P-wave morphology and the risk of incident ischemic stroke in the Multi-Ethnic Study of Atherosclerosis

BACKGROUND AND PURPOSE

Emerging data suggest that left atrial disease may cause ischemic stroke in the absence of atrial fibrillation or flutter (AF). If true, this condition may provide a cause for many strokes currently classified as cryptogenic.

METHODS

Among 6741 participants in the Multi-Ethnic Study of Atherosclerosis who were free of clinically apparent cerebrovascular or cardiovascular disease (including AF) at baseline, we examined the association between markers of left atrial abnormality on a standard 12-lead ECG-specifically P-wave area, duration, and terminal force in lead V1-and the subsequent risk of ischemic stroke while accounting for incident AF.

RESULTS

During a median follow-up of 8.5 years, 121 participants (1.8%) had a stroke and 541 participants (8.0%) were diagnosed with AF. In Cox proportional hazards models adjusting for potential baseline confounders, P-wave terminal force in lead V1 was more strongly associated with incident stroke (hazard ratio per 1 SD increase, 1.21; 95% confidence interval, 1.02-1.44) than with incident AF (hazard ratio per 1 SD, 1.11; 95% confidence interval, 1.03-1.21). The association between P-wave terminal force in lead V1 and stroke was robust in numerous sensitivity analyses accounting for AF, including analyses that excluded those with any incident AF or modeled any incident AF as having been present from baseline.

CONCLUSIONS

We found an association between baseline P-wave morphology and incident stroke even after accounting for AF. This association may reflect an atrial cardiopathy that leads to stroke in the absence of AF.

The THRIVE Score Predicts Symptomatic Intracerebral Hemorrhage after Intravenous tPA Administration in SITS-MOST

Background

The Totaled Health Risks in Vascular Events (THRIVE) score is a clinical prediction score that predicts ischemic stroke outcomes in patients receiving intravenous tissue plasminogen activator, endovascular stroke treatment, or no acute therapy. We have previously found an association between THRIVE and risk of post-tissue plasminogen activator symptomatic intracranial hemorrhage in the National Institute of Neurological Disorders and Stroke (NINDS) tissue plasminogen activator trial and risk of radiographic hemorrhage in Virtual International Stroke Trials Archive.

Aims

The study aims to validate the relationship between THRIVE and symptomatic intracranial hemorrhage among tissue plasminogen activator-treated patients in the large Safe Implementation of Thrombolysis in Stroke – Monitoring Study (SITS-MOST).

Methods

This is a retrospective analysis of the prospective SITS-MOST to examine the relationship between THRIVE and symptomatic intracranial hemorrhage after tissue plasminogen activator treatment. Symptomatic intracranial hemorrhage after tissue plasminogen activator was defined according to each of three standard definitions: the NINDS, European Cooperative Acute Stroke Study (ECASS), and Safe Implementation of Thrombolysis in Stroke (SITS) criteria. Multivariable logistic regression was used to confirm the relationship of THRIVE and individual THRIVE components with the risk of symptomatic intracranial hemorrhage and to examine the relationship of THRIVE, symptomatic intracranial hemorrhage, and functional outcome.

Results

The odds ratio for symptomatic intracranial hemorrhage at each increased level of THRIVE score is 1·34 (95% CI 1·27 to 1·41, P < 0·001) for symptomatic intracranial hemorrhage by NINDS criteria, 1·36 (95% CI 1·27 to 1·46, P < 0·001) for symptomatic intracranial hemorrhage by ECASS criteria, and 1·21 (95% CI 1·09 to 1·36, P < 0·001) for symptomatic intracranial hemorrhage by SITS criteria. In receiver-operator characteristics analysis, the C-statistic for THRIVE prediction of symptomatic intracranial hemorrhage was 0·65 (95% CI 0·62 to 0·67) for symptomatic intracranial hemorrhage by NINDS criteria, 0·66 (95% CI 0·63 to 0·69) for symptomatic intracranial hemorrhage by ECASS criteria, and 0·61 (95% CI 0·56 to 0·66) for symptomatic intracranial hemorrhage by SITS criteria. Each component of the THRIVE score predicts the risk of symptomatic intracranial hemorrhage, with independent impact of each component in multivariable analysis.

Conclusions

The THRIVE score predicts the risk of symptomatic intracranial hemorrhage after intravenous tissue plasminogen activator administration. This external validation of the relationship between THRIVE and symptomatic intracranial hemorrhage in a prospective study further strengthens the role of the THRIVE score in the prediction of poststroke outcomes.

Cryptogenic subtype predicts reduced survival among cancer patients with ischemic stroke

BACKGROUND AND PURPOSE

Cryptogenic stroke is common in patients with cancer. Autopsy studies suggest that many of these cases may be because of marantic endocarditis, which is closely linked to cancer activity. We, therefore, hypothesized that among patients with cancer and ischemic stroke, those with cryptogenic stroke would have shorter survival.

METHODS

We retrospectively analyzed all adult patients with active systemic cancer diagnosed with acute ischemic stroke at a tertiary care cancer center from 2005 through 2009. Two neurologists determined stroke mechanisms by consensus. Patients were diagnosed with cryptogenic stroke if no specific mechanism could be determined. The diagnosis of marantic endocarditis was restricted to patients with cardiac vegetations on echocardiography or autopsy and negative blood cultures. Patients were followed until July 31, 2012, for the primary outcome of death. Kaplan-Meier statistics and the log-rank test were used to compare survival between patients with cryptogenic stroke and patients with known stroke mechanisms. Multivariate Cox proportional hazard analysis evaluated the association between cryptogenic stroke and death after adjusting for potential confounders.

RESULTS

Among 263 patients with cancer and ischemic stroke, 133 (51%) were cryptogenic. Median survival in patients with cryptogenic stroke was 55 days (interquartile range, 21-240) versus 147 days (interquartile range, 33-735) in patients with known stroke mechanisms (P<0.01). Cryptogenic stroke was independently associated with death (hazard ratio, 1.64; 95% confidence interval, 1.25-2.14) after adjusting for age, systemic metastases, adenocarcinoma histology, and functional status.

CONCLUSIONS

Cryptogenic stroke is independently associated with reduced survival in patients with active cancer and ischemic stroke.

Acute cerebrovascular disease occurring after hospital discharge for labor and delivery

BACKGROUND AND PURPOSE

The risk of stroke and other postpartum cerebrovascular disease (CVD) occurring after hospital discharge for labor and delivery is uncertain.

METHODS

We performed a retrospective cohort study using administrative databases to identify all pregnant women who were hospitalized for labor and delivery at nonfederal, acute care hospitals in California from 2005 to 2011 and who were discharged without an International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis of CVD. The primary outcome was an acute CVD composite defined as any ischemic stroke, intracranial hemorrhage, cerebral venous sinus thrombosis, pituitary apoplexy, carotid/vertebral artery dissection, hypertensive encephalopathy, or other acute CVD occurring after hospital discharge and before 6 weeks after labor and delivery. Descriptive statistics were used to estimate the incidence of postdischarge CVD. Multivariate logistic regression was used to evaluate the association between selected baseline factors and postdischarge CVD.

RESULTS

The rate of any postdischarge acute CVD was 14.8 per 100 000 patients (95% confidence interval [CI], 13.2-16.5). Risk factors for any acute CVD were eclampsia (odds ratio [OR], 10.1; 95% CI, 3.09-32.8), chronic kidney disease (OR, 5.4; 95% CI, 2.5-11.8), black race (OR, 2.5; 95% CI, 1.9-3.3), preeclampsia (OR, 2.1; 95% CI, 1.6-2.8), pregnancy-related hematologic disorders (OR, 1.8; 95% CI, 1.3-2.5), and age (OR, 1.5 per decade; 95% CI, 1.3-1.8).

CONCLUSIONS

The incidence of postpartum acute CVD after hospital discharge for labor and delivery is similar to rates reported for all postpartum events in previous publications, suggesting that a substantial proportion of postpartum CVD occurs after discharge.

Recurrent thromboembolic events after ischemic stroke in patients with cancer

OBJECTIVE

To determine the cumulative rate and characteristics of recurrent thromboembolic events after acute ischemic stroke in patients with cancer.

METHODS

We retrospectively identified consecutive adult patients with active systemic cancer diagnosed with acute ischemic stroke at a tertiary-care cancer center from 2005 through 2009. Two neurologists independently reviewed all electronic records to ascertain the composite outcome of recurrent ischemic stroke, myocardial infarction, systemic embolism, TIA, or venous thromboembolism. Kaplan-Meier statistics were used to determine cumulative outcome rates. In exploratory analyses, Cox proportional hazard analysis was used to evaluate potential independent associations between a priori selected clinical factors and recurrent thromboembolic events.

RESULTS

Among 263 study patients, complete follow-up until death was available in 230 (87%). Most patients had an adenocarcinoma as their underlying cancer (60%) and had systemic metastases (69%). Despite a median survival of 84 days (interquartile range 24-419 days), 90 patients (34%; 95% confidence interval 28%-40%) had 117 recurrent thromboembolic events, consisting of 57 cases of venous thromboembolism, 36 recurrent ischemic strokes, 13 myocardial infarctions, 10 cases of systemic embolism, and one TIA. Kaplan-Meier rates of recurrent thromboembolism were 21%, 31%, and 37% at 1, 3, and 6 months, respectively; cumulative rates of recurrent ischemic stroke were 7%, 13%, and 16%. Adenocarcinoma histology (hazard ratio 1.65, 95% confidence interval 1.02-2.68) was independently associated with recurrent thromboembolism.

CONCLUSIONS

Patients with acute ischemic stroke in the setting of active cancer (especially adenocarcinoma) face a substantial short-term risk of recurrent ischemic stroke and other types of thromboembolism.

Tracheostomy after severe ischemic stroke: a population-based study

BACKGROUND

Stroke can result in varying degrees of respiratory failure. Some patients require tracheostomy in order to facilitate weaning from mechanical ventilation, long-term airway protection, or a combination of the two. Little is known about the rate and predictors of this outcome in patients with severe stroke. We aim to determine the rate of tracheostomy after severe ischemic stroke.

METHODS

Using the Nationwide Inpatient Sample database from 2007 to 2009, patients hospitalized with ischemic stroke were identified based on validated International Classification of Diseases, 9th revision, Clinical Modification codes. Next, patients with stroke were stratified based on whether they were treated with or without decompressive craniectomy, and the rate of tracheostomy for each group was determined. A logistic regression analysis was used to identify predictors of tracheostomy after decompressive craniectomy. Survey weights were used to obtain nationally representative estimates.

RESULTS

In 1,550,000 patients discharged with ischemic stroke nationwide, the rate of tracheostomy was 1.3% (95% confidence interval [CI], 1.2-1.4%), with a 1.3% (95% CI, 1.1-1.4%) rate in patients without decompressive craniectomy and a 33% (95% CI, 26-39%) rate in the surgical treatment group. Logistic regression analysis identified pneumonia as being significantly associated with tracheostomy after decompressive craniectomy (odds ratio, 3.95; 95% CI, 1.95-6.91).

CONCLUSIONS

Tracheostomy is common after decompressive craniectomy and is strongly associated with the development of pneumonia. Given its impact on patient function and potentially modifiable associated factors, tracheostomy may warrant further study as an important patient-centered outcome among patients with stroke.

Preoperative steroid use and the risk of infectious complications after neurosurgery

BACKGROUND AND PURPOSE

The association between preoperative corticosteroid use and infectious complications after neurosurgical procedures is unclear. We aim to determine whether corticosteroids increase the risk of infectious complications after neurosurgery.

METHODS

We examined the association between preoperative corticosteroid use and postoperative infectious complications in a cohort of adults who underwent a neurosurgical procedure between 2005 and 2010 at centers participating in the National Surgical Quality Improvement Program. Corticosteroid use was defined as at least 10 days of oral or parental therapy in the 30 days prior to surgery. Our primary outcome was a composite of any infectious complications occurring within 30 days of surgery. We used propensity score analysis to examine the independent association between preoperative corticosteroid use and postoperative infections.

RESULTS

Among 26 634 neurosurgical procedures, 1228 (4.61%, 95% confidence interval [CI], 4.36-4.86) were preceded by preoperative corticosteroid use and 1469 (5.52%; 95% CI, 5.24-5.79) were followed by postoperative infections. In a propensity score analysis controlling for comorbidities, illness severity, and preexisting preoperative infections, corticosteroid use was independently associated with subsequent postoperative infections (odds ratio, 1.38; 95% CI, 1.11-1.70). Our results were unchanged in sensitivity analyses controlling for central nervous system tumors or active treatment with chemotherapy.

CONCLUSION

Our results suggest that preoperative corticosteroid use is associated with an increased risk of infectious complications after neurosurgery. These findings may aid physicians with preoperative treatment decisions and risk stratification. Future randomized trials are needed to guide preoperative use of corticosteroids in this population.

Amyloid β-Related Central Nervous System Angiitis Presenting With an Isolated Seizure

Amyloid beta-related angiitis (ABRA) of the central nervous system (CNS) is a very rare inflammatory disorder that causes destruction of CNS arteries and subsequent neuronal injury. Most patients with ABRA are old and present with cognitive dysfunction and stroke; however, some patients may present atypically. In this article, we report a 44-year-old man who presented with a first-time seizure but was otherwise neurologically intact and denied any headache. Brain MRI showed right hemispheric and bilateral medial frontal lobe hyperintensities and microhemorrhages that were most suspicious for a mass lesion. An extensive diagnostic evaluation including CSF analysis and catheter angiography was unremarkable. A brain biopsy with specific stains for amyloid surprisingly demonstrated ABRA and led to immunosuppressive treatment. The patient has remained neurologically intact and seizure-free 1 year after presentation. This case demonstrates that ABRA can occur in young patients without headache or neurologic deficits, and should be considered in patients with new-onset seizures and mass lesions. It also reinforces the need to consider a brain biopsy in patients with idiopathic brain lesions and negative non-invasive testing, as it is virtually impossible to confirm the diagnosis of ABRA otherwise.

Risk of a thrombotic event after the 6-week postpartum period

BACKGROUND

The postpartum state is associated with a substantially increased risk of thrombosis. It is uncertain to what extent this heightened risk persists beyond the conventionally defined 6-week postpartum period.

METHODS

Using claims data on all discharges from nonfederal emergency departments and acute care hospitals in California, we identified women who were hospitalized for labor and delivery between January 1, 2005, and June 30, 2010. We used validated diagnosis codes to identify a composite primary outcome of ischemic stroke, acute myocardial infarction, or venous thromboembolism. We then used conditional logistic regression to assess each patient's likelihood of a first thrombotic event during sequential 6-week periods after delivery, as compared with the corresponding 6-week period 1 year later.

RESULTS

Among the 1,687,930 women with a first recorded delivery, 1015 had a thrombotic event (248 cases of stroke, 47 cases of myocardial infarction, and 720 cases of venous thromboembolism) in the period of 1 year plus up to 24 weeks after delivery. The risk of primary thrombotic events was markedly higher within 6 weeks after delivery than in the same period 1 year later, with 411 events versus 38 events, for an absolute risk difference of 22.1 events (95% confidence interval [CI], 19.6 to 24.6) per 100,000 deliveries and an odds ratio of 10.8 (95% CI, 7.8 to 15.1). There was also a modest but significant increase in risk during the period of 7 to 12 weeks after delivery as compared with the same period 1 year later, with 95 versus 44 events, for an absolute risk difference of 3.0 events (95% CI, 1.6 to 4.5) per 100,000 deliveries and an odds ratio of 2.2 (95% CI, 1.5 to 3.1). Risks of thrombotic events were not significantly increased beyond the first 12 weeks after delivery.

CONCLUSIONS

Among patients in our study, an elevated risk of thrombosis persisted until at least 12 weeks after delivery. However, the absolute increase in risk beyond 6 weeks after delivery was low. (Funded by the National Institute of Neurological Disorders and Stroke.).

Predicting future brain tissue loss from white matter connectivity disruption in ischemic stroke

BACKGROUND AND PURPOSE

The Network Modification (NeMo) Tool uses a library of brain connectivity maps from normal subjects to quantify the amount of structural connectivity loss caused by focal brain lesions. We hypothesized that the Network Modification Tool could predict remote brain tissue loss caused by poststroke loss of connectivity.

METHODS

Baseline and follow-up MRIs (10.7±7.5 months apart) from 26 patients with acute ischemic stroke (age, 74.6±14.1 years, initial National Institutes of Health Stroke Scale, 3.1±3.1) were collected. Lesion masks derived from diffusion-weighted images were superimposed on the Network Modification Tool's connectivity maps, and regional structural connectivity losses were estimated via the Change in Connectivity (ChaCo) score (ie, the percentage of tracks connecting to a given region that pass through the lesion mask). ChaCo scores were correlated with subsequent atrophy.

RESULTS

Stroke lesions' size and location varied, but they were more frequent in the left hemisphere. ChaCo scores, generally higher in regions near stroke lesions, reflected this lateralization and heterogeneity. ChaCo scores were highest in the postcentral and precentral gyri, insula, middle cingulate, thalami, putamen, caudate nuclei, and pallidum. Moderate, significant partial correlations were found between baseline ChaCo scores and measures of subsequent tissue loss (r=0.43, P=4.6×10(-9); r=0.61, P=1.4×10(-18)), correcting for the time between scans.

CONCLUSIONS

ChaCo scores varied, but the most affected regions included those with sensorimotor, perception, learning, and memory functions. Correlations between baseline ChaCo and subsequent tissue loss suggest that the Network Modification Tool could be used to identify regions most susceptible to remote degeneration from acute infarcts.

Evaluation of computed tomography angiography plaque thickness measurements in high-grade carotid artery stenosis

BACKGROUND AND PURPOSE

Increasing evidence suggests that carotid artery imaging can identify vulnerable plaque elements that increase stroke risk. We correlated recently proposed markers, soft and hard plaque thickness measurements on axial computed tomography angiography source images, with symptomatic disease status (ipsilateral stroke or transient ischemic attack) in high-grade carotid disease.

METHODS

Soft plaque and hard plaque thickness were measured with a recently validated technique using computed tomography angiography source images in subjects with ≥70% extracranial carotid artery stenosis. Logistic regression analyses were used to assess the strength of association between soft and hard plaque thickness measurements and previous stroke or transient ischemic attack. Receiver operating characteristic analysis was also performed.

RESULTS

Compared with asymptomatic subjects, those with symptomatic carotid disease had significantly larger soft plaque and total plaque thickness measurements and smaller hard plaque thickness measurements. Each 1-mm increase in soft plaque resulted in a 2.7 times greater odds of previous stroke or transient ischemic attack. Soft plaque thickness measurements provided excellent discrimination between symptomatic and asymptomatic disease, with receiver operating characteristic analysis showing an area under the curve of 0.90. A cutoff of 3.5-mm maximum soft plaque thickness provided a sensitivity of 81%, specificity of 83%, positive predictive value of 85%, and a negative predictive value of 78%.

CONCLUSIONS

Increasing maximum soft plaque thickness measurements are strongly associated with symptomatic disease status in carotid artery stenosis. Prospective validation of these results may translate into a widely accessible stroke risk stratification tool in high-grade carotid artery atherosclerotic disease.

Abstract W P41: Predicting Future Atrophy from White Matter Connectivity Disruption in Ischemic Stroke

Background: The Network Modification (NeMo) Tool uses a library of brain connectivity maps from normal subjects to quantify the amount of structural connectivity loss caused by focal brain lesions. We hypothesized that the NeMo Tool could predict remote brain tissue loss caused by Wallerian degeneration after stroke.

Methods: Baseline and follow-up MRIs from 27 patients with acute ischemic stroke were collected (74±14 years, initial NIHSS 2±3, 5.7±2.8 months b/w scans). Diffusion-weighted image derived lesion masks were superimposed on the NeMo Tool’s connectivity maps in order to predict changes to the structural connectivity network and to investigate correlations with future atrophy. Regional connectivity losses were estimated via the Change in Connectivity (ChaCo) score, i.e. the percent of “injured” tracks going through lesions that connect to a given region. ChaCo scores and longitudinal tissue changes were calculated using a standard 116 region atlas.

Results: Lesion location and size varied greatly, but they occurred more frequently in the left hemisphere. The ChaCo scores, which were generally higher in regions near stroke lesions, reflected this heterogeneity. In general, ChaCo was higher in the left hemisphere than the right and was high in the postcentral and precentral gyri, insula, middle cingulate, thalami, putamen, caudate nuclei, and pallidum. Moderate correlations were found between ChaCo scores at baseline and measures of subsequent tissue loss (change in volume and average mean diffusivity [MD] from baseline to follow-up, see Figure 1).

Conclusions: ChaCo scores varied greatly, but the most affected regions included those with sensorimotor, perception, learning and memory functions. Moderate correlations were found between ChaCo scores at baseline and subsequent tissue loss. These results suggest that the NeMo Tool could enable more accurate prognosis, as it may identify regions most susceptible to degeneration from remote infarcts.

Abstract W MP53: Cerebrovascular Events Occurring after Hospital Discharge for Labor and Delivery

Introduction: Stroke and other cerebrovascular events (CVE) are feared complications of pregnancy. Prior studies have reported an increased risk of CVE during the postpartum period, but these studies have not reported event rates after hospital discharge for labor and delivery.

Methods: We performed a retrospective cohort study using the California State Inpatient and Emergency Department administrative databases to identify all pregnant women who went into labor at a non-federal, acute-care hospital from 2005 through 2011 and who were discharged without an ICD-9-CM diagnosis of cerebrovascular disease. The primary outcome was a CVE composite defined as any ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage, subdural hemorrhage, cerebral sinus thrombosis, pituitary apoplexy, cerebral artery dissection, or hypertensive encephalopathy, occurring after hospital discharge and prior to 6 weeks after admission for labor and delivery. Descriptive statistics were used to calculate the incidence of postpartum CVE after hospital discharge and multivariate logistic regression was used to evaluate the association between several a priori selected clinical factors and postpartum CVE.

Results: A total of 2,065,330 patients were included in this analysis. The rate of any CVE was 9.97 per 100,000 patients (95% CI 8.61-11.3). The mortality rate in patients with CVE was 7.8% (95% CI 4.1-11%). The mean age of patients with a CVE was 31.0 years as compared to 28.3 years in patients without a CVE (p<0.001). Risk factors for any CVE were eclampsia (OR 19.9, 95% CI 6.43-61.4), chronic kidney disease (OR 3.88, 95% CI 1.02-14.8), black race (OR 3.19, 95% CI 2.26-4.50), preeclampsia (OR 2.67, 95% CI 1.99-3.59), and age (OR 1.07 per year, 95% CI 1.05-1.09).

Conclusion: The incidence of postpartum CVE after hospital discharge for labor and delivery is similar to rates reported for all postpartum events in prior publications. This suggests that a substantial proportion of postpartum cerebrovascular complications occur after hospital discharge. Therefore, clinicians should be aware that postpartum women remain at risk for stroke even if they have been discharged from their initial labor and delivery hospitalization without complication.

Abstract 60: Inpatient Statin Use in Intracerebral Hemorrhage is Strongly Associated With Improved Survival

Introduction: Inpatient statin use is associated with improved outcomes after ischemic stroke. The impact of inpatient statin use after intracerebral hemorrhage (ICH) is less clear.

Methods: We measured the impact of inpatient and outpatient statin use on 30-day survival among 3,481 patients with a primary discharge diagnosis of ICH over a 10-year period at 19 hospitals in an integrated care delivery system. We used multivariate logistic regression modeling mortality, controlling for patient characteristics, and allowing an interaction between inpatient and outpatient statin use. We also used last prior treatment analysis (LPTA), an instrumental variable reflecting local geographic and temporal treatment environment, to control for potential confounding in probit models.

Results: Kaplan-Meier analysis showed significant differences in survival after ICH among statin users before and during hospitalization (n=769), statin non-users before and during hospitalization (n=1,896), and patients who underwent statin withdrawal (n=391) (see Figure). Controlling for patient characteristics including initial severity, inpatient statin use was associated with lower mortality after ICH (odds ratio [OR] = 0.40, 95% C.I. 0.25 - 63, P<0.001) and withdrawal from statins was associated with higher mortality (OR = 2.30, 95% C.I. 1.40 - 3.91, P=0.002). LPTA models confirmed the association of inpatient statins with lower mortality (OR = 0.28, 95% C.I. 0.26 - 0.32, P=0.01).

Conclusions: Inpatient statin use is associated with improved survival after ICH, particularly among patients already on a statin as an outpatient at the time of the ICH.

Abstract 216: Risk of Thrombosis Remains Elevated for 12 Weeks After Labor and Delivery

Background: The risk of arterial and venous thrombosis remains elevated during the conventionally defined 6-week postpartum period, but it is unknown whether heightened risk persists beyond this point. Given the magnitude of postpartum thrombotic risk, we hypothesized that it remains elevated beyond 6 weeks after labor and delivery.

Methods: Using administrative claims data from all nonfederal acute care EDs and hospitals in California, we compared the risk of thrombotic events during sequential 6-week periods after delivery. We used validated ICD-9-CM codes to identify women hospitalized for ischemic stroke, acute MI, PE, or DVT; in a sensitivity analysis we included a broader list of thrombosis codes, including cerebral sinus thrombosis. We compared each patient’s likelihood of labor and delivery in the 0-to-6 week period before a thrombotic event (case period) versus a 6-week period exactly 1 year prior (control period). We repeated this case-crossover analysis for the 6-to-12 week, 12-to-18 week, and 18-to-24 week periods before the thrombotic event. Odds ratios for each time period were calculated with conditional logistic regression because each patient was matched to her own control period.

Results: Of 648,148 women with a first documented thrombotic event between 2007 and 2011, 1,620 had delivered during the prior 24 weeks. Their mean age was 30 (±7) years; 16% were black and 35% Hispanic. The risk of thrombosis was markedly higher in the 0-to-6 week period after delivery (OR, 6.6; 95% CI, 5.1-8.4) versus 1 year prior. Notably, thrombotic risk remained elevated during the 6-to-12 week period after delivery (OR, 2.3; 95% CI, 1.8-3.1). The risk then essentially normalized in the 12-to-18 week period (OR, 1.2; 95% CI, 0.9-1.6) and fully resolved in the 18-to-24 week period (OR, 0.9; 95% CI, 0.7-1.2). This pattern was similar in our sensitivity analysis and when we assessed the specific endpoints of stroke, acute MI, and PE or DVT.

Conclusions: The risk of thrombosis remains elevated beyond the traditional 6-week postpartum period, and persists for at least 12 weeks after delivery. This should be considered when evaluating postpartum women with symptoms of possible thrombosis, or making recommendations about postpartum thrombosis prophylaxis or treatment.

Abstract T P163: Influenza-Like Illness is Associated With Risk of Ischemic Stroke: A Case-Crossover Analysis

Background: Acute triggers of ischemic stroke (IS) remain poorly characterized. Emerging evidence suggests infections may promote short-term pro-inflammatory, pro-coagulant states that precipitate stroke.

Objective: We hypothesized that exposure to influenza-like illness (ILI) is associated with increased risk of IS, as time intervals between events decrease.

Methods: HCUP/AHRQ administrative claims from all nonfederal hospitals in California (2009) were queried for IS, using a published ICD-9-CM surveillance algorithm, identifying 41,148 unique individuals. A patient identifier was used to link IS patients across hospitalizations with a validated algorithm for ILI using inpatient and emergency department records. For each IS case, ILI events within 15, 30, and 90-day risk periods preceding IS in 2009, were compared to the same time periods one and two calendar years prior (i.e., 2007 and 2008). A 4-day buffer period was used to ensure ILI preceded IS. Conditional logistic regression models, matched on individuals, were used to calculate odds ratios and 95% confidence intervals (OR, 95%CI) for given risk period, after adjusting for monthly prevalence and mean age of ILI hospitalizations. Effects stratified by age are also explored.

Results: Median (IQR) age of cases was 74 (62-83) years; 52.4% were female. There were more ILI during the 90-days preceding strokes in 2009 (n=439) than in the same stroke-free calendar period one year prior (n=303) and two years prior (n=81). ILI was associated with IS with decreasing magnitude of effect using windows of 15-days (adjusted OR 6.5, 95%CI, 2.2-19.7), 30-days (adjusted OR=3.7, 95%CI 1.7-8.3), and 90-days (adjusted OR=3.3, 95%CI, 1.9-5.8). The risk associated with ILI was higher among younger patients. Using the 30-day window, the association between ILI and IS was strongest among those 45-to-65-years (n=27,545, adjusted OR=2.53, 95%CI, 0.95-6.8).

Conclusion: Influenza-like illness may contribute to a heightened risk of ischemic stroke during short term periods post-infection, especially among younger patients. Presentation with influenza represents an opportunity for targeted prevention of stroke.

Oxygen extraction fraction and stroke risk in patients with carotid stenosis or occlusion: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Increased oxygen extraction fraction on PET has been considered a risk factor for stroke in patients with carotid stenosis or occlusion, though the strength of this association has recently been questioned. We performed a systematic review and meta-analysis to summarize the association between increased oxygen extraction fraction and ipsilateral stroke risk.

MATERIALS AND METHODS

A comprehensive literature search was performed. We included studies with baseline PET oxygen extraction fraction testing, ipsilateral stroke as the primary outcome, and at least 1 year of follow-up. A meta-analysis was performed by use of a random-effects model.

RESULTS

After screening 2158 studies, 7 studies with 430 total patients with mean 30-month follow-up met inclusion criteria. We found that 6 of 7 studies were amenable to meta-analysis. Although 4 of the 6 studies independently did not reach statistical significance, meta-analysis revealed a significant positive relationship between abnormal oxygen extraction fraction and future ipsilateral stroke, with a pooled OR of 6.04 (95% CI, 2.58-14.12). There was no statistically significant difference in OR in the subgroup analyses according to testing method or disease site.

CONCLUSIONS

Abnormal oxygen extraction fraction remains a powerful predictor of stroke in carotid stenosis or occlusion and is a valuable reference standard to compare and validate MR imaging-based measures of brain oxygen metabolism. However, there is a need for further evaluation of oxygen extraction fraction testing in patients with high-grade but asymptomatic carotid disease.

Abstract T P176: Readmission for Infective Endocarditis after Ischemic Stroke or Transient Ischemic Attack

Background: Guidelines recommend blood cultures for the evaluation of cerebral ischemia when infective endocarditis (IE) is the suspected cause, but given the absence of more specific guidance, providers likely have significantly varying thresholds for obtaining blood cultures in patients with cerebral ischemia. To explore the utility of blood cultures in these patients, we assessed rates of missed diagnoses of IE in patients discharged after stroke or TIA before blood culture results could have been available.

Methods: Using administrative claims data, we retrospectively identified consecutive patients discharged from all nonfederal emergency departments (ED) or hospitals in California from 2005 through 2011 with a diagnosis of ischemic stroke (defined as ICD-9-CM codes 433.x1, 434.x1, or 436 in any diagnosis code position) or TIA (ICD-9-CM code 435 in the primary diagnosis position). Our primary outcome was a subsequent hospitalization within 14 days with any diagnosis of IE (ICD-9-CM code 391.1 or 421.x in any position). Patients with a diagnosis of IE before or at the time of their first stroke or TIA were excluded. To target patients discharged without conclusive blood culture results, only patients discharged directly from the ED or within 2 days of admission were included. A subgroup analysis was performed in patients diagnosed with TIA and discharged home from the ED.

Results: Among 172,666 patients discharged with stroke or TIA, 24 were subsequently hospitalized for IE, equating to a readmission rate of 1.4 per 10,000 (95% CI, 0.8-2.0 per 10,000). Subgroup analysis of 39,019 patients diagnosed with TIA and discharged home from the ED revealed a readmission rate of 0.8 per 10,000 (95% CI, 0.1-1.6 per 10,000). Multiple logistic regression identified valvular disease (OR, 7.0; 95% CI, 2.9-17.2), chronic kidney disease (OR, 3.7; 95% CI, 1.3-10.4), and possibly drug abuse (OR, 5.0; 95% CI, 0.7-38.3) as risk factors for readmission with IE after discharge for stroke or TIA.

Conclusions: In a cohort of patients with acute cerebral ischemia discharged before blood culture results could have been available, the rate of subsequent IE was negligible. These findings argue against the liberal use of blood cultures in the routine evaluation of ischemic stroke or TIA.

Transient global amnesia and the risk of ischemic stroke

BACKGROUND AND PURPOSE

Whether transient global amnesia (TGA) represents an arterial insult that heralds ischemic stroke remains unclear. Therefore, we examined stroke risk after TGA in a population-based cohort.

METHODS

After performing chart review at our institution to validate the International Classification of Diseases, 9th Edition, Clinical Modification diagnosis code for TGA, we used administrative claims data to identify all patients discharged from nonfederal California emergency departments or acute care hospitals between 2005 and 2010 with a primary discharge diagnosis of TGA. Patients with a primary discharge diagnosis of migraine, seizure, or transient ischemic attack were included as controls. Kaplan-Meier statistics were used to calculate rates of ischemic stroke, and Cox proportional hazards analyses were used to compare stroke risk among the 4 exposure groups while controlling for traditional stroke risk factors.

RESULTS

International Classification of Diseases, 9th Edition, Clinical Modification code 437.7 had a sensitivity of 86% and a specificity of 95% for TGA. The cumulative 1-year rate of stroke was 0.54% (95% confidence interval [CI], 0.36-0.81) after TGA, 0.22% (95% CI, 0.20-0.25) after migraine, 0.90% (95% CI, 0.83-0.97) after seizure, and 4.72% (95% CI, 4.60-4.85) after transient ischemic attack. After adjustment for demographic characteristics and stroke risk factors, TGA was not associated with stroke risk when compared with migraine (hazard ratio, 0.82; 95% CI, 0.61-1.10). The likelihood of stroke after TGA was lower than after seizure (hazard ratio, 0.57; 95% CI, 0.44-0.76) or transient ischemic attack (hazard ratio, 0.27; 95% CI, 0.20-0.35).

CONCLUSIONS

Compared with patients diagnosed with migraine or seizure, patients diagnosed with TGA do not seem to face a heightened risk of stroke.

THRIVE Score Predicts Ischemic Stroke Outcomes and Thrombolytic Hemorrhage Risk in VISTA

Background and Purpose—

In previous studies, the Totaled Health Risks in Vascular Events (THRIVE) score has shown broad utility, allowing prediction of clinical outcome, death, and risk of hemorrhage after tissue-type plasminogen activator (tPA) treatment, irrespective of the type of acute stroke therapy applied to the patient.

Methods—

We used data from the Virtual International Stroke Trials Archive to further validate the THRIVE score in a large cohort of patients receiving tPA or no acute treatment, to confirm the relationship between THRIVE and hemorrhage after tPA, and to compare the THRIVE score with several other available outcome prediction scores.

Results—

The THRIVE score strongly predicts clinical outcome (odds ratio, 0.55 for good outcome [95% CI, 0.53–0.57]; P <0.001), mortality (odds ratio, 1.57 [95% confidence interval, 1.50–1.64]; P <0.001), and risk of intracerebral hemorrhage after tPA (odds ratio, 1.34 [95% confidence interval, 1.22–1.46]; P <0.001). The relationship between THRIVE score and outcome is not influenced by the independent relationship of tPA administration and outcome. In receiver operator characteristic curve analysis, the THRIVE score was superior to several other available outcome prediction scores in the prediction of clinical outcome and mortality.

Conclusions—

The THRIVE score is a simple-to-use tool to predict clinical outcome, mortality, and risk of hemorrhage after thrombolysis in patients with ischemic stroke. Despite its simplicity, the THRIVE score performs better than several other outcome prediction tools. A free Web calculator for the THRIVE score is available at http://www.thrivescore.org .

Carotid Plaque MRI and Stroke Risk

Background and Purpose—

MRI characterization of carotid plaque has been studied recently as a potential tool to predict stroke caused by carotid atherosclerosis. We performed a systematic review and meta-analysis to summarize the association of MRI-determined intraplaque hemorrhage, lipid-rich necrotic core, and thinning/rupture of the fibrous cap with subsequent ischemic events.

Methods—

We performed a comprehensive literature search evaluating the association of carotid plaque composition on MRI with ischemic outcomes. We included cohort studies examining intraplaque hemorrhage, lipid-rich necrotic core, or thinning/rupture of the fibrous cap with mean follow-up of ≥1 month and an outcome measure of ipsilateral stroke or transient ischemic attack. A meta-analysis using a random-effects model with assessment of study heterogeneity and publication bias was performed.

Results—

Of the 3436 articles screened, 9 studies with a total of 779 subjects met eligibility for systematic review. The hazard ratios for intraplaque hemorrhage, lipid-rich necrotic core, and thinning/rupture of the fibrous cap as predictors of subsequent stroke/transient ischemic attack were 4.59 (95% confidence interval, 2.91–7.24), 3.00 (95% confidence interval, 1.51–5.95), and 5.93 (95% confidence interval, 2.65–13.20), respectively. No statistically significant heterogeneity or publication bias was present in the 3 main meta-analyses performed.

Conclusions—

The presence of intraplaque hemorrhage, lipid-rich necrotic core, and thinning/rupture of the fibrous cap on MRI of carotid plaque is associated with increased risk of future stroke or transient ischemic attack in patients with carotid atherosclerotic disease. Dedicated MRI of plaque composition offers stroke risk information beyond measurement of luminal stenosis in carotid atherosclerotic disease.

Intraplaque high-intensity signal on 3D time-of-flight MR angiography is strongly associated with symptomatic carotid artery stenosis

BACKGROUND AND PURPOSE

Intraplaque hemorrhage in carotid artery atherosclerotic plaque has been shown to be a marker of risk, associated with prior and future ischemic events, and has been associated with regions of intraplaque high-intensity signal on 3D-TOF MRA. We assessed the association of intraplaque high-intensity signal determined on 3D-TOF MRA with the incidence of prior ipsilateral stroke or TIA.

MATERIALS AND METHODS

We assessed intraplaque hemorrhage by evaluating for intraplaque high-intensity signal adapting a recently validated technique on 3D-TOF source images in participants with high-grade (≥ 70%) extracranial carotid stenosis. Logistic regression analyses were used to assess the strength of association between the presence of intraplaque high-intensity signal on routine MRA sequences and prior stroke or TIA.

RESULTS

Intraplaque high-intensity signal was present in 22 (41.5%) of 53 carotid arteries studied in 51 patients. Ipsilateral ischemic events occurred in 15 (68.1%) of 22 in the intraplaque high-intensity signal-positive group (10 strokes, 5 TIAs) and in 4 (12.9%) of 31 in the intraplaque high-intensity signal-negative group (3 strokes, 1 TIA). Ischemic events occurred within the 6-month period preceding imaging in 18 (94.7%) of 19 cases. The univariate odds ratio of the association of intraplaque high-intensity signal with any prior ischemic event was 14.5 (95% CI, 3.6-57.6), and the multivariate age- and sex-adjusted odds ratio was 14.2 (95% CI, 3.3-60.5). The association remained present across 1.5 T and 3T magnet field strengths.

CONCLUSIONS

Intraplaque high-intensity signal determined from MRA sequences already in place to measure luminal stenosis is strongly associated with prior ipsilateral ischemic events. Prospective validation of these findings to predict outcome in carotid artery stenosis could provide a valuable and widely accessible stroke risk stratification tool.