) was defined using European Cooperative Acute Stroke Study criteria. Reperfusion was assessed using subacute perfusion MRI coregistered to baseline imaging.

RESULTS

In DEFUSE, 69 patients were analyzed, including 9 who developed PH. The >2 ml VLCBV threshold defined in EPITHET predicted PH with 100% sensitivity, 72% specificity, 35% positive predictive value, and 100% negative predictive value. Pooling EPITHET and DEFUSE (163 patients, including 23 with PH), regression models using VLCBV (p<0.001) and tPA (p=0.02) predicted PH independent of clinical factors better than models using diffusion or time to maximum>8 seconds lesion volumes. Excluding VLCBV in regions without reperfusion improved specificity from 61 to 78% in the pooled analysis.

INTERPRETATION

VLCBV predicts PH after stroke thrombolysis and appears to be a more powerful predictor than baseline diffusion or hypoperfusion lesion volumes. Reperfusion of regions of VLCBV is strongly associated with post-thrombolysis PH. VLCBV may be clinically useful to identify patients at significant risk of hemorrhage following reperfusion.

Abstract WMP53: Vitamin D Levels Are Lower In Acute Ischemic Stroke Patients Compared To Matched Controls

Introduction: Vitamin D deficiency is increasingly recognized as a global pandemic. In longitudinal healthy population studies, vitamin D deficiency is associated with increased incidence of ischemic stroke. We compared serum 25-OH vitamin D levels between Asian ischemic stroke patients within 1 week of stroke onset with age and gender matched healthy individuals.

Methods: We prospectively recruited 133 consecutive Asian acute ischemic stroke patients admitted to the Singapore General Hospital. Blood samples were collected within seven days of stroke onset. Stroke patients were matched for age and gender to individuals with no history of stroke from a database of healthy Asian controls. Serum 25-OH vitamin D was measured using Roche competitive electrochemiluminescence immunoassay for both stroke patients and healthy controls in the same laboratory. Vitamin D deficiency was defined as serum 25-OH vitamin D <20 μg/L and insufficiency as 20-40 μg/L. Matched statistical analyses were performed using Wilcoxon and McNemar tests.

Results: Among the 133 matched pairs of ischemic stroke patients and healthy controls, median age was 60 years and 75% are males. Median serum 25-OH vitamin D level was lower among stroke patients (23.2 IQR 16.65-29.60 μg/L) compared to healthy controls (28.9 IQR 21.75-35.50 μg/L) (p<0.0001). Stroke patients had a higher prevalence of vitamin D deficiency (39%) compared to healthy controls (20%) (p<0.0001). A high proportion of stroke patients had insufficient vitamin D compared to healthy controls (95% vs 84%, p=0.007). Corrected serum calcium was lower in stroke patients (median 2.26 mmol/L IQR 2.21-2.35) than controls (median 2.34 mmol/L IQR 2.28- 2.41) (p<0.0001). There was no difference in serum phosphate (p=0.266) and parathyroid hormone levels (p=0.807).

Conclusion: This cross-sectional study of 25-OH vitamin D levels in Asian patients within 1 week of ischemic stroke onset contributes to the growing evidence that vitamin D insufficiency/ deficiency is a stroke risk factor. Vitamin D measurement within 1 week of stroke onset likely reflects pre-stroke levels and is not influenced by post-stroke effects. Our findings provide impetus for future studies to investigate if vitamin D supplementation reduces stroke incidence.

Abstract TP47: Infarct Growth Does Not Predict Functional Outcome For Small Vessel Stroke

Introduction: Infarct growth has been shown to be a predictor of clinical outcome following ischemic stroke and has been used as a surrogate in reperfusion studies. There are no data whether the association of infarct growth and clinical outcome depends on stroke etiology. Furthermore, there is uncertainty on how to handle small volume infarcts with some studies excluding them from analyses. We studied the relationship between infarct growth and functional outcome in stroke patients with small volume infarcts for subgroups with small and non-small vessel etiologies.

Methods: We studied 37 patients in the MRI substudy of the Efficacy of Nitric Oxide in Stroke (ENOS) trial with baseline infarct volumes of ≤5ml. None of the patients were treated with reperfusion strategies. Brain MRI was performed serially at baseline within 48 hours of onset, on days 7 and 90. Infarct growth was measured as the volume difference between final T2 and baseline DWI lesions. Good functional outcome was defined as day 90 modified Rankin score ≤2 and poor as >2.

Results: Among the 26 patients with underlying small vessel etiology, there was no difference between those with good and poor outcomes in terms of absolute [median 0.0 (IQR -0.4 to 1.1) vs 0.1 (-0.7 to 0.2) mL, p=0.802] and relative infarct growth [median -3 (-27 to 81) vs 8 (-46 to 10) %, p=0.802]. However, in the 11 patients with etiologies other than small vessel disease, patients with good outcome had less absolute [median -0.9 (-1.6 to 0.7) vs 3.2 (0.2 to 9.1) mL, p=0.033] and relative infarct growth [median -59 (-81 to 9) vs 154 (35 to 292) %, p=0.019] compared to those with poor outcome.

Discussion: In small volume strokes, infarct growth was not associated with functional outcome for small vessel stroke although there was a significant association for other stroke etiologies. This novel finding in this small sample should be confirmed in larger studies. Our findings are expected as small vessel stroke involves occlusion of penetrating arterioles which supply small, limited yet strategically important brain regions. Thus, while infarct growth may be a suitable surrogate for clinical outcomes for small volume infarcts due to non-small vessel disease, but it may not be for small vessel strokes.

The Effects of Alteplase 3 to 6 Hours After Stroke in the EPITHET–DEFUSE Combined Dataset

Background and Purpose—

Two phase 2 studies of alteplase in acute ischemic stroke 3 to 6 hours after onset, Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET; a randomized, controlled, double-blinded trial), and Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution Study (DEFUSE; open-label, treatment only) using MR imaging-based outcomes have been conducted. We have pooled individual patient data from these to assess the response to alteplase. The primary hypothesis was that alteplase would significantly attenuate infarct growth compared with placebo in mismatch-selected patients using coregistration techniques.

Methods—

The EPITHET–DEFUSE study datasets were pooled while retaining the original inclusion and exclusion criteria. Significant hypoperfusion was defined as a Tmax delay >6 seconds), and coregistration techniques were used to define MR diffusion-weighted imaging/perfusion-weighted imaging mismatch. Neuroimaging, parameters including reperfusion, recanalization, symptomatic intracerebral hemorrhage, and clinical outcomes were assessed. Alteplase and placebo groups were compared for the primary outcome of infarct growth as well for secondary outcome measures.

Results—

From 165 patients with adequate MR scans in the EPITHET–DEFUSE pooled data, 121 patients (73.3%) were found to have mismatch. For the primary outcome analysis, 60 patients received alteplase and 41 placebo. Mismatch patients receiving alteplase had significantly attenuated infarct growth compared with placebo ( P =0.025). The reperfusion rate was also increased (62.7% vs 31.7%; P =0.003). Mortality and clinical outcomes were not different between groups.

Conclusions—

The data provide further evidence that alteplase significantly attenuates infarct growth and increases reperfusion compared with placebo in the 3- to 6- hour time window in patients selected based on MR penumbral imaging.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00238537

Multiparametric MRI and CT models of infarct core and favorable penumbral imaging patterns in acute ischemic stroke

BACKGROUND AND PURPOSE

Objective imaging methods to identify optimal candidates for late recanalization therapies are needed. The study goals were (1) to develop magnetic resonance imaging (MRI) and computed tomography (CT) multiparametric, voxel-based predictive models of infarct core and penumbra in acute ischemic stroke patients, and (2) to develop patient-level imaging criteria for favorable penumbral pattern based on good clinical outcome in response to successful recanalization.

METHODS

An analysis of imaging and clinical data was performed on 2 cohorts of patients (one screened with CT, the other with MRI) who underwent successful treatment for large vessel, anterior circulation stroke. Subjects were divided 2:1 into derivation and validation cohorts. Pretreatment imaging parameters independently predicting final tissue infarct and final clinical outcome were identified.

RESULTS

The MRI and CT models were developed and validated from 34 and 32 patients, using 943 320 and 1 236 917 voxels, respectively. The derivation MRI and 2-branch CT models had an overall accuracy of 74% and 80%, respectively, and were independently validated with an accuracy of 71% and 79%, respectively. The imaging criteria of (1) predicted infarct core ≤90 mL and (2) ratio of predicted infarct tissue within the at-risk region ≤70% identified patients as having a favorable penumbral pattern with 78% to 100% accuracy.

CONCLUSIONS

Multiparametric voxel-based MRI and CT models were developed to predict the extent of infarct core and overall penumbral pattern status in patients with acute ischemic stroke who may be candidates for late recanalization therapies. These models provide an alternative approach to mismatch in predicting ultimate tissue fate.

Differing Associations of White Matter Lesions and Lacunar Infarction with Retinal Microvascular Signs

Background

White matter lesions (WML) and lacunar infarcts (LI) are believed to have microvascular etiologies but the exact microvascular changes occurring in each is unclear. Aim Using the retina as a proxy, we assessed retinal microvascular changes in WML and LI.

Methods

We prospectively recruited 1211 acute stroke patients. Four subgroups were identified from neuroimaging: WML alone, LI alone, both WML and LI, neither WML nor LI. Masked retinal photographs identified retinopathy and retinal arteriolar wall signs and measured retinal vascular caliber.

Results

Compared with 448 controls with neither WML nor LI, 384 patients with only WML were more likely to have retinopathy [odds ratio (OR) 1·5, 95% confidence interval (CI) 1·1 to 2·1] and enhanced arteriolar light reflex (OR 1·6, 95% CI 1·1 to 2·3); 200 patients with only LI were more likely to have arteriolar narrowing (OR 1·6, 95% CI 1·1 to 2·3) and enhanced arteriolar light reflex (OR 1·6, 95% CI 1·0 to 2·4); and 179 patients with both WML and LI were more likely to have arteriovenous nicking (OR 1·7, 95% CI 1·1 to 2·6), enhanced arteriolar light reflex (OR 2·0, 95% CI 1·3 to 3·2) and wider venules (OR 2·3, 95% CI 1·4 to 3·6). All analyses were adjusted for age, gender, study site and cardiovascular risk factors.

Conclusion

Both WML and LI were associated with retinal microvascular signs, supporting a microvascular etiology. Differing patterns of association suggest different mechanisms may predominate, e.g. greater endothelial permeability in WML, and ischemia associated with arteriolar wall disease in LI.

Abstract 61: Reperfusion Beyond 4.5 Hours Reduces Infarct Growth And Improves Clinical Outcome

Background and purpose: The ECASS 3 study demonstrated efficacy of intravenous thrombolysis up to 4.5h after stroke onset. It has been hypothesized that some patients have tissue at risk and an acceptably low hemorrhage risk beyond 4.5h. Imaging based selection may help identify these patients for late reperfusion therapies. No randomized data have shown efficacy of tPA or reperfusion later than 4.5h after onset. We analysed the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET) data to assess the effect of treatment and reperfusion on attenuation of infarct growth in the 4.5 to 6 hour time window.

Methods: Patients were randomized to placebo or tissue plasminogen activator (tPA) between 4.5-6h from stroke onset (without using imaging selection criteria). Pre-treatment DWI and day 90 T2-weighted lesion volumes (average of manually outlined lesions by 2 independent raters) were compared to assess the influence of tPA and reperfusion on absolute and relative infarct growth. Day 3 volume was used when day 90 data was missing. The effect of tPA on reperfusion was also assessed. Good clinical outcome was defined as a National Institute of Health Stroke Scale (NIHSS) at day 90 0-1 or improvement ≥ 8 from baseline. Good functional outcome was defined as modified Rankin Scale (mRS) 0-2.

Results: Of 69 patients treated 4.5-6hrs hours after stroke onset, infarct growth could be assessed in 63. The median relative growth was significantly lower in the tPA group compared to placebo (0.94 vs 1.68, p=0.025). There was a nonsignificant trend towards lower absolute growth (-0.17mL vs 9.56mL, p=0.069). Reperfusion markedly reduced relative (0.80 vs 1.89, p<0.001) and absolute infarct growth (-2.49mL vs 39.50mL, p<0.001). Reperfusion was more likely in the tPA group (57.7 vs 25.0% p=0.026) and was associated with better clinical and functional outcomes (86.4% vs 28.1% p<0.001 and 72.7 vs 34.4% p=0.012).

Conclusion: Thrombolysis after 4.5 hours reduced infarct growth and increased the rate of reperfusion. The strong positive effect of reperfusion on clinical and functional outcomes in this later time window is evidence of persisting salvageable ischemic penumbra. This supports continuing efforts to extend the treatment window for reperfusion therapies.

Abstract 92: MRI Patient Selection In Acute Stroke Trials: Implications For Sample Size

Background: MRI selection of patients with acute stroke may reduce the required sample size for randomized controlled trials of interventions aimed at restoring blood flow. The Target Mismatch pattern has been proposed as a MRI-marker that can differentiate patients who are likely to benefit from reperfusion from those who will have no effect from or may be harmed by reperfusion. The Target Mismatch pattern is present in approximately 50% of stroke patients with a middle cerebral artery occlusion who present in the 3-6 hour time-window. The pattern is based on the following PWI and DWI criteria: ratio of Tmax>6s over DWI volume >1.2, difference between Tmax>6s and DWI volume >10ml, and DWI volume <100ml. The aim of this study was to compare the required sample size of acute stroke studies that use MRI selection to that of studies which do not use MRI selection.

Methods: All sample size calculations were based on an alpha of 0.05 in a two-sided test and a desired power of 0.8. MRI patient selection was assumed to be according to Target Mismatch criteria. The primary study outcome was assumed to be good functional outcome, defined as a modified Rankin Scale of 0-2 at 90 days. Other assumptions for the sample size calculations were based on data from the literature and data from the pooled EPITHET-DEFUSE database regarding patients with middle cerebral artery (MCA) occlusions treated up to six hours after symptom onset. The spontaneous reperfusion rate in this population was assumed to be 0.22. For MRI-selected mismatch patients the rate of good functional outcome was assumed to be 0.73 with reperfusion and 0.30 without reperfusion. For unselected patients, the rate of favorable clinical outcome was assumed to be 0.67 with reperfusion and 0.41 without reperfusion.

Results: A trial of an intervention that leads to reperfusion of the MCA in 45% of patients would require 396 patients per group if MRI selection criteria were applied and 1096 patients per group without MRI selection criteria. A trial of an intervention that has a 70% reperfusion rate would require 92 patients in each arm if MRI selection criteria were applied versus 251 patients per arm if patients were enrolled without MRI selection. (see figure )

Conclusion: MRI selection can markedly reduce the required sample size of randomized controlled stroke trials in the delayed time-window. This advantage needs to be balanced against the potential drawbacks of using a MRI-marker as an inclusion criterion for a randomized controlled trial.

Abstract 95: Regional Very Low Cerebral Blood Volume with Subsequent Local Reperfusion Predicts Hemorrhagic Transformation in Acute Ischemic Stroke

Background and Purpose Regions of very low cerebral blood volume (VLCBV) on MR perfusion imaging have been shown to predict hemorrhagic transformation (HT) following stroke thrombolysis. We tested the hypothesis that local reperfusion in a region of VLCBV is a pre-requisite for hemorrhagic transformation using pooled imaging data from the EPITHET and DEFUSE studies.

Methods Standard CBV maps were calculated and smoothed (Gaussian) to reduce noise. The volume of VLCBV was calculated within the acute Tmax>4sec perfusion lesion using fully automated techniques and a range of VLCBV thresholds relative to CBV values in the non-stroke hemisphere. Receiver operating characteristic (ROC) analysis was used to determine the optimal definition and threshold of VLCBV to predict parenchymal hematoma (PH, ECASS definition). Regional reperfusion was assessed using co-registered subacute Tmax perfusion images (DEFUSE 3-6hrs post thrombolysis, EPITHET 3-5 days post thrombolysis/placebo). The risk of PH associated with VLCBV was assessed with and without exclusion of regions of VLCBV within persistently hypoperfused regions.

Results Of 145 patients with baseline perfusion imaging, 22 (15.2%) had PH (13 PH1, 9 PH2). A VLCBV definition of either <2.5 th percentile of the contralateral CBV distribution (VLCBV<2.5pctile) or <15% of the mean contralateral CBV (VLCBV<15%) had similar performance in predicting PH (AUC 0.73 for both). To achieve sensitivity of 95% required a VLCBV<2.5pctile threshold of >2mL (specificity 47%) or a VLCBV<15% threshold of >0.5mL (specificity 41%). There were 130 patients with subacute perfusion imaging, at which time 15 (11.5%) had developed PH. A further 3 patients (without reperfusion at subacute MRI) later developed PH and were excluded as reperfusion status at the time of PH was unknown. In the remaining 127 patients, the AUC for PH increased from 0.77 to 0.92 (p<0.001, VLCBV<2.5pctile definition) when regions of VLCBV without reperfusion on subacute imaging were excluded. The specificity of the >2mL threshold (VLCBV<2.5pctile) increased from 46 to 75%, positive predictive value increased from 20 to 35%, likelihood ratio for PH increased from 1.9 to 4.0 (sensitivity and negative predictive value were both 100% in these 127 patients). No patient developed PH at the time of subacute imaging in the absence of local reperfusion, including one patient where reperfusion of basal ganglia infarction had occurred (with CBV normalisation) prior to thrombolysis.

Conclusions Local reperfusion is a critical factor in determining the risk of HT associated with regional VLCBV. This is consistent with the hypothesis that the severe ischemia represented by VLCBV is associated with focal blood-brain-barrier disruption and potential HT should reperfusion subsequently occur. Assessment of VLCBV can be automated and may be useful in clinical risk-benefit decisions regarding thrombolysis.

Greater effect of stroke thrombolysis in the presence of arterial obstruction

OBJECTIVE

Recanalization of arterial obstruction is associated with improved clinical outcomes. There are no controlled data demonstrating whether arterial obstruction status predicts the treatment effect of intravenous (IV) tissue plasminogen activator (tPA). We aimed to determine if the presence of arterial obstruction improves the treatment effect of IV tPA over placebo in attenuating infarct growth.

METHODS

We analyzed 175 ischemic stroke patients treated in the 3-6 hour time window from the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET) trial (randomized to IV tPA or placebo) and Diffusion and perfusion imaging Evaluation For Understanding Stroke Evolution (DEFUSE) study (all treated with IV tPA). Infarct growth was calculated as the difference between baseline diffusion-weighted imaging (DWI) and final T2 lesion volumes. Baseline arterial obstruction of large intracranial arteries was graded on magnetic resonance angiography (MRA).

RESULTS

Among the 116 patients with adequate baseline MRA and final lesion assessment, 72 had arterial obstruction (48 tPA, 24 placebo) and 44 no arterial obstruction (33 tPA, 11 placebo). Infarct growth was lower in the tPA than placebo group (median difference 26ml, 95% confidence interval [CI], 1-50) in patients with arterial obstruction, but was similar in patients with no arterial obstruction (median difference 5ml, 95%CI, -3 to 9). Infarct growth attenuation with tPA over placebo treatment was greater among patients with arterial obstruction than those without arterial obstruction by a median of 32ml (95%CI, 21-43, p < 0.001).

INTERPRETATION

The treatment effect of IV tPA over placebo was greater with baseline arterial obstruction, supporting arterial obstruction status as a consideration in selecting patients more likely to benefit from IV thrombolysis.

The infarct core is well represented by the acute diffusion lesion: sustained reversal is infrequent

Diffusion-weighted imaging (DWI) is commonly used to assess irreversibly infarcted tissue but its accuracy is challenged by reports of diffusion lesion reversal (DLR). We investigated the frequency and implications for mismatch classification of DLR using imaging from the EPITHET (Echoplanar Imaging Thrombolytic Evaluation Trial) and DEFUSE (Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution) studies. In 119 patients (83 treated with IV tissue plasminogen activator), follow-up images were coregistered to acute diffusion images and the lesions manually outlined to their maximal visual extent in diffusion space. Diffusion lesion reversal was defined as voxels of acute diffusion lesion that corresponded to normal brain at follow-up (i.e., final infarct, leukoaraiosis, and cerebrospinal fluid (CSF) voxels were excluded from consideration). The appearance of DLR was visually checked for artifacts, the volume calculated, and the impact of adjusting baseline diffusion lesion volume for DLR volume on perfusion-diffusion mismatch analyzed. Median DLR volume reduced from 4.4 to 1.5 mL after excluding CSF/leukoaraiosis. Visual inspection verified 8/119 (6.7%) with true DLR, median volume 2.33 mL. Subtracting DLR from acute diffusion volume altered perfusion-diffusion mismatch (T(max)>6 seconds, ratio>1.2) in 3/119 (2.5%) patients. Diffusion lesion reversal between baseline and 3 to 6 hours DWI was also uncommon (7/65, 11%) and often transient. Clinically relevant DLR is uncommon and rarely alters perfusion-diffusion mismatch. The acute diffusion lesion is generally a reliable signature of the infarct core.

Fluid-attenuated inversion recovery hyperintensity in acute ischemic stroke may not predict hemorrhagic transformation

BACKGROUND

Fluid-attenuated inversion recovery (FLAIR) hyperintensity within an acute cerebral infarct may reflect delayed onset time and increased risk of hemorrhage after thrombolysis. Given the important implications for clinical practice, we examined the prevalence of FLAIR hyperintensity in patients 3-6 h from stroke onset and its relationship to parenchymal hematoma (PH).

METHODS

Baseline DWI and FLAIR imaging with subsequent hemorrhage detection (ECASS criteria) were prospectively obtained in patients 3-6 h after stroke onset from the pooled EPITHET and DEFUSE trials. FLAIR hyperintensity within the region of the acute DWI lesion was rated qualitatively (dichotomized as visually obvious or subtle (i.e. only visible after careful windowing)) and quantitatively (using relative signal intensity (RSI)). The association of FLAIR hyperintensity with hemorrhage was then tested alongside established predictors (very low cerebral blood volume (VLCBV) and diffusion (DWI) lesion volume) in logistic regression analysis.

RESULTS

There were 49 patients with pre-treatment FLAIR imaging (38 received tissue plasminogen activator (tPA), 5 developed PH). FLAIR hyperintensity within the region of acute DWI lesion occurred in 48/49 (98%) patients, was obvious in 18/49 (37%) and subtle in 30/49 (61%). Inter-rater agreement was 92% (κ = 0.82). The prevalence of obvious FLAIR hyperintensity did not differ between studies obtained in the 3-4.5 h and 4.5-6 h time periods (40% vs. 33%, p = 0.77). PH was poorly predicted by obvious FLAIR hyperintensity (sensitivity 40%, specificity 64%, positive predictive value 11%). In univariate logistic regression, VLCBV (p = 0.02) and DWI lesion volume (p = 0.03) predicted PH but FLAIR lesion volume (p = 0.87) and RSI (p = 0.11) did not. In ordinal logistic regression for hemorrhage grade adjusted for age and baseline stroke severity (NIHSS), increased VLCBV (p = 0.002) and DWI lesion volume (p = 0.003) were associated with hemorrhage but FLAIR lesion volume (p = 0.66) and RSI (p = 0.35) were not.

CONCLUSIONS

Visible FLAIR hyperintensity is almost universal 3-6 h after stroke onset and did not predict subsequent hemorrhage in this dataset. Our findings question the value of excluding patients with FLAIR hyperintensity from reperfusion therapies. Larger studies are required to clarify what implications FLAIR-positive lesions have for patient selection.

RAPID automated patient selection for reperfusion therapy: a pooled analysis of the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET) and the Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution (DEFUSE) Study

BACKGROUND AND PURPOSE

The aim of this study was to determine if automated MRI analysis software (RAPID) can be used to identify patients with stroke in whom reperfusion is associated with an increased chance of good outcome.

METHODS

Baseline diffusion- and perfusion-weighted MRI scans from the Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution study (DEFUSE; n=74) and the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET; n=100) were reprocessed with RAPID. Based on RAPID-generated diffusion-weighted imaging and perfusion-weighted imaging lesion volumes, patients were categorized according to 3 prespecified MRI profiles that were hypothesized to predict benefit (Target Mismatch), harm (Malignant), and no effect (No Mismatch) from reperfusion. Favorable clinical response was defined as a National Institutes of Health Stroke Scale score of 0 to 1 or a ≥ 8-point improvement on the National Institutes of Health Stroke Scale score at Day 90.

RESULTS

In Target Mismatch patients, reperfusion was strongly associated with a favorable clinical response (OR, 5.6; 95% CI, 2.1 to 15.3) and attenuation of infarct growth (10 ± 23 mL with reperfusion versus 40 ± 44 mL without reperfusion; P<0.001). In Malignant profile patients, reperfusion was not associated with a favorable clinical response (OR, 0.74; 95% CI, 0.1 to 5.8) or attenuation of infarct growth (85 ± 74 mL with reperfusion versus 95 ± 79 mL without reperfusion; P=0.7). Reperfusion was also not associated with a favorable clinical response (OR, 1.05; 95% CI, 0.1 to 9.4) or attenuation of lesion growth (10 ± 15 mL with reperfusion versus 17 ± 30 mL without reperfusion; P=0.9) in No Mismatch patients.

CONCLUSIONS

MRI profiles that are associated with a differential response to reperfusion can be identified with RAPID. This supports the use of automated image analysis software such as RAPID for patient selection in acute stroke trials.

Refining the definition of the malignant profile: insights from the DEFUSE-EPITHET pooled data set

BACKGROUND AND PURPOSE

To refine the definition of the malignant magnetic resonance imaging profile in acute stroke patients using baseline diffusion-weighted magnetic resonance imaging (DWI) and perfusion-weighted magnetic resonance imaging (PWI) findings from the pooled DEFUSE/EPITHET database.

METHODS

Patients presenting with acute stroke within 3 to 6 hours from symptom onset were treated with tissue plasminogen activator or placebo. Baseline and follow-up DWI and PWI images from both studies were reprocessed using the same software program. A receiver operating characteristic curve analysis was used to identify Tmax and DWI volumes that optimally predicted poor outcomes (modified Rankin Scale 5-6) at 90 days in patients who achieved reperfusion.

RESULTS

Sixty-five patients achieved reperfusion and 46 did not reperfuse. Receiver operating characteristic analysis identified a PWI (Tmax>8 s) volume of >85 mL as the optimal definition of the malignant profile. Eighty-nine percent of malignant profile patients had poor outcome with reperfusion versus 39% of patients without reperfusion (P=0.02). Parenchymal hematomas occurred more frequently in malignant profile patients who experienced reperfusion versus no reperfusion (67% versus 11%, P<0.01). DWI analysis identified a volume of 80 mL as the best DWI threshold, but this definition was less sensitive than were PWI-based definitions.

CONCLUSIONS

Stroke patients likely to suffer parenchymal hemorrhages and poor outcomes following reperfusion can be identified from baseline magnetic resonance imaging findings. The current analysis demonstrates that a PWI threshold (Tmax>8 s) of approximately 100 mL is appropriate for identifying these patients. Exclusion of malignant profile patients from reperfusion therapies may substantially improve the efficacy and safety of reperfusion therapies. Clinical Trial Registration Information- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00238537.

Associations of retinal microvascular signs and intracranial large artery disease

BACKGROUND AND PURPOSE

Intracranial large artery disease (ICLAD) is a major cause of ischemic stroke. Retinal microvascular changes are associated with stroke, including small vessel cerebral disease and extracranial carotid disease. We examined the relationship between ICLAD and retinal microvascular changes.

METHODS

This is a prospective cohort of 802 acute ischemic stroke patients. Retinal changes were assessed from photographs by graders masked to clinical data. ICLAD was evaluated using prespecified criteria.

RESULTS

ICLAD was not associated with ipsilateral retinal arteriolar/venular caliber, focal arteriolar narrowing, or arteriovenous nicking. Severe enhanced arteriolar light reflex was independently associated with any ICLAD (P=0.006) and severe ICLAD (P<0.001).

CONCLUSIONS

Enhanced arteriolar light reflex, but not retinal vessel caliber, was related to ICLAD. These data suggest that retinal microvascular signs have specific associations with large cerebral vessel disease.

EPITHET: Positive Result After Reanalysis Using Baseline Diffusion-Weighted Imaging/Perfusion-Weighted Imaging Co-Registration

BACKGROUND AND PURPOSE

the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET) was a prospective, randomized, double-blinded, placebo-controlled, phase II trial of alteplase between 3 and 6 hours after stroke onset. The primary outcome of infarct growth attenuation on MRI with alteplase in mismatch patients was negative when mismatch volumes were assessed volumetrically, without coregistration, which underestimates mismatch volumes. We hypothesized that assessing the extent of mismatch by coregistration of perfusion and diffusion MRI maps may more accurately allow the effects of alteplase vs placebo to be evaluated.

METHODS

patients were classified as having mismatch if perfusion-weighted imaging divided by coregistered diffusion-weighted imaging volume ratio was >1.2 and total coregistered mismatch volume was ≥ 10 mL. The primary outcome was a comparison of infarct growth in alteplase vs placebo patients with coregistered mismatch.

RESULTS

of 99 patients with baseline diffusion-weighted imaging and perfusion-weighted imaging, coregistration of both images was possible in 95 patients. Coregistered mismatch was present in 93% (88/95) compared to 85% (81/95) with standard volumetric mismatch. In the coregistered mismatch patients, of whom 45 received alteplase and 43 received placebo, the primary outcome measure of geometric mean infarct growth was significantly attenuated by a ratio of 0.58 with alteplase compared to placebo (1.02 vs 1.77; 95% CI, 0.33-0.99; P=0.0459).

CONCLUSIONS

when using coregistration techniques to determine the presence of mismatch at study entry, alteplase significantly attenuated infarct growth. This highlights the necessity for a randomized, placebo-controlled, phase III clinical trial of alteplase using penumbral selection beyond 3 hours.

The benefits of intravenous thrombolysis relate to the site of baseline arterial occlusion in the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET)

BACKGROUND AND PURPOSE

In ischemic stroke, the site of arterial obstruction has been shown to influence recanalization and clinical outcomes. However, this has not been studied in randomized controlled trials, nor has the impact of arterial obstruction site on reperfusion and infarct growth been assessed. We studied the influence of site and degree of arterial obstruction patients enrolled in the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET).

METHODS

EPITHET was a prospective, randomized, placebo-controlled trial of intravenous tissue plasminogen activator (tPA) in the 3- to 6-hour time window. Arterial obstruction site and degree were rated on magnetic resonance angiography blinded to treatment allocation and outcomes.

RESULTS

In 101 EPITHET patients, 87 had adequate quality magnetic resonance angiography, of whom 54 had baseline arterial obstruction. Infarct growth attenuation was greater in those with tPA treatment compared to placebo among patients with middle cerebral artery (MCA) obstruction (P=0.037). The treatment benefit of tPA over placebo in attenuating infarct growth was greater for MCA than internal carotid artery (ICA) obstruction (P=0.060). With tPA treatment, good clinical outcome was more likely with MCA than with ICA obstruction (P=0.005). Most patients with ICA obstruction did not achieve good clinical outcome, whether treated with tPA (100%) or placebo (77%). The study was underpowered to prove any treatment benefit of tPA among patients with any or severe degree of arterial obstruction.

CONCLUSIONS

Arterial obstruction site strongly predicts outcomes. ICA obstruction carries a uniformly poor prognosis, whereas good outcomes with MCA obstruction are associated with tPA therapy.

Regional very low cerebral blood volume predicts hemorrhagic transformation better than diffusion-weighted imaging volume and thresholded apparent diffusion coefficient in acute ischemic stroke

BACKGROUND AND PURPOSE

Currently, diffusion-weighted imaging (DWI) lesion volume is the most useful magnetic resonance imaging predictor of hemorrhagic transformation (HT). Preliminary studies have suggested that very low cerebral blood volume (VLCBV) predicts HT. We compared HT prediction by VLCBV and DWI using data from the EPITHET study.

METHODS

Normal-percentile CBV values were calculated from the nonstroke hemisphere. Whole-brain masks with CBV thresholds of the <0, 2.5, 5, and 10th percentiles were created. The volume of tissue with VLCBV was calculated within the acute DWI ischemic lesion. HT was graded as per ECASS criteria.

RESULTS

HT occurred in 44 of 91 patients. Parenchymal hematoma (PH) occurred in 13 (4 symptomatic) and asymptomatic hemorrhagic infarction (HI) in 31. The median volume of VLCBV was significantly higher in cases with PH. VLCBV predicted HT better than DWI lesion volume and thresholded apparent diffusion coefficient lesion volume in receiver operating characteristic analysis and logistic regression. A cutpoint at 2 mL VLCBV with the <2.5th percentile had 100% sensitivity for PH and, in patients treated with tissue plasminogen activator, defined a population with a 43% risk of PH (95% CI, 23% to 66%, likelihood ratio=16). VLCBV remained an independent predictor of PH in multivariate analysis with traditional clinical risk factors for HT.

CONCLUSIONS

VLCBV predicted HT after thrombolysis better than did DWI or apparent diffusion coefficient volume in this large patient cohort. The advantage was greatest in patients with smaller DWI volumes. Prediction was better in patients who recanalized. If validated in an independent cohort, the addition of VLCBV to prethrombolysis decision making may reduce the incidence of HT.