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

[Carotid stenosis: is the distinction between "symptomatic" and "asymptomatic" obsolete?]

Carotid stenosis is common, especially among patients with vascular risk factors. The usual distinction between "symptomatic" and "asymptomatic" corresponds to older studies on the surgical vs. conservative treatment and to newer studies on interventional treatment (angioplasty with/without stent vs. surgery). However, both forms only describe different stages of activity of the same disease. They are markers of a systemic atherosclerosis, which results in a high risk of cardiovascular events in particular. All patients with carotid stenosis profit from regular clinical and duplexsonographic follow-up-studies of the brain arteries, cardiovascular assessment and good control of all vascular risk factors. Patients with carotid stenosis may profit from carotid intervention, if this takes place shortly after onset of associated cerebral ischemia and/or if there is a favorable benefit-risk ratio.

Rapid evaluation after high-risk TIA is associated with lower stroke risk

BACKGROUND

Current 'standard of care' for patients presenting with a 'high-risk' TIA varies, with use of several outpatient and inpatient approaches. We describe the clinical outcomes and costs for high risk TIA patients who received care in a 'rapid evaluation unit', and compare these to a historical 'high-risk' cohort.

METHODS

The study cohort was comprised of patients with TIA admitted to a 'rapid evaluation unit' during the period March 2002 to April 2003. The comparison cohort was established by screening Calgary Health Region ER discharge records to identify all patients presenting with a diagnosis of TIA during the year 2000. A 'high-risk standard care cohort' was then identified based on the clinical admission criteria used to select patients for the rapid evaluation unit. Outcomes (stroke within 90 days, death) and costs were identified using chart review and provincial administrative data.

RESULTS

The early risk of stroke in the high risk standard care group (392 patients) was 9.7%, compared to 4.7% in the rapid evaluation cohort (189 patients) (p = 0.05). Median 1-year costs post TIA were CAN $8360 for patients in the rapid evaluation cohort, compared with CAN $4820 for patients in the high risk standard care group (p < 0.001).

CONCLUSIONS

The risk of early stroke was lower for patients in the rapid evaluation cohort compared to the high risk standard care cohort, suggesting that the use of rapid evaluation programs in patients with TIA at high risk of stroke may be beneficial, but incur greater costs over the course of the first year.

Urgency of Carotid Endarterectomy for Secondary Stroke Prevention

Background and Purpose— The benefit of carotid endarterectomy for preventing recurrent stroke is maximal when surgery is performed within 2 weeks after ischemic stroke or transient ischemic attack; the benefit is reduced when surgery is delayed >2 weeks and essentially lost if delayed >3 months. Guidelines recommend endarterectomy within 2 weeks poststroke/transient ischemic attack for patients with symptomatic carotid stenosis. This study examined time to endarterectomy at designated stroke centers as a measure of evidence-based best practices for stroke prevention.

Methods— From the Registry of the Canadian Stroke Network, we identified all consecutive patients presenting with acute ischemic stroke or transient ischemic attack at 12 provincial stroke centers (Ontario, Canada, 2003 to 2006) and selected those with unilateral symptomatic carotid stenosis of moderate (50% to 69%) or severe (70% to 99%) degree. Using linkages to administrative databases, we identified patients who underwent carotid endarterectomy within 6 months after the symptomatic event and calculated the time intervals between the index event and surgery. We compared the timing of surgery according to age, sex, degree of stenosis, index event, geographic region, and year. Logistic regression assessed variables associated with early surgery.

Results— One hundred five patients underwent endarterectomy for unilateral symptomatic carotid stenosis (50% to 99%) within 6 months of the index event. The median time from index event to surgery was 30 days (interquartile range, 10 to 81). Only one third (38 of 105) received endarterectomy within the recommended 2-week target timeframe, and in one fourth (26 of 105), surgery was delayed >3 months. Surgery within 2 weeks was more likely if the index event was a transient ischemic attack rather than a stroke. Access to early endarterectomy varied markedly between hospitals across the province and improved over time from 2003 to 2006.

Conclusions— In this hospital-based cohort, the majority of patients undergoing carotid endarterectomy after a transient ischemic attack or stroke had surgery delayed well beyond the period of maximum effectiveness. To enhance secondary stroke prevention, greater efforts are needed to minimize delays to diagnosis and surgical treatment for patients with symptomatic carotid stenosis.

Transcranial Doppler ultrasonography predicts cardiovascular events after TIA

Background

Transient ischemic attack (TIA) patients are at high vascular risk. We assessed the value of extracranial (ECD) and transcranial (TCD) Doppler and duplex ultrasonography to predict clinical outcome after TIA.

Methods

176 consecutive TIA patients admitted to the Stroke Unit were recruited in the study. All patients received diffusion-weighted imaging, standardized ECD and TCD. At a median follow-up of 27 months, new vascular events were recorded.

Results

22 (13.8%) patients experienced an ischemic stroke or TIA, 5 (3.1%) a myocardial infarction or acute coronary syndrome, and 5 (3.1%) underwent arterial revascularization. ECD revealed extracranial ≥ 50% stenosis or occlusions in 34 (19.3%) patients, TCD showed intracranial stenosis in 15 (9.2%) and collateral flow patterns due to extracranial stenosis in 5 (3.1%) cases. Multivariate analysis identified these abnormal ECD and TCD findings as predictors of new cerebral ischemic events (ECD: hazard ratio (HR) 4.30, 95% confidence interval (CI) 1.75 to 10.57, P = 0.01; TCD: HR 4.73, 95% CI 1.86 to 12.04, P = 0.01). Abnormal TCD findings were also predictive of cardiovascular ischemic events (HR 18.51, 95% CI 3.49 to 98.24, P = 0.001).

Conclusion

TIA patients with abnormal TCD findings are at high risk to develop further cerebral and cardiovascular ischemic events.

Imaging of the carotid arteries: the role of duplex ultrasonography, magnetic resonance arteriography, and computerized tomographic arteriography

Stenosis of the internal carotid artery represents a major cause of stroke, with atherosclerosis representing the major pathophysiology of this stenosis. It is estimated that over 700,000 Americans suffer a stroke annually. A prompt and accurate diagnosis of carotid artery disease is critical when planning a therapeutic strategy. Physical examination is inaccurate in determining the presence and severity of carotid artery disease. Therefore, reliable imaging tests which offer little risk to the patient are required.

An improved scoring system for identifying patients at high early risk of stroke and functional impairment after an acute transient ischemic attack or minor stroke

BACKGROUND

Risk of a subsequent stroke following an acute transient ischemic attack (TIA) or minor stroke is high. The ABCD(2) tool was proposed as a method to triage these patients using five clinical factors. Modern imaging of the brain was not included. The present study quantified the added value of magnetic resonance imaging (MRI) factors to the ABCD(2) tool.

METHODS

Patients with TIA or minor stroke were examined within 12 h and had a brain MRI within 24 h of symptom onset. Primary outcomes were recurrent stroke and functional impairment at 90 days. A new tool, ABCD(2)+MRI, was created by adding diffusion-weighted imaging lesion and vessel occlusion status to the ABCD(2) tool. The predictive accuracy of both tools was quantified by the area under the curve (AUC).

RESULTS

One hundred and eighty patients were enrolled and 11.1% had a recurrent stroke within 90 days. The predictive accuracy of the ABCD(2)+MRI was significantly higher than ABCD(2) (AUC of 0.88 vs. 0.78, P=0.01). Those with a high score (7-9) had a 90-day recurrent stroke risk of 32.1%, moderate score (5-6) risk of 5.4%, and low score (0-4) risk of 0.0%. The ABCD(2) tool did not predict risk of functional impairment at 90 days (P=0.33), unlike the ABCD(2)+MRI (P=0.02): high score (22.9%), moderate (7.5%), low (7.7%).

CONCLUSIONS

Risk of recurrent stroke and functional impairment after a TIA or minor stroke can be accurately predicted by a scoring system that utilizes both clinical and MRI information. The ABCD(2)+MRI score is simple and its components are commonly available during the time of admission.

Clinical- and imaging-based prediction of stroke risk after transient ischemic attack: the CIP model

BACKGROUND AND PURPOSE

Predictive instruments based on clinical features for early stroke risk after transient ischemic attack suffer from limited specificity. We sought to combine imaging and clinical features to improve predictions for 7-day stroke risk after transient ischemic attack.

METHODS

We studied 601 consecutive patients with transient ischemic attack who had MRI within 24 hours of symptom onset. A logistic regression model was developed using stroke within 7 days as the response criterion and diffusion-weighted imaging findings and dichotomized ABCD(2) score (ABCD(2) >/=4) as covariates.

RESULTS

Subsequent stroke occurred in 25 patients (5.2%). Dichotomized ABCD(2) score and acute infarct on diffusion-weighted imaging were each independent predictors of stroke risk. The 7-day risk was 0.0% with no predictor, 2.0% with ABCD(2) score >/=4 alone, 4.9% with acute infarct on diffusion-weighted imaging alone, and 14.9% with both predictors (an automated calculator is available at http://cip.martinos.org). Adding imaging increased the area under the receiver operating characteristic curve from 0.66 (95% CI, 0.57 to 0.76) using the ABCD(2) score to 0.81 (95% CI, 0.74 to 0.88; P=0.003). The sensitivity of 80% on the receiver operating characteristic curve corresponded to a specificity of 73% for the CIP model and 47% for the ABCD(2) score.

CONCLUSIONS

Combining acute imaging findings with clinical transient ischemic attack features causes a dramatic boost in the accuracy of predictions with clinical features alone for early risk of stroke after transient ischemic attack. If validated in relevant clinical settings, risk stratification by the CIP model may assist in early implementation of therapeutic measures and effective use of hospital resources.

Transient ischemic attack: diagnostic evaluation

A transient ischemic attack portends significant risk of a stroke. Consequently, the diagnostic evaluation in the emergency department is focused on identifying high-risk causes so that preventive strategies can be implemented. The evaluation consists of a facilitated evaluation of the patient's metabolic, cardiac, and neurovascular systems. At a minimum, the following tests are recommended: fingerstick glucose level, electrolyte levels, CBC count, urinalysis, and coagulation studies; noncontrast computed tomography (CT) of the head; electrocardiography; and continuous telemetry monitoring. Vascular imaging studies, such as carotid ultrasonography, CT angiography, or magnetic resonance angiography, should be performed on an urgent basis and prioritized according to the patient's risk stratification for disease. Consideration should be given for echocardiography if no large vessel abnormality is identified.

Transient ischemic attack: risk stratification and treatment

A major challenge facing the physician evaluating patients with transient ischemic attack is determining which patients are at highest short-term risk of stroke. A number of stratification schemes have been recently developed incorporating easily obtainable clinical information about the individual patient. Further, emerging data suggest a role for brain and vascular imaging in risk stratification. Many aspects of acute management of transient ischemic attack, such as which patients should be hospitalized and choice of acute antithrombotic therapy, remain controversial because of a lack of evidence from controlled trials. For longer-term prevention, there is much firmer evidence from multiple large randomized trials, and these data are reviewed in this article.

Recurrent events in transient ischemic attack and minor stroke: what events are happening and to which patients?

BACKGROUND AND PURPOSE

The risk of a recurrent stroke after transient ischemic attack (TIA) or minor stroke is high. Clinical trials are needed to assess acute treatment options in these patients. We sought to evaluate the type of recurrent events and to identify which subsets of patients are at risk for recurrent events.

METHODS

One hundred and eighty patients with TIA or minor stroke were examined within 12 hours and underwent brain MRI within 24 hours. Any neurological deterioration was recorded, and a combination of clinical and MRI factors were used to create a combined event classification. Subgroups of patients analyzed included classical TIA, patients with NIHSS=0, and patients with NIHSS >0 in ED.

RESULTS

Overall there were 38 events in 36 patients (20% event rate); 20 were symptomatic and 18 were silent (only evident because of the follow up MRI). 18/20 (90%) symptomatic events were associated with progression of presenting symptoms, compared to 2/20 (10%) with a clear recurrent stroke distinct from the original event. We found a low risk of recurrent stroke among classical definition TIA patients (1.1%). Patients with an NIHSS=0 in the ED, had an intermediate event rate (6.6%) between TIA (classical - 1.1%) and NIHSS >0 (14.4%; chi(2) test for trend, P=0.02). All clinical categories of patient (TIA, stroke, NIHSS=0) accumulated silent lesions on MRI.

CONCLUSIONS

Most events were classified as stroke progression or infarct growth rather than a recurrent stroke. A low risk of recurrence was found in patients with classical TIA and those with no neurological deficits on initial assessment.

Enhanced expression of Lp-PLA2 and lysophosphatidylcholine in symptomatic carotid atherosclerotic plaques

BACKGROUND AND PURPOSE

Circulating lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) has emerged as a novel biomarker for cardiovascular diseases. However, the correlation between the plaque expression of Lp-PLA(2) and plaque oxidative stress, inflammation, and stability as well as the clinical presentation remains poorly defined, especially for cerebrovascular disease. Therefore, this study was performed to test the hypothesis that Lp-PLA(2) expression is higher in symptomatic than in asymptomatic carotid plaques of patients undergoing carotid endarterectomy.

METHODS

The expression of Lp-PLA(2) in 167 carotid artery plaques was determined by immunoblotting and immunostaining. Plaque oxidative stress, inflammation, and stability were quantified by NAD(P)H oxidase p67phox and MMP-2 immunoblotting, oxidized LDL (oxLDL) immunoreactivity, macrophage and Sirius red collagen staining. Lysophosphatidylcholine 16:0 (lysoPC) concentration was measured in 55 plaques using liquid chromatography tandem mass spectrometry.

RESULTS

Lp-PLA(2) expression was significantly higher in plaques of symptomatic patients than asymptomatic patients (1.66+/-0.19 versus 1.14+/-0.10, P<0.05) and localized mainly to shoulder and necrotic lipid core areas in colocalization with oxLDL and macrophage content. Similarly, Lp-PLA(2) expression was related to collagen content, which was lower in plaques from symptomatic patients than in plaques from asymptomatic patients (9.1+/-2.2 versus 18.5+/-1.7% of staining/field, P<0.001). LysoPC plaque concentration was significantly higher in plaques of symptomatic than asymptomatic patients (437.0+/-57.91 versus 228.84+/-37.00 mmol/L, P<0.05).

CONCLUSIONS

Symptomatic carotid artery plaques are characterized by increased levels of Lp-PLA(2) and its product lysoPC in correlation with markers of tissue oxidative stress, inflammation, and instability. These findings strongly support a role for Lp-PLA2 in the pathophysiology and clinical presentation of cerebrovascular disease.

Fast assessment of stroke and transient ischaemic attack to prevent early recurrence (FASTER): a randomised controlled pilot trial

BACKGROUND

Patients with transient ischaemic attack (TIA) or minor stroke are at high immediate risk of stroke. The optimum early treatment options for these patients are not known.

METHODS

Within 24 h of symptom onset, we randomly assigned, in a factorial design, 392 patients with TIA or minor stroke to clopidogrel (300 mg loading dose then 75 mg daily; 198 patients) or placebo (194 patients), and simvastatin (40 mg daily; 199 patients) or placebo (193 patients). All patients were also given aspirin and were followed for 90 days. Descriptive analyses were done by intention to treat. The primary outcome was total stroke (ischaemic and haemorrhagic) within 90 days. Safety outcomes included haemorrhage related to clopidogrel and myositis related to simvastatin. This study is registered as an International Standard Randomised Controlled Trial (number 35624812) and with ClinicalTrials.gov (NCT00109382).

FINDINGS

The median time to stroke outcome was 1 day (range 0-62 days). The trial was stopped early due to a failure to recruit patients at the prespecified minimum enrolment rate because of increased use of statins. 14 (7.1%) patients on clopidogrel had a stroke within 90 days compared with 21 (10.8%) patients on placebo (risk ratio 0.7 [95% CI 0.3-1.2]; absolute risk reduction -3.8% [95% CI -9.4 to 1.9]; p=0.19). 21 (10.6%) patients on simvastatin had a stroke within 90 days compared with 14 (7.3%) patients on placebo (risk ratio 1.3 [0.7-2.4]; absolute risk increase 3.3% [-2.3 to 8.9]; p=0.25). The interaction between clopidogrel and simvastatin was not significant (p=0.64). Two patients on clopidogrel had intracranial haemorrhage compared with none on placebo (absolute risk increase 1.0% [-0.4 to 2.4]; p=0.5). There was no difference between groups for the simvastatin safety outcomes.

INTERPRETATION

Immediately after TIA or minor stroke, patients are at high risk of stroke, which might be reduced by using clopidogrel in addition to aspirin. The haemorrhagic risks of the combination of aspirin and clopidogrel do not seem to offset this potential benefit. We were unable to provide evidence of benefit of simvastatin in this setting. This aggressive prevention approach merits further study.

Prevention of secondary stroke and transient ischaemic attack with antiplatelet therapy: the role of the primary care physician [corrected]

BACKGROUND

Stroke risk is heightened among patients who have had a primary stroke or transient ischaemic attack (TIA). The primary care physician is in the best position to monitor these patients for stroke recurrence. Because stroke recurrence can occur shortly after the primary event, guidelines recommend initiating antiplatelet therapy as soon as possible. Aspirin, with or without extended-release dipyridamole (ER-DP), and clopidogrel are options for such patients. Low-dose aspirin (75-150 mg/day) has the same efficacy as higher doses but with less gastrointestinal bleeding. Clopidogrel remains an option for prevention of secondary events and may benefit patients with symptomatic atherothrombosis, but its combined use with aspirin can harm patients with multiple risk factors and no history of symptomatic cerebrovascular, cardiovascular or peripheral vascular disease.

RESULTS

Low dose aspirin is effective in secondary stroke prevention. Trials assessing aspirin plus ER-DP have shown that the combination is more effective than aspirin monotherapy in preventing stroke, with efficacy increasing among higher risk patients, notably those with prior stroke/TIA. Clopidogrel does not appear to have as much advantage over aspirin in secondary stroke prevention as aspirin plus ER-DP. Smoking cessation and cholesterol, blood glucose and blood pressure control are also important concerns in preventing recurrent stroke. In choosing pharmacological therapy, the physician must consider the individual patient's risk factors and tolerance, as well as other issues, such as use of aspirin among patients with ulcers.

CONCLUSION

Antiplatelet therapy is effective in secondary stroke prevention. Low dose aspirin can be used first-line, but aspirin plus ER-DP improves efficacy. Clopidogrel is another option in secondary stroke prevention, especially for aspirin-intolerant patients, but it appears to have less advantage over aspirin than aspirin plus ER-DP, and its combined use with aspirin has only marginally better efficacy and increased bleeding risk.

Current management of transient ischemic attack

Transient ischemic attack (TIA) is a precursor to ischemic stroke. At least half of patients with TIA have a new, small ischemic lesion demonstrable on magnetic resonance imaging using a diffusion weighted sequence. The risk of subsequent major stroke is 10-20% in the next 3 months with much of that risk front-loaded in the first week. Strategies to identify and treat high-risk patients need to be defined. The optimal treatment approach and the timing of interventions, both medical and surgical, remains unknown. In general, aspirin is the first line of treatment to prevent further stroke. Other antiplatelet agents such as clopidogrel alone or in combination with aspirin and the combination aspirin/extended-release dipyridamole may be administered. Endarterectomy or carotid stenting is of great benefit to patients with TIA secondary to stenosis in the extracranial carotid artery.

Going High with Preexisting Neurological Conditions

This review presents the potential impact of high altitude exposure on preexisting neurological conditions in patients usually living at low altitude. The neurological conditions include permanent and transient ischemia of the brain, occlusive cerebral artery disease, cerebral venous thrombosis, intracranial hemorrhage and vascular malformations, multiple sclerosis, intracranial space-occupying lesions, dementia, extrapyramidal disorders, migraine and other headaches, and epileptic seizures. New developments in diagnostic work-up and treatment of preexisting neurological conditions are also mentioned where applicable. For each neurological disorder, the authors developed absolute and relative contraindications for a trip to high altitude. These recommendations are not based on the results of controlled randomized trials, but mainly on case reports, pathophysiological considerations, and extrapolations from the low altitude situation.

Cognitive dysfunction in 16 patients with carotid stenosis: detailed neuropsychological findings

Background

Impairment of cognitive function is often present in patients with carotid artery stenosis but the details of this dysfunction have rarely been reported. Our purpose was to elucidate the cognitive dysfunction in patients with unilateral severe carotid stenosis using comprehensive neuropsychological testing, and also to identify the specific underlying clinical and radiological factors.

Methods

We analyzed the results of neuropsychological testing, the clinical history, and MR findings in 16 consecutive patients with angiographically proven severe (70-99%) stenosis of the extra cranial internal carotid artery (ICA). Cognitive functions were examined using the Seoul Neuropsychological Screening Battery and the Neglect Battery. We excluded patients with cortical infarction and those with contra lateral ICA occlusion or severe stenosis.

Results

Our comprehensive neuropsychological testing revealed obvious cognitive deficits in all patients with unilateral severe ICA stenosis, the most common being frontal executive impairment. The mean cognitive score on the memory test was also significantly lower in patients with symptomatic ICA stenosis than in asymptomatic patients (29.33±10.98, mean±SD, p < 0.05). The total score on the global cognitive test was significantly lower in patients with an ischemic lesion on MRI than in no lesion patients (113.23±34.78, p < 0.05). The presence of symptoms related to the ICA stenosis was related to cognitive dysfunction even when there were no ischemic lesions on MRI. SPECT revealed ipsilateral cortical hypoperfusion in 9 of 12 patients (75%).

Conclusions

Cognitive deficits are common in patients with unilateral severe ICA stenosis. Our findings suggest that an additional mechanism beyond the structural lesion such as chronic hypoperfusion may affect cognitive function in patients with high-grade ICA stenosis.

[Carotid Stenting in France after the EVA 3S and SPACE publications]

Angioplasty of stenoses of the carotid bifurcation is a revascularization procedure that is used successfully in many patients. With more than 10 years of experience now, the feasibility of carotid stenting has been demonstrated. Its distribution is highly variable depending on the country, with a mean penetration rate in Europe of 15% of the number of carotid revascularizations. However, the complication rate is highly variable from one series to another and depends on the type of patient treated and the operator's learning curve. The results of the first two randomized studies comparing endarterectomy and carotid stenting, EVA 3S in France and SPACE in Germany, have just been published. The conclusions of these studies only relate to symptomatic patients, who make up a small proportion of revascularized patients. At 30 days, the French study concluded that surgery was better, and the German study showed no advantage to stenting. The analysis of these results compared to other publications should make it possible to best define the current indications for carotid stenting.

Ausencia de utilidad de la escala clínica ABCD en el riesgo de infarto cerebral precoz en pacientes con accidente isquémico transitorio

BACKGROUND AND OBJECTIVE

Recently a clinical score (ABCD) to identify individuals at high seven-day risk of stroke after transient ischemic attack (TIA) was proposed. The aim of this study was to test this clinical model.

PATIENTS AND METHOD

We validated the ABCD score (age > or = 65 years = 1; hypertension = 1; unilateral weakness = 2, speech disturbance without weakness = 1, duration of symptoms in minutes > or = 60 = 2; 10-59 = 1; < 10 = 0) in 325 consecutive TIA patients. Clinical data, symptoms duration, CT scan, and ultrasonographic (carotid and transcranial) findings were collected. Seven-day risk of stroke was recorded.

RESULTS

A total of 16 (4.9%) patients had a stroke recurrence within the first seven days after symptoms onset. Six out of 16 (37.5%) strokes occurred in 115 (35.4%) patients with a score of 5 or greater, while the 7-day risk was 4.8% (95% CI 2.04-7.56) in 210 (63.5%) patients with a score less than 5. In cox proportional hazards multivariate analyses only large-artery occlusive disease remained an independent predictor of stroke recurrence [hazard ratio = 5.66 (95% CI 2.06-15.57; p = 0.001)].

CONCLUSIONS

Clinical data are not enough to identify patients at higher risk. The combination of clinical, radiological and vascular information may improve the predictive accuracy of stroke recurrence risk. The routine use of combined carotid/transcranial ultrasound testing performed early will be useful for identifying high risk individuals in order to plan urgent aggressive prevention therapies.

Time is brain!

Carotid endarterectomy (CEA) is a proven treatment in the prevention of stroke, but its overall effectiveness is reduced by excessive delays from symptom to surgery. Specifically, delaying surgery in symptomatic patients with 50-99% NASCET stenoses (70-99% ECST) for >12 weeks prevents only eight strokes per 1000 CEAs in the long term. This is a very depressing observation as the 2004 Sentinel Audit observed that only 50% of stroke patients in the UK will have undergone a Duplex scan by 12 weeks. Excessive delays prior to surgery not only undermine professional confidence in the role of CEA, but they effectively mean that while every patient is exposed to the risks of surgery, many may gain little in the way of long-term stroke prevention. Many of the issues debated in this review will only be resolved by a paradigm shift in political emphasis, but surgeons too have a responsibility to recognise and correct important deficiencies within their own practice.

Prevention of stroke and dementia by statin therapy: Experimental and clinical evidence of their pleiotropic effects

Stroke and dementia are major causes of disability in most countries. Epidemiological studies have demonstrated that statins (3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors) are likely to reduce the risk for developing these formidable disorders. The favorable outcomes in statin users may be attributable to not only cholesterol-dependent actions, but also various cholesterol-independent actions called "pleiotropic effects." Several clinical trials have suggested that statins decrease the incidence of stroke, especially ischemic stroke. Statins improve endothelial function, inhibit platelet activation, reduce blood coagulability, and suppress inflammatory reactions, all of which may contribute to the beneficial effects of the therapy. Statins also reduce the risk of vasospasm caused by subarachnoid hemorrhage (SAH). In addition, statins might inhibit the development and progression of Alzheimer's disease (AD), the dominant type of dementia in most industrialized countries, upstream of the amyloid cascade. In vitro studies have shown that statins modulate the metabolism of the beta-amyloid precursor protein (APP) and reduce the extracellular level of its proteolytic product, amyloid-beta (Abeta). The aggregated Abeta is cytotoxic, leading to formation of neurofibrillary tangles and neuronal loss in the brain. Inflammatory processes are active in AD and may contribute significantly to AD pathology. We review the experimental background regarding the pleiotropic effects of statins and summarize clinical trials that examined the preventative effects of statin therapy on stroke and dementia. We include current trials in which statin therapy is initiated within 24 hr of onset of acute ischemic stroke.

Differential risks of subsequent vascular events for transient ischaemic attack and minor ischaemic stroke

Using a prospective hospital-based registry, 146 patients with transient ischaemic attack (TIA) were compared with 376 patients with minor first-ever ischaemic stroke with respect to the 3-month risk of subsequent vascular events, in order to clarify the distinctions between the disease entities. All patients were enrolled within 48 h of onset. The risk factor distribution for the two groups was comparable, except that the TIA patients had more previous TIAs. Large artery atherosclerosis (34%) and small vessel occlusion (32%) were the main aetiologies in the TIA group, whereas small vessel occlusion (49%) was the major cause in the stroke group. The 3-month risk of combined endpoints of stroke, myocardial infarction, and vascular death for TIA patients was higher than that for the minor stroke group (15.1% vs. 3.2%; hazard ratio 4.6, 95% confidence interval 2.3-9.3 in multivariate analysis). Large artery atherosclerosis and male sex were the other significant predictors. TIA may demand more urgent management than minor stroke. The fact that aetiology is a predictor, highlights the need for rapid diagnostic tests to establish pathogenesis.

Risk Factors for Early Recurrent Cerebral Ischemia Before Treatment of Symptomatic Carotid Stenosis

Background and Purpose— In patients with a recently symptomatic carotid stenosis, surgical or interventional treatment is often delayed for weeks to months. Because therapy should be instituted as early as possible in patients at highest risk for recurrent ischemia, the aim of this study was to identify these individuals using clinical data and serial diffusion-weighted imaging (DWI).

Methods— One hundred thirty-one patients (98 male; mean age 68±9 years) who had been referred to our department within 14 days (median; interquartile range, 4 to 36 days) after experiencing an ischemic event caused by a carotid stenosis were followed-up until carotid angioplasty and stenting. Risk factors predicting recurrent transient ischemic attack, stroke, or new DWI lesions were examined.

Results— During a median follow-up period of 7 days (interquartile range, 5 to 13 days) no patient experienced a stroke, 4 patients (3.1%) developed a hemispherical transient ischemic attack, and in 15 patients (12%) new asymptomatic DWI lesions were present in the territory of the treated artery. Multivariable regression analysis revealed that motor symptoms (odds ratio, 5.6; 95% CI, 1.2 to 26.3; P <0.05) or the presence of a contralateral carotid occlusion (odds ratio, 4.6; 95% CI, 1.0 to 20.4; P <0.05) were significant independent predictors of further cerebral ischemic events before carotid angioplasty and stenting.

Conclusions— In patients with a recently symptomatic carotid stenosis, the risk of early recurrent ischemia is highest in those with motor symptoms and in those with a contralateral carotid occlusion. In these high-risk patients urgent preventive treatment might be warranted.

Validation of the ABCD Score in Identifying Individuals at High Early Risk of Stroke After a Transient Ischemic Attack

BACKGROUND AND PURPOSE

A simple score derived in the Oxfordshire Community Stroke Project (ABCD score) was able to identify individuals at high early risk of stroke after a transient ischemic attack (TIA) both in a population-based and a hospital-referred clinic cohort. We aimed to further validate the former score in a cohort of hospitalized TIA patients.

METHODS

We retrospectively reviewed the emergency room and hospital records of consecutive patients hospitalized in our neurological department with a definite TIA according to the World Health Organization (WHO) criteria during a 5-year period. The 6-point ABCD score (age [<60 years=0, > or =60 years=1]; blood pressure [systolic < or =140 mm Hg and diastolic < or =90 mm Hg=0, systolic >140 mm Hg and/or diastolic >90 mm Hg=1]; clinical features [unilateral weakness=2, speech disturbance without weakness=1, other symptom=0]; duration of symptoms [<10 minutes=0, 10 to 59 minutes=1, > or =60 minutes=2]) was used to stratify the 30-day stroke risk.

RESULTS

The 30-day risk of stroke in the present case series (n=226) was 9.7% (95% CI, 5.8% to 13.6%). The ABCD score was highly predictive of 30-day risk of stroke (ABCD=0 to 2: 0%, ABCD=3: 3.5% [95% CI, 0% to 8.2%], ABCD=4: 7.6% [95% CI, 1.2% to 14.0%], ABCD=5: 21.3% [95% CI, 10.4% to 33.0%], ABCD=6: 31.3% [95% CI, 8.6% to 54.0%]; log-rank test=23.09; df=6; P=0.0008; P for linear trend across the ABCD score levels <0.00001). After adjustment for stroke risk factors, history of previous TIA, medication use before the index TIA, and secondary prevention treatment strategies, an ABCD score of 5 to 6 was independently (P<0.001) associated with an 8-fold greater 30-day risk of stroke (hazard ratio, 8.01; 95% CI, 3.21 to 19.98).

CONCLUSIONS

Our findings validate the predictive value of the ABCD score in identifying hospitalized TIA patients with a high risk of early stroke and provide further evidence for its potential applicability in clinical practice.

National Stroke Association guidelines for the management of transient ischemic attacks

OBJECTIVE

Transient ischemic attacks are common and important harbingers of subsequent stroke. Management varies widely, and most published guidelines have not been updated in several years. We sought to create comprehensive, unbiased, evidence-based guidelines for the management of patients with transient ischemic attacks.

METHODS

Fifteen expert panelists were selected based on objective criteria, using publication metrics that predicted nomination by practitioners in the field. Prior published guidelines were identified through systematic review, and recommendations derived from them were rated independently for quality by the experts. Highest quality recommendations were selected and subsequently edited by the panelists using a modified Delphi approach with multiple iterations of questionnaires to reach consensus on new changes. Experts were provided systematic reviews of recent clinical studies and were asked to justify wording changes based on new evidence and to rate the final recommendations based on level of evidence and quality. No expert was allowed to contribute to recommendations on a topic for which there could be any perception of a conflict of interest.

RESULTS

Of 257 guidelines documents identified by systematic review, 13 documents containing 137 recommendations met all entry criteria. Six iterations of questionnaires were required to reach consensus on wording of 53 final recommendations. Final recommendations covered initial management, evaluation, medical treatment, surgical treatment, and risk factor management.

INTERPRETATION

The final recommendations on the care of patients with transient ischemic attacks emphasize the importance of urgent evaluation and treatment. The novel approach used to develop these guidelines is feasible, allows for rapid updating, and may reduce bias.

Primary Stroke Unit Treatment Followed by Very Early Carotid Endarterectomy for Carotid Artery Stenosis after Acute Stroke

BACKGROUND

Although it is recognized that carotid endarterectomy (CEA) is the treatment of choice in symptomatic internal carotid artery (ICA) stenosis, in the past, very early CEA has been shown to carry substantial risks. We assessed an interdisciplinary concept of very early CEA in patients with high-grade (>70%) symptomatic ICA stenosis at a single center.

PATIENTS AND METHODS

The course of treatment and outcomes of patients who underwent CEA as early as possible after being referred to the stroke unit for symptoms of transient ischemic attack and stroke were prospectively evaluated, including the following parameters: age, severity of ischemia-related symptoms according to the modified Rankin scale, duration of symptoms until admission, multimodal imaging findings (color-coded duplex, cranial computed tomography, magnetic resonance imaging, positron emission tomography), duration until CEA, perioperative course and complications, as well as duration of in-hospital care.

RESULTS

Fifty consecutive patients (median age 68 years, range 44-90) with clinical and imaging signs of transient ischemic attack (n = 19) or stroke (n = 31) were included from January 2000 until December 2004. All except 1 patient showed a preoperative Rankin < 4. There was a median time period of 6 h between the onset of symptoms and admission (range 1 h to 15 days) and a median duration of 4 days after admission until operation (range 1-21 days). Seven patients underwent CEA of the contralateral, severely stenosed ICA after symptomatic ipsilateral ICA occlusion. Four out of 5 patients who primarily underwent systemic thrombolysis recovered almost completely. Three patients (6%) experienced a clinical deterioration before surgery. In the majority of patients (43/50), CEA was performed under local anesthesia with selective shunt use which became necessary in 26%. Three patients (6%) had postoperative worsening due to new infarcts. In 2 cases, an intracerebral hemorrhage occurred, of which 1 remained asymptomatic. In 1 case, surgical revision was necessary because of an ICA thrombosis without permanent neurological decline. Patients were discharged after a median time of 14.5 days (range 4-44).

CONCLUSIONS

After careful selection and preparation in a stroke unit, patients with acute stroke due to carotid stenosis can undergo very early CEA under local anesthesia with a perioperative risk comparable with the risk of later endarterectomy, therefore preventing very early stroke recurrences.

National study on emergency department visits for transient ischemic attack, 1992-2001

OBJECTIVES

To describe the epidemiology of U.S. emergency department (ED) visits for transient ischemic attack (TIA) and to measure rates of antiplatelet medication use, neuroimaging, and hospitalization during a ten-year time period.

METHODS

The authors obtained data from the 1992-2001 National Hospital Ambulatory Medical Care Survey. TIA cases were identified by having ICD-9 code 435.

RESULTS

From 1992 to 2001, there were 769 cases, representing 2,969,000 ED visits for TIA. The population rate of 1.1 ED visits per 1,000 U.S. population (95% CI = 0.92 to 1.30) was stable over time. TIA was diagnosed in 0.3% of all ED visits. Physicians administered aspirin and other antiplatelet agents to a small percentage of patients, and 42% of TIA patients (95% CI = 29% to 55%) received no medications at all in the ED. Too few data points existed to measure a statistically valid trend over time. Physicians performed computed tomography scanning in 56% (95% CI = 45% to 66%) of cases and performed magnetic resonance imaging (MRI) in < 5% of cases, and there was a trend toward increased imaging over time. Admission rates did not increase during the ten-year period, with 54% (95% CI = 42% to 67%) admitted. Regional differences were noted, however, with the highest admission rate found in the Northeast (68%).

CONCLUSIONS

Between 1992 and 2001, the population rate of ED visits for TIA was stable, as were admission rates (54%). Antiplatelet medications appear to be underutilized and to be discordant with published guidelines. Neuroimaging increased significantly. These findings may reflect the limited evidence base for the guidelines, educational deficits, or other barriers to guideline implementation.

Stroke Imaging at 3.0 T

Stroke is a devastating disease with a complex pathophysiology. It is a major cause of death and disability in North America. To fully characterize its extent and effects, one requires numerous specialized anatomical and functional MR techniques, specifically diffusion-weighted imaging, MR angiography, and perfusion-weighted imaging. The advent of 3.0 T clinical scanners has the potential to provide higher quality information in potentially less time compared with 1.5 T stroke-specific MR imaging protocols. This article gives a brief overview of stroke, presents the principles and clinical applications of the relevant MR techniques required for diagnostic stroke imaging at high field, and discusses the advantages, challenges, and limitations of 3.0 T imaging as they relate to stroke.

The use of neurovascular imaging for triaging tia and minor stroke: Implications for therapy

Nondisabling cerebrovascular events (minor stroke or transient ischemic attack) are not benign; a significant proportion of these patients will suffer a new disabling stroke or develop stroke progression in hospital, resulting in dependence or death. With the exception of the modest benefits of aspirin, there are currently no effective acute medical therapies to prevent early progression or recurrence in such patients. Early carotid revascularization appears to be the most efficacious treatment available for patients with symptomatic (> 50%) internal carotid artery stenosis. More acute treatment and acute prevention trials are needed. MRI, CT bolus techniques, and transcranial Doppler emboli detection represent tools for detection of patients at high risk for deterioration and should be incorporated into the development of effective therapies by targeting the most appropriate patients for intervention.

Efectividad del estudio ultrasonográfico precoz en el pronóstico a corto plazo de los pacientes con un accidente vascular cerebral isquémico transitorio

BACKGROUND AND OBJECTIVE

Although patients with ischemic attacks (TIA) experience cardiovascular events frequently within the first 90 days after symptoms onset, strong clinical predictors of early recurrence are lacking. We investigate the value of combined carotid/transcranial ultrasound testing (UST) on the prognosis of TIA patients.

PATIENTS AND METHOD

UST was performed < 24 h after symptoms onset among 311 consecutive TIA patients. Stroke recurrence, myocardial infarction, or any vascular event was recorded at 7 and 90 days of follow-up.

RESULTS

A total of 20 patients suffered an stroke within 7 days of symptoms onset. During the next 90 days after index TIA, 58 (18.6%) patients experienced an endpoint: 51 cerebral ischemic events, one peripheral arterial disease, 5 myocardial infarctions and one cerebellum hemorrhage. Cox proportional hazards multivariate analyses identified the presence of intracranial stenoses (HR = 3.05; 95% CI, 1.21-7.70; p = 0.018) and carotid territory implication (HR = 15.91; 95% CI, 2.11-120.04; p = 0.007) as independent predictors of stroke within the first 7 days after index TIA. Moreover, at 90 days of follow-up, large-artery occlusive disease was an independent predictor of stroke (HR = 3.07; 95% CI, 1.76-5.38; p < 0.001).

CONCLUSIONS

TIA patients with moderate to severe intracranial or extracranial stenoses have a higher risk of stroke recurrence. The routine use of UST within the first 24 h after index TIA can be useful for identifying those patients at high risk in order to plan aggressive prevention therapies.