Short-term prognosis after emergency department diagnosis of TIA

Early risk of stroke after a transient ischemic attack in patients with internal carotid artery disease

BACKGROUND

Transient ischemic attacks (TIAs) often herald a stroke, but little is known about the acute natural history of TIAs. Our objective was to quantify the early risk of stroke after a TIA in patients with internal carotid artery disease.

METHODS

Using patient data from the medical arm of the North American Symptomatic Carotid Endarterectomy Trial, we calculated the risk of ipsilateral stroke in the territory of the symptomatic internal carotid artery within 2 and 90 days after a first-recorded hemispheric TIA. We also studied similar outcomes among patients in the trial who had a first-recorded completed hemispheric stroke.

RESULTS

For patients with a first-recorded hemispheric TIA (n = 603), the 90-day risk of ipsilateral stroke was 20.1% (95% confidence interval [CI] 17.0%-23.2%), higher than the 2.3% risk (95% CI 1.0%-3.6%) for patients with a hemispheric stroke (n = 526). The 2-day risks were 5.5% and 0.0%, respectively. Patients with more severe stenosis of the internal carotid artery (> 70%) appeared to be at no greater risk of stroke than patients with lesser degrees of stenosis (adjusted hazard ratio 1.1, 95% CI 0.7-1.7). Infarct on brain imaging (adjusted hazard ratio 2.1, 95% CI 1.5-3.0) and the presence of intracranial major-artery disease (adjusted hazard ratio 1.9, 95% CI 1.3-2.7) doubled the early risk of stroke in patients with a hemispheric TIA.

INTERPRETATION

Patients who had a hemispheric TIA related to internal carotid artery disease had a high risk of stroke in the first few days after the TIA. Early risk of stroke was not affected by the degree of internal carotid artery stenosis.

Longitudinal risk of intracranial hemorrhage in patients with arteriovenous malformation of the brain within a defined population

BACKGROUND AND PURPOSE

Accurate estimates for risk and rates of intracranial hemorrhage (ICH) in the natural course of patients harboring brain arteriovenous malformation (BAVM) are needed to provide a quantitative basis for planning clinical trials to evaluate interventional strategies and to help guide practice management.

METHODS

We identified patients with BAVM at the Kaiser Permanente Northern California health maintenance organization and documented their clinical course. The influences of age at diagnosis, gender, race-ethnicity, ICH at presentation, venous draining pattern, and BAVM size on ICH subsequent to presentation were studied using the multivariate Cox proportional hazards model and Kaplan-Meier curves.

RESULTS

We identified 790 patients with BAVM (51% female; 63% white; mean age+/-SD at diagnosis: 38+/-19 years) between 1961 and 2001. Patients who presented with ICH experienced a higher rate of subsequent ICH than those who presented without ICH under multivariate analysis (hazard ratio, 3.6; 95% CI, 1.1 to 11.9; P<0.032). The effect was similar across race-ethnicity and gender. This difference in ICH rates was greatest in the first year (7% versus 3% per year) and converged over time. The effect of subsequent ICH on functional status was similar to that of the initial ICH.

CONCLUSIONS

Presentation with ICH was the most important predictor of future ICH, confirming previous studies. Future ICH had similar impact on functional outcome as incident ICH. Intervention to prevent ICH would be of potentially greater benefit to patients presenting with ICH, although the advantage decreases over time.

Secondary prevention of stroke: a practical guide to drug treatment

Stroke is a disease of the elderly and, as a result of the expected demographic changes in many industrialised countries, its incidence is likely to increase in the future. A first-ever stroke significantly increases the likelihood of further events; thus, secondary prevention is of major importance. Only a minority of recurrent strokes can be prevented by surgical or other invasive methods, meaning that most secondary preventive measures involve drug treatment, which has become increasingly sophisticated in recent years. Ischaemic stroke constitutes the vast majority of all strokes; effective secondary prevention depends on a variety of factors, of which the correct classification in terms of subtypes and aetiological mechanisms is a pivotal prerequisite, as is the assessment of the patient's cardiovascular risk profile. In addition to the evaluation of pathomechanisms, stratification of subtypes of brain infarction is mainly based on morphology seen with brain imaging techniques, which provides additional evidence for the presumed cause of the stroke. Inhibitors of platelet function and anticoagulants are the two major groups of antithrombotic drugs used for the secondary prevention of stroke. Antiplatelet agents are still indicated in the majority of patients after ischaemic stroke, especially if an arterial origin is presumed. In addition to aspirin (acetylsalicylic acid), the position of which as the first-line antiplatelet drug is increasingly being questioned, other compounds with antiplatelet activity have been developed and have proven effective in secondary stroke prevention, including ticlopidine, clopidogrel and dipyridamole. Anticoagulants are principally indicated after cardioembolic ischaemic stroke; however, their inherent bleeding risks render their use in many cases rather difficult, in particular for elderly patients. Patient compliance with the recommended treatment is of major importance, given the somewhat limited efficacy of antithrombotic agents in stroke prevention. Since 'real world' experience does not match the circumstances under which clinical trials are conducted, this article will also deal with problems not covered by specific studies, such as risk stratification for anticoagulant treatment and how to proceed in cases of unknown stroke aetiology. The management of major cardiovascular risk factors is the other mainstay of secondary stroke prevention. Recent evidence indicates that antihypertensive treatment may be as effective as antithrombotic drugs for secondary prevention of stroke. This still needs to be proven for the treatment of other cardiovascular risk factors, such as diabetes mellitus and hypercholesterolemia. Nevertheless, the results of recent studies investigating the effect of HMG-CoA reductase inhibitors ('statins') on cardiovascular events strongly suggest a stroke-preventive effect.

Pathophysiology and therapeutic targets for ischemic stroke

The increased risk for stroke among those who have had a previous stroke or transient ischemic attack (TIA) and the tremendous burden of disability among stroke sufferers make both primary and secondary preventative strategies imperative. An understanding of the pathophysiology of stroke and TIA can help identify appropriate therapeutic targets.

Current and future concepts in stroke prevention

Stroke is a major cause of morbidity and mortality in an aging population. The current understanding of the pathophysiology of atherosclerotic diseases, the most common cause of stroke, and the evidence for existing therapeutic interventions for the prevention of stroke are presented. Specifically, we review the evidence for antiplatelet agents, anticoagulants, antihypertensive medications, lipid-lowering agents and carotid endarterectomy for stroke prevention.

Management and outcomes of transient ischemic attacks in Ontario

BACKGROUND

Canadian data on the characteristics, management and outcomes of patients with transient ischemic attack (TIA) are lacking. We studied prospectively a cohort of consecutive patients presenting with TIA to the emergency department of 4 regional stroke centres in Ontario.

METHODS

Using data from the Ontario Stroke Registry linked with provincial administrative databases, we determined the short-term outcomes after TIA and assessed patient management in the emergency department and within 30 days after the index TIA. We compared the TIA patients with a cohort of patients who had ischemic stroke.

RESULTS

Three-quarters of the TIA patients were discharged from the emergency department. After discharge, the 30-day stroke risk was 5% (13/265) overall and 8% (13/167) among those with a first-ever TIA; the 30-day risk of stroke or death was 9% (11/127) among the TIA patients with a speech deficit and 12% (9/76) among those with a motor deficit. Half of the cases of stroke occurred within the first 2 days after the TIA. Diagnostic investigations were underused in hospital and on an outpatient basis within 30 days after the index TIA, the rates being as follows: CT scanning, 58% (211/364); carotid Doppler ultrasonography, 44% (162/364); echocardiography, 19% (70/364); cerebral angiography, 5% (19/364); and MRI, 3% (11/364). Antithrombotic therapy was not prescribed for more than one-third of the patients at discharge. Carotid endarterectomy was performed in 2% within 90 days.

INTERPRETATION

Patients in whom TIA is diagnosed in the emergency department have high immediate and short-term risks of stroke. However, their condition is underinvestigated and undertreated compared with stroke: many do not receive the minimum recommended diagnostic tests within 30 days. We need greater efforts to improve the timely delivery of care for TIA patients, along with investigation of treatments administered early after TIA to prevent stroke.

Population based study of early risk of stroke after transient ischaemic attack or minor stroke: implications for public education and organisation of services

OBJECTIVE

To estimate the very early stroke risk after a transient ischaemic attack (TIA) or minor stroke and thereby inform the planning of effective stroke prevention services.

DESIGN

Population based prospective cohort study of patients with TIA or stroke.

SETTING

Nine general practices in Oxfordshire, England, from April 2002 to April 2003.

PARTICIPANTS

All patients who had a TIA (n = 87) or minor stroke (n = 87) during the study period and who presented to medical attention.

MAIN OUTCOME MEASURES

Risk of recurrent stroke at seven days, one month, and three months after TIAs and minor strokes.

RESULTS

The estimated risk of recurrent stroke was 8.0% (95% confidence interval 2.3% to 13.7%) at seven days, 11.5% (4.8% to 18.2%) at one month, and 17.3% (9.3% to 25.3%) at three months after a TIA. The risks at these three time periods after a minor stroke were 11.5% (4.8% to 11.2%), 15.0% (7.5% to 22.5%), and 18.5% (10.3% to 26.7%).

CONCLUSIONS

The early risks of stroke after a TIA or minor stroke are much higher than commonly quoted. More research is needed to determine whether these risks can be reduced by more rapid instigation of preventive treatment.

The acute cerebrovascular event: surgical and other interventional therapies

Over the next decade, more early and aggressive treatments will become available for acute stroke. As EPs have been forced to push their skills and knowledge significantly further with the advent of time-sensitive interventions for myocardial ischemia, a similar sophistication will undoubtedly emerge in the management of acute stroke. Certain components of the neurological examination will likely assume a new significance and, as with the renewed focus on the nature of ST segment change on the ECG in ACS, there will be new attention to early imaging findings in stroke. Although it is unclear whether the balance of future advances in treatment will come from the world of neurosurgery, neurology, or interventional radiology, the EP is relatively assured to play a central role in their implementation.

Mild Neurological Symptoms Despite Middle Cerebral Artery Occlusion

BACKGROUND AND PURPOSE

Only a small percentage of stroke patients are treated with thrombolytic therapy. We sought to determine whether vessel occlusion in mild strokes represented a new target population for interventional therapy.

METHODS

We imaged 106 acute stroke patients with MRI. Patients were identified with evidence of middle cerebral artery (MCA) occlusion and mild or no stroke signs (National Institutes of Health Stroke Scale [NIHSS] <or=3). They were compared with patients with signs of stroke, NIHSS >3, and MCA occlusion.

RESULTS

We identified 5 patients with absent flow on MRA in the MCA and mild or no stroke signs (NIHSS <or=3). All 5 were functionally independent at 3 months.

CONCLUSIONS

Caution should be exercised in considering thrombolytic therapy in these patients. Quantification of perfusion imaging is required to identify "at risk" mild stroke populations.

A follow-up analysis of transient ischemic attack patients suggests unsatisfactory disease management and possible underutilization of carotid endarterectomy in Lazio, Italy

We evaluated the disease management of transient ischemic attack in patients admitted to Lazio hospitals from July 1997 to June 1998. We assessed the effects of patient characteristics including chronic comorbidities on the use of diagnostic procedures, endarterectomy, and on the risk of adverse cerebrovascular outcome or death. There were 2,608 patients in the study who were followed up over a 18- to 30-month period. Carotid surgery was performed on 1.15% of the subjects, total mortality was 34.7 per 1,000 person-years and adverse cerebrovascular outcome was observed in 38.1 per 1,000 person-years. Chronic comorbidities did affect the mortality rate and the rate of adverse outcome, but not the rate of endarterectomies. Carotid surgery was infrequently performed in study subjects. It seems that this potentially stroke-preventive treatment was not offered to suitable candidates in many instances.

The burden of coronary, cerebrovascular and peripheral arterial disease

Atherothrombosis is a potentially life-threatening generalised disease process that affects the coronary, cerebral and peripheral vasculature, with clinical manifestations including myocardial infarction, ischaemic stroke and peripheral arterial disease. Atherothrombosis represents a massive clinical and economic burden to healthcare, annually accounting for at least 22% of all deaths globally. Moreover, the prevalence of atherothrombotic disease is increasing as a result of increased longevity resulting in a larger cohort of older individuals. Stroke in particular is a major burden, and is the primary cause of adult disability, the second most important cause of dementia, and the third leading cause of death in industrialised countries. Atherothrombosis is also associated with a poor prognosis, significantly reducing life expectancy in the 60-year-old patient by 8-12 years depending on the vascular event. Moreover, this already shortened life expectancy is further and substantially reduced in patients with more than one atherothrombotic event. The economic burden of atherothrombosis is significant, particularly given its increasing prevalence, with the United States spending over US dollars 300 billion on it. There is thus a need for effective intervention to prevent or reduce mortality and morbidity. Evidence-based medicine using economics, clinical trials data, outcomes research, epidemiology and risk stratification are necessary to target treatment effectively to patients at greatest risk, in an attempt to reduce the burden of atherothrombotic disease.

Management of Atherothrombosis with Clopidogrel in High-Risk Patients with Recent Transient Ischaemic Attack or Ischaemic Stroke (MATCH): Study Design and Baseline Data

BACKGROUND

The CAPRIE study showed the superiority of clopidogrel over acetylsalicylic acid (ASA) for reducing the combined risk of major atherothrombotic events in patients with recent myocardial infarction (MI), recent ischaemic stroke (IS) or established peripheral arterial disease. The benefit of clopidogrel over ASA is amplified in high-risk patients. Proof of concept for the benefit of clopidogrel in addition to ASA in patients with coronary manifestations of atherothrombosis was provided by the CURE trial.

METHODS

MATCH is a randomized, double-blind, placebo-controlled trial that compares clopidogrel and ASA versus clopidogrel alone in high-risk patients with recently symptomatic cerebrovascular disease. Eligible patients have experienced a transient ischaemic attack (TIA) or IS within the last 3 months and have evidence of at least 1 additional risk factor within the last 3 years (prior IS, MI, stable or unstable angina pectoris, diabetes or symptomatic peripheral arterial disease). Patients were randomized to receive ASA 75 mg once daily or placebo, with both groups receiving clopidogrel 75 mg once daily as part of standard therapy. The primary end point is the composite of IS, MI, vascular death and rehospitalization for an acute ischaemic event. The duration of treatment and follow-up is 18 months for each patient.

RESULTS

Enrollment was completed in April 2002, with 7,599 patients randomized to receive the study medication. The mean age at randomization was 66 years, and the qualifying event was IS in 78.9% of patients and TIA in 21.1%. The baseline features of the study cohort indicate a population that is at a high risk for atherothrombotic recurrence.

CONCLUSION

MATCH is a major ongoing trial that will provide important data on the benefit of clopidogrel and ASA compared with clopidogrel alone for reduction of vascular ischaemic events in patients with recent TIA or IS who are at high risk of atherothrombotic event recurrence.

Head Computed Tomography Findings Predict Short-Term Stroke Risk After Transient Ischemic Attack

Background and Purpose— Current guidelines recommend the use of head CT in the evaluation of patients with transient ischemic attack (TIA), but data supporting its value are sparse.

Methods— Patients who presented to 1 of 16 emergency departments of a large Northern California health maintenance organization and received a diagnosis of TIA from November 1997 through February 1998 were enrolled and followed up for 90 days. Clinical, demographic, and outcome data were obtained from computerized databases and medical records. Physicians blinded to patient characteristics and outcomes abstracted head CT findings from radiology reports. Abstracted findings included evidence of old or new infarct, periventricular white-matter disease, cerebral atrophy, cerebral vascular calcification, and nonischemic lesions.

Results— Head CT was performed in 67% of eligible patients (n=322) diagnosed with TIA. Evidence of a new infarct was seen on head CT in 13 patients (4%). A nonischemic cause of TIA symptoms was found in 4 patients (1.2%). During follow-up, 10.9% of TIA patients experienced subsequent stroke. After adjustment for confounders, risk for stroke during follow-up was significantly higher in those with a new infarct on head CT compared with others with TIA (odds ratio, 4.06; 95% confidence interval, 1.16 to 14.14; P =0.028). Old infarction, periventricular white-matter disease, cerebral atrophy, and cerebral vascular calcification were not predictors of subsequent risk of stroke.

Conclusions— Evidence of a new infarct on head CT in patients presenting with TIA is associated with increased short-term risk for stroke. Head CT appears to have prognostic value in patients with TIA and, for this reason alone, may be justified in their evaluation.

Extracranial carotid artery stenosis

BACKGROUND

Carotid endarterectomy is the most common surgical procedure used to treat stenosis of the extracranial precerebral carotid artery. Data from several randomized controlled trials are available to help guide its use in specific patient subgroups. Carotid angioplasty with stenting is also being performed, and clinical trials comparing this procedure with carotid endarterectomy are in progress.

SUMMARY OF REPORT

For patients with symptomatic high-grade (ie, 70% to 99%) stenosis, carotid endarterectomy is associated with an overall benefit (risk ratio estimate for the combined end point of nonfatal stroke, nonfatal myocardial infarction, or death, 0.67; 95% CI, 0.54 to 0.83). The benefit is more modest for patients with less severe stenosis (ie, 50% to 69%) and may vary with specific patient characteristics. Selected patients with asymptomatic carotid stenosis may also benefit from the operation, but it needs to be performed with very low complication rates, which can be difficult to achieve in clinical practice. Several studies of angioplasty, angioplasty with stenting, and more recently angioplasty with stenting and a so-called distal protection device have also been performed. The technology involved continues to evolve rapidly, presenting a challenge for the design and conduct of clinical trials.

CONCLUSIONS

Surgical intervention for extracranial carotid stenosis remains a major potential therapeutic modality for the prevention of stroke in selected patients. Endovascular approaches continue to be evaluated in ongoing trials.

Stroke

Stroke is a major public-health burden worldwide. Prevention programmes are essential to reduce the incidence of stroke and to prevent the all but inevitable stroke epidemic, which will hit less developed countries particularly hard as their populations age and adopt lifestyles of the more developed countries. Efficient, effective, and rapid diagnosis of stroke and transient ischaemic attack is crucial. The diagnosis of the exact type and cause of stroke, which requires brain imaging as well as traditional clinical skills, is also important when it will influence management. The treatment of acute stroke, the prevention and management of the many complications of stroke, and the prevention of recurrent stroke and other serious vascular events are all improving rapidly. However, stroke management will only be most effective when delivered in the context of an organised, expert, educated, and enthusiastic stroke service that can react quickly to the needs of patients at all stages from onset to recovery.

Are patients with acutely recovered cerebral ischemia more unstable?

BACKGROUND AND PURPOSE

Recent studies suggest that the short-term risk of stroke may be greater after transient ischemic attack (TIA) than after stroke.

METHODS

We compared risks of neurological deterioration in those with and without TIA in the National Institute of Neurological Disorders and Stroke (NINDS) tissue plasminogen activator (tPA) trial, a randomized trial of intravenous tPA given within 3 hours of onset of cerebral ischemia, after excluding those with cerebral hemorrhage and those dying before 90 days of causes other than new ischemic stroke. TIA was defined as a National Institutes of Health Stroke Scale (NIHSS) score of zero at 24 hours. We chose subsequent deterioration as our outcome, defined as a worsening on the NIHSS at 90 days compared with 24 hours, so that episodes of new ischemia that may have been attributed to other causes would be included.

RESULTS

Of 498 subjects meeting entry criteria, 40 (8%) had TIA. Subsequent deterioration occurred in 30% of those with TIA and 10% of others (P=0.001, Fisher exact test). In multivariable models with adjustment for age, sex, ethnicity, 24-hour NIHSS score, tPA administration, presumed stroke subtype, and baseline systolic blood pressure, temperature, and glucose, TIA was an independent predictor of subsequent deterioration (odds ratio, 5.0; 95% CI, 2.0 to 12.5; P=0.001). Subsequent deterioration was not associated with tPA treatment, and there was no interaction between tPA administration, TIA, and subsequent deterioration. Lesser degrees of substantial acute recovery were also associated with greater risk of subsequent deterioration.

CONCLUSIONS

Patients with TIA may be a greater risk of subsequent neurological deterioration from causes other than hemorrhage. Substantial acute recovery may be an indicator of greater instability more broadly.

Early recovery after cerebral ischemia risk of subsequent neurological deterioration

Given the high short-term risk of stroke after transient ischemic attack, we hypothesized that substantial acute neurological recovery in patients presenting with cerebral ischemia would be associated with a greater risk of subsequent neurological deterioration due to recurrent cerebral ischemia. Data from the Trial of ORG10172 in Acute Stroke Treatment, a randomized trial of the heparinoid danaparoid, were analyzed to determine whether substantial acute recovery, defined as an improvement of greater than or equal to 75% on National Institutes of Health Stroke Scale (NIHSS) between baseline and 24 hours, was associated with a greater risk of subsequent deterioration, defined as a worsening on the NIHSS between day 1 and day 90. Of 1,184 subjects meeting entry criteria, 63 (5.3%) had substantial acute recovery. Subsequent deterioration was more common in those with substantial acute recovery compared with others (48 vs 33%; p = 0.028 by Fisher's exact test). In multivariable models, substantial acute recovery remained an independent predictor of subsequent deterioration (odds ratio, 3.0; 95% confidence interval, 1.7-5.2; p < 0.001). Among patients with acute cerebral ischemia, those who recover substantially within 24 hours may be at greater risk of subsequent neurological deterioration due to causes other than hemorrhage.

Incidence, risk factors and prognosis of stroke and TIA: the need for high-quality, large-scale epidemiological studies and meta-analyses

Stroke is a considerable clinical, social and economic burden. In recent clinical trials, a number of strategies have been shown to reduce the risk of stroke and transient ischaemic attack (TIA) in both primary and secondary prevention settings. Whether these treatments are leading to a significant reduction in the incidence of first and recurrent stroke in the clinic, however, remains unclear due to a paucity of high-quality epidemiological data. A similar lack of reliable epidemiological studies has undermined our understanding of the relationship between many potentially important vascular risk factors and stroke risk. Improvement in our knowledge of stroke epidemiology is a prerequisite for the planning of stroke services, the effective application of current stroke prevention strategies, the development of new strategies, and our understanding of the mechanisms of stroke. Future studies must take into account the clinical and pathological heterogeneity of TIA and stroke, and must be powered to allow subtype differences in risk factor relationships and prognosis to be determined reliably. In many cases, this will require meta-analysis of detailed individual patient data from multiple independent studies.

Very early risk of stroke after a first transient ischemic attack

BACKGROUND AND PURPOSE

The commonly quoted early risks of stroke after a first transient ischemic attack (TIA)-1% to 2% at 7 days and 2% to 4% at 1 month-are likely to be underestimates because of the delay before inclusion into previous studies and the exclusion of patients who had a stroke during this time. Therefore, it is uncertain how urgently TIA patients should be assessed. We used data from the Oxford Community Stroke Project (OCSP) to estimate the very early stroke risk after a TIA and investigated the potential effects of the delays before specialist assessment.

METHODS

All OCSP patients who had a first-ever definite TIA during the study period (n=209) were included. Three analyses were used to estimate the early stroke risk after a first TIA starting from 3 different dates: assessment by a neurologist, referral to the TIA service, and onset of first TIA.

RESULTS

The stroke risk from assessment by a neurologist was 1.9% [95% confidence interval (CI), 0.1 to 3.8] at 7 days and 4.4% (95% CI, 1.6 to 7.2) at 30 days. The 7- and 30-day stroke risks from referral were 2.4% (95% CI, 0.3 to 4.5) and 4.9% (95% CI, 1.9 to 7.8), respectively, and from onset of first-ever TIA were 8.6% (95% CI, 4.8 to 12.4) and 12.0% (95% CI, 7.6 to 16.4), respectively.

CONCLUSIONS

The early risk of stroke from date of first-ever TIA is likely to be higher than commonly quoted. Public education about the symptoms of TIA is needed so that medical attention is sought more urgently and stroke prevention strategies are implemented sooner.

Early ischemic lesion recurrence within a week after acute ischemic stroke

Previous observations suggested that multiple ischemic lesions on diffusion-weighted imaging (DWI) are common in acute stroke patients. We hypothesized that a source of these multiple lesions was the recurrence of ischemic lesions within a week after a clinically symptomatic stroke. We analyzed 99 acute ischemic stroke patients scanned within 6 hours of onset and at subsequent times within the first week. Ischemic lesion recurrence was defined as any new lesion separate from the index lesion. Recurrent lesions occurring outside initial perfusion deficit were termed 'distant lesion recurrence'. We estimated the hazard ratio (HR) of recurrence associated with clinical and imaging characteristics using log-rank test. Any lesion recurrence was found in 34%, with distant lesion recurrence in 15%, while clinical recurrence was evident in 2%. Initial multiple DWI lesions were associated with any lesion recurrence (HR, 2.83; 95% confidence interval [CI], 1.65-10.29; p = 0.002) and with distant lesion recurrence (HR, 5.99; 95% CI, 4.05-64.07; p < 0.0001). Large-artery atherosclerosis was the most frequent stroke subtype associated with any lesion recurrence (p = 0.026). These results may indicate a prolonged state of increased ischemic risk over the first week and suggest DWI as a possible surrogate measure for recurrent stroke.

Cerebrovascular cases

Five cases are presented illustrating some of the investigative and therapeutic dilemmas faced when treating patients with cerebrovascular disease in the outpatient clinic. The results of some recent major randomized controlled trials are applied to assist the decision-making process for individual patients. The investigation and management of patients with minor stroke or transient ischemic attack, and symptomatic or asymptomatic carotid stenosis are discussed. Issues raised include the role of angiography versus noninvasive imaging, carotid endarterectomy versus carotid stenting, and how to apply new evidence regarding antihypertensive and lipid-lowering therapy to patient management. The role of thrombolysis for acute stroke is discussed, and the work-up of a patient with attacks of dizziness and a patient with atypical headache are also presented.

Transient ischaemic attacks : new approaches to management

The fact that transient ischaemic attacks are a harbinger for the possible development of ischaemic stroke has been recognised for several decades. However, within the past decade, our concepts regarding transient ischaemic attacks as a distinct entity from stroke and the prognosis for transient ischaemic attack patients have been challenged. In addition, clinical trials have clarified that modern transient ischaemic attack management is more complex than in the past, with the addition of newer pharmacological options to the stroke prevention armamentarium. Recent information regarding newer antiplatelet agents is reviewed in this article, along with results of clinical trials pertaining to warfarin in stroke prevention. The evolving role of statins, ACE inhibitors and estrogen replacement is reviewed. Finally, the appropriate use of surgery following transient ischaemic attacks is outlined. Recent studies have shown that many patients will benefit from a multimodal pharmacological approach following transient cerebral ischaemia, and the potential for combination therapy is highlighted.

Diffusion-weighted MRI in evaluation of transient ischemic attack

Diffusion-weighted magnetic resonance imaging (DWI) is a sensitive diagnostic tool for detecting recent ischemic lesions in patients with transient ischemic attacks (TIAs), but the interpretation of the presence or absence of DWI abnormalities in TIA patients still remains controversial. To elucidate the pathophysiology underlying those lesions, we analyzed DWI abnormalities in patients with recent TIAs. Based on 45 consecutive patients with TIAs who underwent DWI within 10 days of onset, demographic data and clinical manifestations were analyzed in relation to the DWI abnormalities. According to the method utilized in the Oxfordshire Community Stroke Study, clinical manifestations were classified into classical lacunar syndrome and non-lacunar symptoms. Based on the vascular distributions of ischemic lesions, the DWI abnormalities were classified into small-vessel and large-vessel lesions. DWI abnormalities were detected in 14 (31%) of 45 TIA patients. Seven (50%) of 14 DWI-positive patients had occlusive vascular lesions on intracranial magnetic resonance angiography, while only 5 (16%) of 31 DWI-negative patients had occlusive lesions (P < .05). No other demographic or clinical features, including risk factor and presence of cardiac disease, differed significantly between the DWI-positive and DWI-negative patient groups. Four (46%) of 9 DWI-positive patients who had a classical lacunar syndrome also showed small-vessel lesions on DWI, whereas all 5 patients who had non-lacunar symptoms showed large-vessel lesions. We concluded that although DWI abnormalities were detected in only one third of our TIA patients, DWI abnormalities were closely related to intracranial vascular occlusive lesions. The combination of DWI and MRA was useful for detecting large-artery lesions in patients displaying a classical lacunar syndrome.

Medical prevention of stroke, 2003

Stroke is a preventable tragedy for nearly 750,000 people each year. Primary stroke prevention measures applicable to the general public include a healthy diet containing fruits, vegetables, fish, and low fat; exercise; smoking cessation; limiting alcohol to moderate use; and perhaps avoidance of stress. Screening for hypertension, cholesterol, heart disease, and carotid artery stenosiscan lead to even more effective stroke prevention in high-risk patients. Specific antihypertensive drugs such as angiotensin-converting enzyme inhibitors and angiotensin-converting enzyme receptor blockers may be especially protective against stroke. Secondary stroke prevention in patients who have already had a stroke or transient ischemic attack is even more effective in preventing more serious strokes. Measures include antihypertensive and cholesterol-lowering agents, carotid endarterectomy, anticoagulation for atrial fibrillation and other cardiac sources of embolic stroke, and antiplatelet therapy. Stroke prevention depends on the application of these well-known and widely available treatments to a large number of patients.

Epidemiological impact in the United States of a tissue-based definition of transient ischemic attack

BACKGROUND AND PURPOSE

The traditional definition of transient ischemic attack (TIA), based on an arbitrary time criterion of symptom resolution within 24 hours, is problematic because a large number of patients with traditionally defined TIAs have a relevant cerebral infarction on brain imaging. The objective of this study was to characterize the epidemiological impact of adopting a tissue-based definition of TIA.

METHODS

Estimates of the annual US incidence of traditionally defined transient ischemic attacks were abstracted from the literature. Models were then constructed for determining the frequency of brain injury in traditionally defined TIAs, derived from recent human studies of MR diffusion-weighted imaging (DWI) in transient cerebral ischemia.

RESULTS

Traditionally defined US TIA annual incidence rates ranged from 37 to 107 per 100,000 per year. Across 5 series, the raw frequency of DWI positivity in traditionally defined TIAs was 44%. Adjusting for an overrepresentation of longer-duration TIAs in MR series yielded an expected frequency of diffusion MRI positivity of 33% in unselected, traditionally defined TIAs. Applying this model to the US population in the year 2000 showed that adopting a tissue-based definition of TIA would decrease the annual number of events classified as TIAs from 179,840 to 120,493 and increase events classified as strokes from 821,181 to 880,520.

CONCLUSIONS

Adopting a tissue-based definition of transient ischemic attack would reduce estimates of the annual incidence of TIA by 33% (sensitivity analysis range, 19% to 44%) and increase estimates of the annual incidence of stroke in the United States by 7% (range, 4% to 10%).

Utility of platelet adp receptor antagonism in the emergency department: a review

Emergency physicians are often the first clinicians to evaluate patients with acute atherothrombotic events. Platelet adenosine diphosphate (ADP) receptor antagonists, by specifically and irreversibly blocking ADP-induced platelet activation and aggregation, may reduce the injury associated with this process and can prevent recurrent ischemic events. Their role in the prevention of recurrent vascular events has been well documented. Recently, the CURE Trial showed that the combination of aspirin and clopidogrel improved outcomes in patients with non-ST-segment-elevation acute coronary syndrome (ACS). Familiarity with ADP receptor antagonists and knowledge about their appropriate use is important to the emergency physician in the management of ACS and potentially in that of transient ischemic attacks (TIAs), ischemic strokes, and acute peripheral arterial obstruction. This review addresses the pathophysiology of atherothrombosis and evaluates the potential use of ADP receptor antagonists in the Emergency Department setting.

Adherence to practice guidelines for transient ischemic attacks in an emergency department

OBJECTIVE

To evaluate the investigation and treatment of patients with a diagnosis of transient ischemic attacks (TIA) in the emergency department (ED) a tertiary care teaching hospital with a neuroscience referral program.

METHODS

A chart review was conducted in the hospital. Consecutive ED charts with a diagnosis of TIA were included; each was reviewed by independent coders using a standardized data form.

RESULTS

Two hundred and ninety-three TIA charts were reviewed; the gender ratio was 1:1 with a mean age of 66 years. Most patients (75%; 95% CI: 70, 80) were evaluated by ED physicians; the remaining patients were seen directly by referral services. The median time from symptom onset to ED arrival was 29 hours and the duration of symptoms was 4.6 hours. Most patients received CT scans (81%; 95% CI: 73, 85), complete blood counts (74%; 95% CI: 68, 79), and electrocardiograms (75%; 95% CI: 70, 80) in the ED. In 16% (95% CI: 13, 22) a carotid doppler was performed and in 26% (95% CI: 21, 31) an outpatient doppler was booked. Among those who were discharged (75%; 95% CI: 70, 80), antithrombotic medications were not prescribed to 28% (95% CI: 22, 34).

CONCLUSION

Practice variation exists with respect to the investigation and treatment of TIAs in this tertiary-care teaching hospital. Carotid doppler investigation and use of anti-platelet therapy for patients with TIA are suboptimal. Clinical practice guidelines and rapid assessment TIA clinics may change these results.

Effects of the September 11th attacks on urgent and emergent medical evaluations in a Northern California managed care plan

PURPOSE

To determine whether the terrorist attacks on September 11, 2001, affected the health of persons far from the attacks, we studied rates of urgent and emergency medical evaluations among the 3 million persons enrolled in a managed care plan in Northern California.

METHODS

Using a computerized database of all urgent care and emergency department evaluations, we monitored physician diagnoses made during the 6 weeks before and after September 11, 2001, at 16 hospitals in the Kaiser Permanente Medical Care Program. Actual rates of evaluations and diagnoses were compared with expected rates based on similar periods in 1998, 1999, and 2000.

RESULTS

There were 4260 fewer urgent and emergent medical evaluations than expected during the 6 weeks beginning September 11, 2001 (-4%; 95% confidence interval [CI]: -3% to -5%; P <0.0001; N = 95,603). Emergency department visits occurred at the expected rate (-1%; 95% CI: -2% to 1%; P = 0.34), but urgent care visits were reduced (-9%; 95% CI: -8% to -11%; P <0.0001). Evaluations were particularly less frequent during the week beginning September 11 (-7%; 95% CI: -4% to -9%; P <0.0001), but a decrease persisted afterwards. Compared with expected rates, injuries (P <0.0001) and ill-defined/symptom-related diagnoses (P <0.0001) were less frequent, while gastrointestinal diagnoses (P = 0.01) were more frequent, during the 6 weeks after the attacks. Total urgent and emergent evaluations were mostly unchanged on September 11; only diagnoses associated with cardiac ischemia were more frequent (+70%; 95% CI: 10% to 163%; P = 0.02).

CONCLUSION

Total urgent and emergent medical evaluations in a California managed care plan were reduced during the 6 weeks after the September 11th attacks. These results may help in allocation of resources during national disasters.

Acute ischemic stroke: emergent evaluation and management

This article discusses stroke, the third leading cause of death and number one cause of adult disability in the United States, inflicting a devastating physical, emotional, and financial toll on its victims and their families. The last decade has seen the emergence of new treatments for acute stroke, energizing stroke care providers and spreading a sense of optimism among them. Because effective stroke treatment is extremely time-dependent, it is paramount that emergency physicians understand and excel in their critical role at the forefront of stroke management. This article outlines the emergent evaluation and management of acute ischemic stroke, emphasizing the importance of the emergency physician in acute stroke treatment.

Transient ischemic attacks: an emergency medicine approach

Recent advances in TIA research provide emergency physicians a new understanding of the disease process. Untreated or under-treated patients with TIA are at significant risk. Prompt and thorough evaluation must be undertaken to prevent devastating harm to this group of patients. This is truly a paradigm shift for many physicians, and one area in which emergency physicians lead in education and patient advocacy. The authors wish to acknowledge Dr. Stewart Wright, Dr. Alex Schneider, and Dr. Dawn Kleindorfer for their expert review, and Amy Hess for her assistance in the preparation of this manuscript.

Temporal profile of enhanced vulnerability of the postthrombotic brain to secondary embolic events

BACKGROUND AND PURPOSE

Patients with vascular or cardiac disease may experience recurrent thrombosis and embolization to the cerebral vasculature. Transient distal platelet accumulation after common carotid artery thrombosis (CCAT) leads to hemodynamic, metabolic, and molecular events that may influence the response of the postthromboembolic brain to secondary emboli. We investigated the effect of repeated embolic episodes on histopathological outcome at various time intervals using a clinically relevant model of embolic stroke.

METHODS

Six groups of rats underwent either photochemically induced CCAT followed by sham surgery or 2 episodes of CCAT separated by 10 minutes or 1, 3, 5, or 7 days. Outcome measures included routine histopathological analysis and determination of the number of infarct loci and their total volume.

RESULTS

Rats that underwent a second CCAT at 1, 3, or 5 days after the first insult had 20 to 30 times larger infarct volumes than rats in the single-CCAT group (P<0.05). In addition, rats in the 10-minute and 1-, 3-, and 5-day groups had 2 to 3 times as many infarcts as those in the single-CCAT group (P<0.05). Infarcts produced by double insults commonly extended through the neuraxis and were necrotic, edematous, and sometimes hemorrhagic.

CONCLUSIONS

A prior thromboembolic event puts the brain at risk for severe infarction after a second embolic event. These findings cannot be explained solely by a greater number of infarcts. Elucidating pathomechanisms responsible for the vulnerability of the postthromboembolic brain may provide targets for new treatment strategies to prevent the severe consequences of embolic stroke.

Potential influence of acute CT on inpatient costs in patients with ischemic stroke

RATIONALE AND OBJECTIVES

Patients presenting with ischemic brain symptoms have widely variable outcomes dependent to some degree on the pathologic basis of their stroke syndrome. The purpose of this study was to determine the cost implications of the emergency use of a computed tomographic (CT) protocol comprising unenhanced CT, head and neck CT angiography, and whole-brain CT perfusion.

MATERIALS AND METHODS

By using a retrospective patient database from a tertiary care facility and publicly available cost data, the authors derived the potential savings from the use of CT angiography. CT perfusion, or both at hospital arrival by means of a cost model. The cost of the CT angiography-CT perfusion protocol was determined from Medicare reimbursement rates and compared with that of traditional imaging protocols. Cost savings were estimated as a decrease in the length of stay for most stroke patients, whereas the most benign (lacunar) strokes were assumed to be managed in a non-acute setting. Misdiagnosis cost (erroneously not admitting a patient with nonlacunar stroke) was calculated as the cost of a severe complication. Sensitivity testing included varying the percentage of misdiagnosed patients and admitting patients with lacunar stroke.

RESULTS

The nationwide net savings that would result from the adoption of the CT angiography-CT perfusion protocol are in the $1.2 billion range (-$154 million to $2.1 billion) when patients with lacunar strokes are treated nonacutely and $1.8 billion when those patients are admitted for acute care.

CONCLUSION

The results demonstrate the potential effect of implementing a CT angiography-CT perfusion protocol. In particular, prompt CT angiography-CT perfusion imaging could have an effect on the cost of acute care in the treatment of stroke.