Babak B Navi

Weill Cornell Medical College, New York, New York, United States

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Publications (50)331.96 Total impact

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    ABSTRACT: Background and purpose: Although chronic hypertension is a well-established risk factor for stroke, little is known about stroke risk after hypertensive encephalopathy (HE), when neurologic sequelae of hypertension become evident. Therefore, we evaluated the risk of stroke after a diagnosis of HE. Methods: We identified all patients discharged from California, New York, and Florida emergency departments and acute care hospitals between 2005 and 2012 with a primary International Classification of Diseases, Ninth Edition, Clinical Modification discharge diagnosis of HE (437.2). Patients discharged with a primary diagnosis of seizure (345.x) served as negative controls, whereas patients with a primary diagnosis of transient ischemic attack (435.x) were positive controls. Our primary outcome was the composite of subsequent ischemic stroke or intracerebral hemorrhage. Kaplan-Meier survival statistics were used to calculate cumulative outcome rates, and Cox proportional hazard analysis was used to examine the association between index disease types and outcomes while adjusting for vascular risk factors. Results: We identified 8233 patients with HE, 191 091 with seizure, and 308 680 with transient ischemic attack. The 1-year cumulative rate of ischemic stroke or intracerebral hemorrhage after HE was 4.90% (95% confidence interval [CI], 4.45-5.40) when compared with 0.92% (95% CI, 0.88-0.97) after seizure and 4.49% (95% CI, 4.42-4.57) after transient ischemic attack. The risk of intracerebral hemorrhage was significantly elevated in those with HE (hazard ratio, 2.0; 95% CI, 1.7-2.5) but not in those with transient ischemic attack (hazard ratio, 1.0; 95% CI, 0.9-1.1), when compared with seizure patients. Conclusions: Patients discharged with a diagnosis of HE face a high risk of future cerebrovascular events, particularly intracerebral hemorrhage.
    No preview · Article · Jan 2016 · Stroke
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    ABSTRACT: Background: We aimed to estimate the risk of ischemic stroke after intracranial hemorrhage in patients with atrial fibrillation. Materials and methods: Using discharge data from all nonfederal acute care hospitals and emergency departments in California, Florida, and New York from 2005 to 2012, we identified patients at the time of a first-recorded encounter with a diagnosis of atrial fibrillation. Ischemic stroke and intracranial hemorrhage were identified using validated diagnosis codes. Kaplan-Meier survival statistics and Cox proportional hazard analyses were used to evaluate cumulative rates of ischemic stroke and the relationship between incident intracranial hemorrhage and subsequent stroke. Results: Among 2,084,735 patients with atrial fibrillation, 50,468 (2.4%) developed intracranial hemorrhage and 89,594 (4.3%) developed ischemic stroke during a mean follow-up period of 3.2 years. The 1-year cumulative rate of stroke was 8.1% (95% CI, 7.5-8.7%) after intracerebral hemorrhage, 3.9% (95% CI, 3.5-4.3%) after subdural hemorrhage, and 2.0% (95% CI, 2.0-2.1%) in those without intracranial hemorrhage. After adjustment for the CHA2DS2-VASc score, stroke risk was elevated after both intracerebral hemorrhage (hazard ratio [HR], 2.8; 95% CI, 2.6-2.9) and subdural hemorrhage (HR, 1.6; 95% CI, 1.5-1.7). Cumulative 1-year rates of stroke ranged from 0.9% in those with subdural hemorrhage and a CHA2DS2-VASc score of 0, to 33.3% in those with intracerebral hemorrhage and a CHA2DS2-VASc score of 9. Conclusions: In a large, heterogeneous cohort, patients with atrial fibrillation faced a substantially heightened risk of ischemic stroke after intracranial hemorrhage. The risk was most marked in those with intracerebral hemorrhage and high CHA2DS2-VASc scores.
    Full-text · Article · Dec 2015 · PLoS ONE
  • Neal S. Parikh · Babak B. Navi · Sonal Kumar · Hooman Kamel
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    ABSTRACT: Background: Liver disease is common and associated with clinical and laboratory evidence of coagulopathy. The association between liver disease and intracranial hemorrhage (ICH) remains unclear. Our aim was to assess whether liver disease increases the risk of ICH. Methods: We performed a retrospective cohort study based on administrative claims data from California, Florida, and New York acute care hospitals from 2005 through 2011. Of a random 5% sample, we included patients discharged from the emergency department or hospital after a diagnosis of liver disease and compared them to patients without liver disease. Patients with cirrhotic liver disease were additionally analyzed separately. Kaplan-Meier survival statistics were used to calculate cumulative rates of incident ICH, and Cox proportional hazard analysis was used to adjust for demographic characteristics, vascular disease, and Elixhauser comorbidities. Multiple models tested the robustness of our results. Results: Among 1,909,816 patients with a mean follow-up period of 4.1 (±1.8) years, the cumulative rate of ICH after a diagnosis of liver disease was 1.70% (95% confidence interval [CI], 1.55%-1.87%) compared to .40% (95% CI, .39%-.41%) in patients without liver disease (P <.001 by the log-rank test). Liver disease remained associated with an increased hazard of ICH after adjustment for demographic characteristics and vascular risk factors (hazard ratio [HR], 1.8; 95% CI, 1.6-2.0). This was attenuated in models additionally adjusted for general comorbidities (HR, 1.3; 95% CI, 1.2-1.5). Conclusions: There is a modest, independent association between liver disease and the risk of ICH.
    No preview · Article · Dec 2015 · Journal of stroke and cerebrovascular diseases: the official journal of National Stroke Association
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    ABSTRACT: Tracheostomy is frequently performed in patients with severe ischemic stroke, intracerebral hemorrhage, or subarachnoid hemorrhage. Little is known about readmission rates among stroke patients who undergo mechanical ventilation. We used previously validated International Classification of Diseases, Ninth Edition-Clinical Modification codes and data on all discharges from nonfederal acute care hospitals in 3 states. We compared readmission rates among mechanically ventilated patients with stroke who were discharged with or without a tracheostomy. Among 39 881 patients who underwent mechanical ventilation during the index stroke hospitalization and survived to discharge, 10 690 (26.8%; 95% confidence interval, 26.4%-27.2%) underwent tracheostomy. During a mean follow-up period of 3.4 (±2.0) years, the overall incidence rate of readmissions was 4.25 (95% confidence interval, 4.22-4.28) per 100 patients per 30 days. The rate of any readmissions within 30 days was 26.9% among patients with tracheostomy compared with 22.5% among those without a tracheostomy (absolute risk difference, 4.4%; 95% confidence interval, 3.5%-5.4%; P<0.001). After adjustment for potentially confounding variables, tracheostomy was associated with a slightly increased readmission rate (incidence rate ratio, 1.07; 95% confidence interval, 1.03-1.11). Approximately one quarter of mechanically ventilated patients with stroke who survive to discharge are readmitted to the hospital within 30 days. Readmission rates are significantly higher in patients with stroke who undergo tracheostomy, but the difference is not clinically meaningful. Thirty-day readmission rates among mechanically ventilated patients with stroke are similar to Medicare beneficiaries hospitalized with major medical diseases such as pneumonia. © 2015 American Heart Association, Inc.
    No preview · Article · Aug 2015 · Stroke
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    ABSTRACT: Stroke frequently complicates infective endocarditis (IE). However, the temporal relationship between these diseases is uncertain. We performed a retrospective study of adult patients hospitalized for IE between July 1, 2007, and June 30, 2011, at nonfederal acute care hospitals in California. Previously validated diagnosis codes were used to identify the primary composite outcome of ischemic or hemorrhagic stroke during discrete 1-month periods from 6 months before to 6 months after the diagnosis of IE. The odds of stroke in these periods were compared with the odds of stroke in the corresponding 1-month period 2 years earlier, which was considered the baseline risk of stroke. Among 17,926 patients with IE, 2,275 strokes occurred within the 12-month period surrounding the diagnosis of IE. The risk of stroke was highest in the month after diagnosis of IE (1,640 vs 17 strokes in the corresponding month 2 years prior). This equaled an absolute risk increase of 9.1% (95% confidence interval 8.6%-9.5%) and an odds ratio of 96.5 (95% confidence interval 60.1-166.0). Stroke risk was significantly increased beginning 4 months before the diagnosis of IE and lasting 5 months afterward. Similar temporal patterns were seen when ischemic and hemorrhagic strokes were considered separately. The association between IE and stroke persists for longer than previously reported. Most diagnoses of stroke and IE are made close together in time, but a period of heightened stroke risk becomes apparent several months before the diagnosis of IE and lasts for several months afterward. © 2015 American Academy of Neurology.
    No preview · Article · Jul 2015 · Neurology
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    ABSTRACT: Purpose To evaluate the cost-effectiveness of a decision-making rule based on the magnetic resonance (MR) imaging assessment of intraplaque hemorrhage (IPH) in patients with asymptomatic carotid artery stenosis. Materials and Methods Two competing stroke prevention strategies were compared: (a) an intensive medical therapy-based management strategy versus (b) an imaging-based strategy in which the subset of patients with asymptomatic carotid artery stenosis with IPH on MR images would undergo immediate carotid endarterectomy in addition to ongoing intensive medical therapy. Patients in the medical therapy-only group could undergo carotid endarterectomy only with substantial carotid artery stenosis disease progression. Lifetime quality-adjusted life years (QALYs) and costs were modeled for patients with asymptomatic carotid artery stenosis with 70%-89% and 50%-69% carotid artery stenosis at presentation. Risks of stroke and complications from carotid endarterectomy, costs, and quality of life values were estimated from published sources. Results The medical therapy-based strategy had a lower life expectancy (12.65 years vs 12.95 years), lower lifetime QALYs (9.96 years vs 10.05 years), and lower lifetime costs ($13 699 vs $15 297) when compared with the MR imaging IPH-based strategy. The incremental cost-effectiveness ratio (ICER) for the MR imaging IPH strategy compared with the medical therapy-based strategy was $16 000 per QALY by using a base-case 70-year-old patient. When using starting patient ages of 60 and 80 years, the ICERs for the MR imaging IPH strategy were $3100 per QALY and $73 000 per QALY, respectively. The ICERs for the MR imaging IPH strategy were slightly higher at all ages for 50%-69% stenosis but remained below a willingness-to-pay threshold of $100 000 per QALY for starting ages of 60 and 70 years. Conclusion MR imaging IPH can be used as a cost-effective tool to identify patients with asymptomatic carotid artery stenosis most likely to benefit from carotid endarterectomy. (©) RSNA, 2015 Online supplemental material is available for this article.
    No preview · Article · Jun 2015 · Radiology
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    ABSTRACT: Magnetic resonance imaging of carotid plaque can aid in stroke risk stratification in patients with carotid stenosis. However, the prevalence of complicated carotid plaque in patients with cryptogenic stroke is uncertain, especially as assessed by plaque imaging techniques routinely included in acute stroke magnetic resonance imaging protocols. We assessed whether the magnetic resonance angiography-defined presence of intraplaque high-intensity signal (IHIS), a marker of intraplaque hemorrhage, is associated with ipsilateral cryptogenic stroke. Cryptogenic stroke patients with magnetic resonance imaging evidence of unilateral anterior circulation infarction and without hemodynamically significant (≥50%) stenosis of the cervical carotid artery were identified from a prospective stroke registry at a tertiary-care hospital. High-risk plaque was assessed by evaluating for IHIS on routine magnetic resonance angiography source images using a validated technique. To compare the presence of IHIS on the ipsilateral versus contralateral side within individual patients, we used McNemar's test for correlated proportions. A total of 54 carotid arteries in 27 unique patients were included. A total of 6 patients (22.2%) had IHIS-positive nonstenosing carotid plaque ipsilateral to the side of ischemic stroke compared to 0 patients who had IHIS-positive carotid plaques contralateral to the side of stroke (P=0.01). Stroke severity measures, diagnostic evaluations, and prevalence of vascular risk factors were not different between the IHIS-positive and IHIS-negative groups. Our findings suggest that a proportion of strokes classified as cryptogenic may be mechanistically related to complicated, nonhemodynamically significant cervical carotid artery plaque that can easily be detected by routine magnetic resonance imaging/magnetic resonance angiography acute stroke protocols. © 2015 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.
    Preview · Article · Jun 2015 · Journal of the American Heart Association
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    ABSTRACT: To estimate the hospital revisit rate of patients diagnosed with conversion disorder (CD). Using administrative data, we identified all patients discharged from California, Florida and New York emergency departments (EDs) and acute care hospitals between 2005 and 2011 with a primary discharge diagnosis of CD. Patients discharged with a primary diagnosis of seizure or transient global amnesia (TGA) served as control groups. Our primary outcome was the rate of repeat ED visits and hospital admissions after initial presentation. Poisson regression was used to compare rates between diagnosis groups while adjusting for demographic characteristics. We identified 7946 patients discharged with a primary diagnosis of CD. During a mean follow-up of 3.0 (±1.6) years, patients with CD had a median of three (IQR, 1-9) ED or inpatient revisits, compared with 0 (IQR, 0-2) in patients with TGA and 3 (IQR, 1-7) in those with seizures. Revisit rates were 18.25 (95% CI, 18.10 to 18.40) visits per 100 patients per month in those with CD, 3.90 (95% CI, 3.84 to 3.95) in those with TGA and 17.78 (95% CI, 17.75 to 17.81) in those with seizures. As compared to CD, the incidence rate ratio for repeat ED visits or hospitalisations was 0.89 (95% CI, 0.86 to 0.93) for seizure disorder and 0.32 (95% CI 0.31 to 0.34) for TGA. CD is associated with a substantial hospital revisit rate. Our findings suggest that CD is not an acute, time-limited response to stress, but rather that CD is a manifestation of a broader pattern of chronic neuropsychiatric disease. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
    No preview · Article · Apr 2015 · Journal of neurology, neurosurgery, and psychiatry
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    ABSTRACT: The yield of echocardiography in cancer patients with acute ischemic stroke is unknown. We identified adult patients with active systemic cancer diagnosed with acute ischemic stroke at a tertiary-care cancer center from 2005 through 2009 who underwent transthoracic (TTE) or transesophageal echocardiography (TEE). Two neurologists independently reviewed all clinical data, including TTE and TEE reports, and adjudicated whether echocardiographic studies revealed a definite or possible source of stroke according to pre-defined criteria. Patients were classified as having suspected cardioembolic strokes if imaging showed embolic-appearing infarcts in more than one vascular territory. Among 220 patients with cancer and ischemic stroke who underwent echocardiography, 216 (98 %) had TTE and 37 (17 %) had TEE. TTE revealed a definite source in 15 (7 %, 95 % CI 4-10 %) patients and a possible source in 42 (19 %, 95 % CI 14-25 %), while TEE revealed a definite source in 10 (27 %, 95 % CI 12-42 %) patients and a possible source in 14 (38 %, 95 % CI 21-54 %). In 92 patients with suspected cardioembolic strokes who underwent TTE, 6 (7 %, 95 % CI 1-12 %) had a definite source, including 4 with marantic endocarditis, and 20 (22 %, 95 % CI 13-30 %) had a possible source. Twenty-one of these patients also underwent TEE, which demonstrated a definite or possible source in 16 (76 %, 95 % CI 56-96 %) patients, including marantic endocarditis in 4 (19 %). The yield of TTE for detecting marantic endocarditis and other cardiac sources of stroke in cancer patients is low, but TEE may provide a higher yield in targeted patients.
    No preview · Article · Apr 2015 · Journal of Neuro-Oncology
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    ABSTRACT: Objective: To examine the association between incident cancer and the subsequent risk of stroke. Methods: Using the Surveillance Epidemiology and End Results-Medicare linked database, we identified patients with a new primary diagnosis of breast, colorectal, lung, pancreatic, or prostate cancer from 2001 through 2007. These patients were individually matched by age, sex, race, registry, and medical comorbidities to a group of Medicare enrollees without cancer, and each pair was followed through 2009. Validated diagnosis codes were used to identify a primary outcome of stroke. Cumulative incidence rates were calculated using competing risk survival statistics. Results: Among 327,389 pairs of cancer patients and matched controls, the 3-month cumulative incidence of stroke was generally higher in patients with cancer. Cumulative incidence rates were 5.1% (95% confidence interval [CI], 4.9-5.2%) in patients with lung cancer compared to 1.2% (95% CI, 1.2-1.3%) in controls (p<0.001), 3.4% (95% CI, 3.1-3.6%) in patients with pancreatic cancer compared to 1.3% (95% CI, 1.1-1.5%) in controls (p<0.001), 3.3% (95% CI, 3.2-3.4%) in patients with colorectal cancer compared to 1.3% (95% CI, 1.2-1.4%) in controls (p<0.001), 1.5% (95% CI, 1.4-1.6%) in patients with breast cancer compared to 1.1% (95% CI, 1.0-1.2%) in controls (p<0.001), and 1.2% (95% CI, 1.1-1.3%) in patients with prostate cancer compared to 1.1% (95% CI, 1.0-1.2%) in controls (p=0.085). Excess risks attenuated over time and were generally no longer present beyond 1 year. Interpretation: Incident cancer is associated with an increased short-term risk of stroke. This risk appears highest with lung, pancreatic, and colorectal cancers. This article is protected by copyright. All rights reserved. © 2014 American Neurological Association.
    No preview · Article · Feb 2015 · Annals of Neurology
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    ABSTRACT: Purpose: To project and compare the lifetime health benefits, health care costs, and incremental cost-effectiveness of a decision rule based on assessment of cerebrovascular reserve (CVR) compared with medical therapy and immediate revascularization in asymptomatic patients with carotid artery stenosis for prevention of stroke. Materials and methods: The three strategies compared included immediate revascularization (carotid endarterectomy) and ongoing medical therapy (with antiplatelet, statin, and antihypertensive agents plus lifestyle modification), medical therapy-based treatment with revascularization only for patients who progressed, and use of a CVR-based decision rule for treatment in which patients with CVR impairment undergo immediate revascularization and all others receive medical therapy. A decision analytic model was developed to project lifetime quality-adjusted life years (QALYs) and costs for asymptomatic patients with carotid stenosis with 70%-89% carotid luminal narrowing at presentation. Risks of clinical events, costs, and quality-of-life values were estimated on the basis of those in published sources. The analysis was conducted from a health care system perspective, with health and cost outcomes discounted at 3%. Results Total costs per person and lifetime QALYs were lowest for the medical therapy-based strategy ($14 597, 9.848 QALYs), followed by CVR testing ($16 583, 9.934 QALYs) and immediate revascularization ($20 950, 9.940 QALYs). The incremental cost-effectiveness ratio for the CVR-based strategy compared with the medical therapy-based strategy was $23 000 per QALY and for the immediate revascularization versus the CVR-based strategy was $760 000 per QALY. Results: were sensitive to variations in model inputs for revascularization costs and complication risks and baseline stroke risk. Conclusion: CVR testing can be a cost-effective tool to identify asymptomatic patients with carotid stenosis who are most likely to benefit from revascularization.
    No preview · Article · Sep 2014 · Radiology
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    ABSTRACT: 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.
    Preview · Article · Jul 2014 · Stroke
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    ABSTRACT: Intravenous thrombolysis is the standard treatment for acute ischemic stroke (AIS). However, patients with cancer who have stroke are often precluded from therapy because of coagulopathy or recent surgery. Endovascular therapy may be a more suitable recanalization strategy for some patients with cancer and stroke, but no prior detailed reports documenting its use in this population exist. We present a case series from a tertiary care referral center of 2 patients with active systemic cancer who were successfully treated with endovascular therapy for AIS. Both patients had active lung cancer with excellent premorbid functional status and presented with severe AIS from left middle cerebral artery occlusions. Intravenous thrombolysis was deferred because of absolute contraindications. Mechanical embolectomy was performed instead and revascularization was achieved within 5 hours in both patients, resulting in dramatic neurological recoveries-National Institutes of Health Stroke Scale improved from 14 to 0 and from 23 to 3 from admission to discharge, respectively. In conclusion, endovascular therapy may be beneficial for select patients with cancer and AIS who are ineligible for intravenous thrombolysis. However, further studies are needed to determine the safety and efficacy of endovascular therapy in the population with cancer.
    No preview · Article · Jul 2014
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    ABSTRACT: 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.
    Preview · Article · Jun 2014 · Stroke
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    ABSTRACT: 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.
    No preview · Article · May 2014 · Neurology
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    ABSTRACT: 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.
    No preview · Article · Apr 2014
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    ABSTRACT: 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.).
    Preview · Article · Feb 2014 · New England Journal of Medicine
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    ABSTRACT: 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. 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. 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. 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.
    Full-text · Article · Feb 2014 · Stroke
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    Atul Mangla · Babak B Navi · Kelly Layton · Hooman Kamel
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    ABSTRACT: 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. 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. 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). Compared with patients diagnosed with migraine or seizure, patients diagnosed with TGA do not seem to face a heightened risk of stroke.
    Preview · Article · Dec 2013 · Stroke
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    ABSTRACT: Dizziness is a frequent reason for neuroimaging and neurological consultation, but little is known about the utility of either practice. We sought to characterize the patterns and yield of neuroimaging and neurological consultation for dizziness in the emergency department (ED). We retrospectively identified consecutive adults presenting to an academic ED from 2007 to 2009, with a primary complaint of dizziness, vertigo, or imbalance. Neurologists reviewed medical records to determine clinical characteristics, whether a neuroimaging study (head computed tomography [CT] or brain magnetic resonance imaging [MRI]) or neurology consultation was obtained in the ED, and to identify relevant findings on neuroimaging studies. Two neurologists assigned a final diagnosis for the cause of dizziness. Logistic regression was used to evaluate bivariate and multivariate predictors of neuroimaging and consultation. Of 907 dizzy patients (mean age 59 years; 58% women), 321 (35%) had a neuroimaging study (28% CT, 11% MRI, and 4% both) and 180 (20%) had neurological consultation. Serious neurological disease was ultimately diagnosed in 13% of patients with neuroimaging and 21% of patients with neurological consultation, compared to 5% of the overall cohort. Headache and focal neurological deficits were associated with both neuroimaging and neurological consultation, while age ≥60 years and prior stroke predicted neuroimaging but not consultation, and positional symptoms predicted consultation but not neuroimaging. In a tertiary care ED, neuroimaging and neurological consultation were frequently utilized to evaluate dizzy patients, and their diagnostic yield was substantial.
    Full-text · Article · Aug 2013

Publication Stats

472 Citations
331.96 Total Impact Points

Institutions

  • 2008-2016
    • Weill Cornell Medical College
      • • Division of Neurobiology
      • • Department of Neurology and Neuroscience
      New York, New York, United States
  • 2015
    • Columbia University
      New York, New York, United States
  • 2009-2015
    • Memorial Sloan-Kettering Cancer Center
      • Department of Neurology
      New York, New York, United States
  • 2011-2012
    • University of California, San Francisco
      • Department of Neurology
      San Francisco, California, United States
  • 2010
    • Cornell University
      Итак, New York, United States