A randomised, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE). CAPRIE Steering Committee

BACKGROUND

Many clinical trials have evaluated the benefit of long-term use of antiplatelet drugs in reducing the risk of clinical thrombotic events. Aspirin and ticlopidine have been shown to be effective, but both have potentially serious adverse effects. Clopidogrel, a new thienopyridine derivative similar to ticlopidine, is an inhibitor of platelet aggregation induced by adenosine diphosphate.

METHODS

CAPRIE was a randomised, blinded, international trial designed to assess the relative efficacy of clopidogrel (75 mg once daily) and aspirin (325 mg once daily) in reducing the risk of a composite outcome cluster of ischaemic stroke, myocardial infarction, or vascular death; their relative safety was also assessed. The population studied comprised subgroups of patients with atherosclerotic vascular disease manifested as either recent ischaemic stroke, recent myocardial infarction, or symptomatic peripheral arterial disease. Patients were followed for 1 to 3 years.

FINDINGS

19,185 patients, with more than 6300 in each of the clinical subgroups, were recruited over 3 years, with a mean follow-up of 1.91 years. There were 1960 first events included in the outcome cluster on which an intention-to-treat analysis showed that patients treated with clopidogrel had an annual 5.32% risk of ischaemic stroke, myocardial infarction, or vascular death compared with 5.83% with aspirin. These rates reflect a statistically significant (p = 0.043) relative-risk reduction of 8.7% in favour of clopidogrel (95% Cl 0.3-16.5). Corresponding on-treatment analysis yielded a relative-risk reduction of 9.4%. There were no major differences in terms of safety. Reported adverse experiences in the clopidogrel and aspirin groups judged to be severe included rash (0.26% vs 0.10%), diarrhoea (0.23% vs 0.11%), upper gastrointestinal discomfort (0.97% vs 1.22%), intracranial haemorrhage (0.33% vs 0.47%), and gastrointestinal haemorrhage (0.52% vs 0.72%), respectively. There were ten (0.10%) patients in the clopidogrel group with significant reductions in neutrophils (< 1.2 x 10(9)/L) and 16 (0.17%) in the aspirin group.

INTERPRETATION

Long-term administration of clopidogrel to patients with atherosclerotic vascular disease is more effective than aspirin in reducing the combined risk of ischaemic stroke, myocardial infarction, or vascular death. The overall safety profile of clopidogrel is at least as good as that of medium-dose aspirin.

Inflammation, aspirin, and the risk of cardiovascular disease in apparently healthy men

BACKGROUND

Inflammation may be important in the pathogenesis of atherothrombosis. We studied whether inflammation increases the risk of a first thrombotic event and whether treatment with aspirin decreases the risk.

METHODS

We measured plasma C-reactive protein, a marker for systemic inflammation, in 543 apparently healthy men participating in the Physicians' Health Study in whom myocardial infarction, stroke, or venous thrombosis subsequently developed, and in 543 study participants who did not report vascular disease during a follow-up period exceeding eight years. Subjects were randomly assigned to receive aspirin or placebo at the beginning of the trial.

RESULTS

Base-line plasma C-reactive protein concentrations were higher among men who went on to have myocardial infarction (1.51 vs. 1.13 mg per liter, P<0.001) or ischemic stroke (1.38 vs. 1.13 mg per liter, P=0.02), but not venous thrombosis (1.26 vs. 1.13 mg per liter, P=0.34), than among men without vascular events. The men in the quartile with the highest levels of C-reactive protein values had three times the risk of myocardial infarction (relative risk, 2.9; P<0.001) and two times the risk of ischemic stroke (relative risk, 1.9; P=0.02) of the men in the lowest quartile. Risks were stable over long periods, were not modified by smoking, and were independent of other lipid-related and non-lipid-related risk factors. The use of aspirin was associated with significant reductions in the risk of myocardial infarction (55.7 percent reduction, P=0.02) among men in the highest quartile but with only small, nonsignificant reductions among those in the lowest quartile (13.9 percent, P=0.77).

CONCLUSIONS

The base-line plasma concentration of C-reactive protein predicts the risk of future myocardial infarction and stroke. Moreover, the reduction associated with the use of aspirin in the risk of a first myocardial infarction appears to be directly related to the level of C-reactive protein, raising the possibility that antiinflammatory agents may have clinical benefits in preventing cardiovascular disease.

Blockade of N-methyl-D-aspartate receptors may protect against ischemic damage in the brain

In rats ischemia of the forebrain induced by a 30-minute occlusion of the carotid artery, followed by 120 minutes of arterial reperfusion, produced ischemic lesions of selectively vulnerable pyramidal cells in both hippocampi. Focal microinfusion into the dorsal hippocampus of 2-amino-7-phosphonoheptanoic acid, an antagonist of excitation at the N-methyl-D-aspartate-preferring receptor, before ischemia was induced protected against the development of ischemic damage. It is proposed that excitatory neurotransmission plays an important role in selective neuronal loss due to cerebral ischemia.

Subarachnoid haemorrhage

Subarachnoid haemorrhage accounts for only 5% of strokes, but occurs at a fairly young age. Sudden headache is the cardinal feature, but patients might not report the mode of onset. CT brain scanning is normal in most patients with sudden headache, but to exclude subarachnoid haemorrhage or other serious disorders, a carefully planned lumbar puncture is also needed. Aneurysms are the cause of subarachnoid haemorrhage in 85% of cases. The case fatality after aneurysmal haemorrhage is 50%; one in eight patients with subarachnoid haemorrhage dies outside hospital. Rebleeding is the most imminent danger; a first aim is therefore occlusion of the aneurysm. Endovascular obliteration by means of platinum spirals (coiling) is the preferred mode of treatment, but some patients require a direct neurosurgical approach (clipping). Another complication is delayed cerebral ischaemia; the risk is reduced with oral nimodipine and probably by maintaining circulatory volume. Hydrocephalus might cause gradual obtundation in the first few hours or days; it can be treated by lumbar puncture or ventricular drainage, dependent on the site of obstruction.

Failure of extracranial-intracranial arterial bypass to reduce the risk of ischemic stroke. Results of an international randomized trial

To determine whether bypass surgery would benefit patients with symptomatic atherosclerotic disease of the internal carotid artery, we studied 1377 patients with recent hemisphere strokes, retinal infarction, or transient ischemic attacks who had atherosclerotic narrowing or occlusion of the ipsilateral internal carotid or middle cerebral artery. Of these, 714 were randomly assigned to the best medical care, and 663 to the same regimen with the addition of bypass surgery joining the superficial temporal artery and the middle cerebral artery. The patients were followed for an average of 55.8 months. Thirty-day surgical mortality and major stroke morbidity rates were 0.6 and 2.5 per cent, respectively. The postoperative bypass patency rate was 96 per cent. Nonfatal and fatal stroke occurred both more frequently and earlier in the patients operated on. Secondary survival analyses comparing the two groups for major strokes and all deaths, for all strokes and all deaths, and for ipsilateral ischemic strokes demonstrated a similar lack of benefit from surgery. Separate analyses in patients with different angiographic lesions did not identify a subgroup with any benefit from surgery. Two important subgroups of patients fared substantially worse in the surgical group: those with severe middle-cerebral-artery stenosis (n = 109, Mantel-Haenszel chi-square = 4.74), and those with persistence of ischemic symptoms after an internal-carotid-artery occlusion had been demonstrated (n = 287, chi-square = 4.04). This study thus failed to confirm the hypothesis that extracranial-intracranial anastomosis is effective in preventing cerebral ischemia in patients with atherosclerotic arterial disease in the carotid and middle cerebral arteries.

Clopidogrel and Aspirin in Acute Ischemic Stroke and High-Risk TIA

BACKGROUND

Combination antiplatelet therapy with clopidogrel and aspirin may reduce the rate of recurrent stroke during the first 3 months after a minor ischemic stroke or transient ischemic attack (TIA). A trial of combination antiplatelet therapy in a Chinese population has shown a reduction in the risk of recurrent stroke. We tested this combination in an international population.

METHODS

In a randomized trial, we assigned patients with minor ischemic stroke or high-risk TIA to receive either clopidogrel at a loading dose of 600 mg on day 1, followed by 75 mg per day, plus aspirin (at a dose of 50 to 325 mg per day) or the same range of doses of aspirin alone. The dose of aspirin in each group was selected by the site investigator. The primary efficacy outcome in a time-to-event analysis was the risk of a composite of major ischemic events, which was defined as ischemic stroke, myocardial infarction, or death from an ischemic vascular event, at 90 days.

RESULTS

A total of 4881 patients were enrolled at 269 international sites. The trial was halted after 84% of the anticipated number of patients had been enrolled because the data and safety monitoring board had determined that the combination of clopidogrel and aspirin was associated with both a lower risk of major ischemic events and a higher risk of major hemorrhage than aspirin alone at 90 days. Major ischemic events occurred in 121 of 2432 patients (5.0%) receiving clopidogrel plus aspirin and in 160 of 2449 patients (6.5%) receiving aspirin plus placebo (hazard ratio, 0.75; 95% confidence interval [CI], 0.59 to 0.95; P=0.02), with most events occurring during the first week after the initial event. Major hemorrhage occurred in 23 patients (0.9%) receiving clopidogrel plus aspirin and in 10 patients (0.4%) receiving aspirin plus placebo (hazard ratio, 2.32; 95% CI, 1.10 to 4.87; P=0.02).

CONCLUSIONS

In patients with minor ischemic stroke or high-risk TIA, those who received a combination of clopidogrel and aspirin had a lower risk of major ischemic events but a higher risk of major hemorrhage at 90 days than those who received aspirin alone. (Funded by the National Institute of Neurological Disorders and Stroke; POINT ClinicalTrials.gov number, NCT00991029 .).

A tetracycline derivative, minocycline, reduces inflammation and protects against focal cerebral ischemia with a wide therapeutic window

The only treatment of patients with acute ischemic stroke is thrombolytic therapy, which benefits only a fraction of stroke patients. Both human and experimental studies indicate that ischemic stroke involves secondary inflammation that significantly contributes to the outcome after ischemic insult. Minocycline is a semisynthetic second-generation tetracycline that exerts antiinflammatory effects that are completely separate from its antimicrobial action. Because tetracycline treatment is clinically well tolerated, we investigated whether minocycline protects against focal brain ischemia with a wide therapeutic window. Using a rat model of transient middle cerebral artery occlusion, we show that daily treatment with minocycline reduces cortical infarction volume by 76 +/- 22% when the treatment is started 12 h before ischemia and by 63 +/- 35% when started even 4 h after the onset of ischemia. The treatment inhibits morphological activation of microglia in the area adjacent to the infarction, inhibits induction of IL-1beta-converting enzyme, and reduces cyclooxygenase-2 expression and prostaglandin E(2) production. Minocycline had no effect on astrogliosis or spreading depression, a wave of ionic transients thought to contribute to enlargement of cortical infarction. Treatment with minocycline may act directly on brain cells, because cultured primary neurons were also salvaged from glutamate toxicity. Minocycline may represent a prototype of an antiinflammatory compound that provides protection against ischemic stroke and has a clinically relevant therapeutic window.

Subarachnoid haemorrhage: diagnosis, causes and management

The incidence of subarachnoid haemorrhage (SAH) is stable, at around six cases per 100 000 patient years. Any apparent decrease is attributable to a higher rate of CT scanning, by which other haemorrhagic conditions are excluded. Most patients are <60 years of age. Risk factors are the same as for stroke in general; genetic factors operate in only a minority. Case fatality is approximately 50% overall (including pre-hospital deaths) and one-third of survivors remain dependent. Sudden, explosive headache is a cardinal but non-specific feature in the diagnosis of SAH: in general practice, the cause is innocuous in nine out of 10 patients in whom this is the only symptom. CT scanning is mandatory in all, to be followed by (delayed) lumbar puncture if CT is negative. The cause of SAH is a ruptured aneurysm in 85% of cases, non-aneurysmal perimesencephalic haemorrhage (with excellent prognosis) in 10%, and a variety of rare conditions in 5%. Catheter angiography for detecting aneurysms is gradually being replaced by CT angiography. A poor clinical condition on admission may be caused by a remediable complication of the initial bleed or a recurrent haemorrhage in the form of intracranial haematoma, acute hydrocephalus or global brain ischaemia. Occlusion of the aneurysm effectively prevents rebleeding, but there is a dearth of controlled trials assessing the relative benefits of early operation (within 3 days) versus late operation (day 10-12), or that of endovascular treatment versus any operation. Antifibrinolytic drugs reduce the risk of rebleeding, but do not improve overall outcome. Measures of proven value in decreasing the risk of delayed cerebral ischaemia are a liberal supply of fluids, avoidance of antihypertensive drugs and administration of nimodipine. Once ischaemia has occurred, treatment regimens such as a combination of induced hypertension and hypervolaemia, or transluminal angioplasty, are plausible, but of unproven benefit.

A comparison of warfarin and aspirin for the prevention of recurrent ischemic stroke

BACKGROUND

Despite the use of antiplatelet agents, usually aspirin, in patients who have had an ischemic stroke, there is still a substantial rate of recurrence. Therefore, we investigated whether warfarin, which is effective and superior to aspirin in the prevention of cardiogenic embolism, would also prove superior in the prevention of recurrent ischemic stroke in patients with a prior noncardioembolic ischemic stroke.

METHODS

In a multicenter, double-blind, randomized trial, we compared the effect of warfarin (at a dose adjusted to produce an international normalized ratio of 1.4 to 2.8) and that of aspirin (325 mg per day) on the combined primary end point of recurrent ischemic stroke or death from any cause within two years.

RESULTS

The two randomized study groups were similar with respect to base-line risk factors. In the intention-to-treat analysis, no significant differences were found between the treatment groups in any of the outcomes measured. The primary end point of death or recurrent ischemic stroke was reached by 196 of 1103 patients assigned to warfarin (17.8 percent) and 176 of 1103 assigned to aspirin (16.0 percent; P=0.25; hazard ratio comparing warfarin with aspirin, 1.13; 95 percent confidence interval, 0.92 to 1.38). The rates of major hemorrhage were low (2.22 per 100 patient-years in the warfarin group and 1.49 per 100 patient-years in the aspirin group). Also, there were no significant treatment-related differences in the frequency of or time to the primary end point or major hemorrhage according to the cause of the initial stroke (1237 patients had had previous small-vessel or lacunar infarcts, 576 had had cryptogenic infarcts, and 259 had had infarcts designated as due to severe stenosis or occlusion of a large artery).

CONCLUSIONS

Over two years, we found no difference between aspirin and warfarin in the prevention of recurrent ischemic stroke or death or in the rate of major hemorrhage. Consequently, we regard both warfarin and aspirin as reasonable therapeutic alternatives.

Effects of cholesterol-lowering with simvastatin on stroke and other major vascular events in 20536 people with cerebrovascular disease or other high-risk conditions

BACKGROUND

Lower blood cholesterol concentrations have consistently been found to be strongly associated with lower risks of coronary disease but not with lower risks of stroke. Despite this observation, previous randomised trials had indicated that cholesterol-lowering statin therapy reduces the risk of stroke, but large-scale prospective confirmation has been needed.

METHODS

3280 adults with cerebrovascular disease, and an additional 17256 with other occlusive arterial disease or diabetes, were randomly allocated 40 mg simvastatin daily or matching placebo. Subgroup analyses were prespecified of first "major vascular event" (ie, non-fatal myocardial infarction or coronary death, stroke of any type, or any revascularisation procedure) in prior disease subcategories. Subsidiary outcomes included any stroke, and stroke sub-type. Comparisons are of all simvastatin-allocated versus all placebo-allocated participants (ie, "intention-to-treat"), which yielded an average difference in LDL cholesterol of 1.0 mmol/L (39 mg/dL) during the 5-year treatment period.

FINDINGS

Overall, there was a highly significant 25% (95% CI 15-34) proportional reduction in the first event rate for stroke (444 [4.3%] simvastatin vs 585 [5.7%] placebo; p<0.0001), reflecting a definite 28% (19-37) reduction in presumed ischaemic strokes (p<0.0001) and no apparent difference in strokes attributed to haemorrhage (51 [0.5%] vs 53 [0.5%]; rate ratio 0.95 [0.65-1.40]; p=0.8). In addition, simvastatin reduced the numbers having transient cerebral ischaemic attacks alone (2.0% vs 2.4%; p=0.02) or requiring carotid endarterectomy or angioplasty (0.4% vs 0.8%; p=0.0003). The reduction in stroke was not significant during the first year, but was already significant (p=0.0004) by the end of the second year. Among patients with pre-existing cerebrovascular disease there was no apparent reduction in the stroke rate, but there was a highly significant 20% (8-29) reduction in the rate of any major vascular event (406 [24.7%] vs 488 [29.8%]; p=0.001). The proportional reductions in stroke were about one-quarter in each of the other subcategories of participant studied, including: those with coronary disease or diabetes; those aged under or over 70 years at entry; and those presenting with different levels of blood pressure or lipids (even when the pretreatment LDL cholesterol was below 3.0 mmol/L [116 mg/dL]).

INTERPRETATION

Much larger numbers of people in the present study suffered a stroke than in any previous cholesterol-lowering trial. The results demonstrate that statin therapy rapidly reduces the incidence not only of coronary events but also of ischaemic strokes, with no apparent effect on cerebral haemorrhage, even among individuals who do not have high cholesterol concentrations. Allocation to 40 mg simvastatin daily reduced the rate of ischaemic strokes by about one-quarter and so, after making allowance for non-compliance in the trial, actual use of this regimen would probably reduce the stroke rate by about a third. HPS also provides definitive evidence that statin therapy is beneficial for people with pre-existing cerebrovascular disease, even if they do not already have manifest coronary disease.

Hypoxia-inducible factor 1: oxygen homeostasis and disease pathophysiology

Hypoxia-inducible factor 1 (HIF-1) activates transcription of genes encoding proteins that mediate adaptive responses to reduced oxygen availability. The HIF-1beta subunit is constitutively expressed, whereas the HIF-1alpha subunit is subject to ubiquitination and proteasomal degradation, a process that is inhibited under hypoxic conditions. Recent data indicate that HIF-1 plays major roles in the prevention of myocardial and cerebral ischemia and in the pathogenesis of pulmonary hypertension and cancer. Modulation of HIF-1 activity by genetic or pharmacological means could provide a novel therapeutic approach to these common causes of mortality.

Rivaroxaban for Stroke Prevention after Embolic Stroke of Undetermined Source

BACKGROUND

Embolic strokes of undetermined source represent 20% of ischemic strokes and are associated with a high rate of recurrence. Anticoagulant treatment with rivaroxaban, an oral factor Xa inhibitor, may result in a lower risk of recurrent stroke than aspirin.

METHODS

We compared the efficacy and safety of rivaroxaban (at a daily dose of 15 mg) with aspirin (at a daily dose of 100 mg) for the prevention of recurrent stroke in patients with recent ischemic stroke that was presumed to be from cerebral embolism but without arterial stenosis, lacune, or an identified cardioembolic source. The primary efficacy outcome was the first recurrence of ischemic or hemorrhagic stroke or systemic embolism in a time-to-event analysis; the primary safety outcome was the rate of major bleeding.

RESULTS

A total of 7213 participants were enrolled at 459 sites; 3609 patients were randomly assigned to receive rivaroxaban and 3604 to receive aspirin. Patients had been followed for a median of 11 months when the trial was terminated early because of a lack of benefit with regard to stroke risk and because of bleeding associated with rivaroxaban. The primary efficacy outcome occurred in 172 patients in the rivaroxaban group (annualized rate, 5.1%) and in 160 in the aspirin group (annualized rate, 4.8%) (hazard ratio, 1.07; 95% confidence interval [CI], 0.87 to 1.33; P=0.52). Recurrent ischemic stroke occurred in 158 patients in the rivaroxaban group (annualized rate, 4.7%) and in 156 in the aspirin group (annualized rate, 4.7%). Major bleeding occurred in 62 patients in the rivaroxaban group (annualized rate, 1.8%) and in 23 in the aspirin group (annualized rate, 0.7%) (hazard ratio, 2.72; 95% CI, 1.68 to 4.39; P<0.001).

CONCLUSIONS

Rivaroxaban was not superior to aspirin with regard to the prevention of recurrent stroke after an initial embolic stroke of undetermined source and was associated with a higher risk of bleeding. (Funded by Bayer and Janssen Research and Development; NAVIGATE ESUS ClinicalTrials.gov number, NCT02313909 .).

Aspirin and extended-release dipyridamole versus clopidogrel for recurrent stroke

BACKGROUND

Recurrent stroke is a frequent, disabling event after ischemic stroke. This study compared the efficacy and safety of two antiplatelet regimens--aspirin plus extended-release dipyridamole (ASA-ERDP) versus clopidogrel.

METHODS

In this double-blind, 2-by-2 factorial trial, we randomly assigned patients to receive 25 mg of aspirin plus 200 mg of extended-release dipyridamole twice daily or to receive 75 mg of clopidogrel daily. The primary outcome was first recurrence of stroke. The secondary outcome was a composite of stroke, myocardial infarction, or death from vascular causes. Sequential statistical testing of noninferiority (margin of 1.075), followed by superiority testing, was planned.

RESULTS

A total of 20,332 patients were followed for a mean of 2.5 years. Recurrent stroke occurred in 916 patients (9.0%) receiving ASA-ERDP and in 898 patients (8.8%) receiving clopidogrel (hazard ratio, 1.01; 95% confidence interval [CI], 0.92 to 1.11). The secondary outcome occurred in 1333 patients (13.1%) in each group (hazard ratio for ASA-ERDP, 0.99; 95% CI, 0.92 to 1.07). There were more major hemorrhagic events among ASA-ERDP recipients (419 [4.1%]) than among clopidogrel recipients (365 [3.6%]) (hazard ratio, 1.15; 95% CI, 1.00 to 1.32), including intracranial hemorrhage (hazard ratio, 1.42; 95% CI, 1.11 to 1.83). The net risk of recurrent stroke or major hemorrhagic event was similar in the two groups (1194 ASA-ERDP recipients [11.7%], vs. 1156 clopidogrel recipients [11.4%]; hazard ratio, 1.03; 95% CI, 0.95 to 1.11).

CONCLUSIONS

The trial did not meet the predefined criteria for noninferiority but showed similar rates of recurrent stroke with ASA-ERDP and with clopidogrel. There is no evidence that either of the two treatments was superior to the other in the prevention of recurrent stroke. (ClinicalTrials.gov number, NCT00153062.)

Fruit and vegetable intake in relation to risk of ischemic stroke

CONTEXT

Few studies have evaluated the relationship between fruit and vegetable intake and cardiovascular disease.

OBJECTIVE

To examine the associations between fruit and vegetable intake and ischemic stroke.

DESIGN, SETTING, AND SUBJECTS

Prospective cohort studies, including 75 596 women aged 34 to 59 years in the Nurses' Health Study with 14 years of follow-up (1980-1994), and 38683 men aged 40 to 75 years in the Health Professionals' Follow-up Study with 8 years of follow-up (1986-1994). All individuals were free of cardiovascular disease, cancer, and diabetes at baseline.

MAIN OUTCOME MEASURE

Incidence of ischemic stroke by quintile of fruit and vegetable intake.

RESULTS

A total of 366 women and 204 men had an ischemic stroke. After controlling for standard cardiovascular risk factors, persons in the highest quintile of fruit and vegetable intake (median of 5.1 servings per day among men and 5.8 servings per day among women) had a relative risk (RR) of 0.69 (95% confidence interval [CI], 0.52-0.92) compared with those in the lowest quintile. An increment of 1 serving per day of fruits or vegetables was associated with a 6% lower risk of ischemic stroke (RR, 0.94; 95 % CI, 0.90-0.99; P =.01, test for trend). Cruciferous vegetables (RR, 0.68 for an increment of 1 serving per day; 95% CI, 0.49-0.94), green leafy vegetables (RR, 0.79; 95% CI, 0.62-0.99), citrus fruit including juice (RR, 0.81; 95% CI, 0.68-0.96), and citrus fruit juice (RR, 0.75; 95% CI, 0.61-0.93) contributed most to the apparent protective effect of total fruits and vegetables. Legumes or potatoes were not associated with lower ischemic stroke risk. The multivariate pooled RR for total stroke was 0.96 (95% CI, 0.93-1.00) for each increment of 2 servings per day.

CONCLUSIONS

These data support a protective relationship between consumption of fruit and vegetables-particularly cruciferous and green leafy vegetables and citrus fruit and juice-and ischemic stroke risk.

Management of stroke in infants and children: a scientific statement from a Special Writing Group of the American Heart Association Stroke Council and the Council on Cardiovascular Disease in the Young

PURPOSE

The purpose of this statement is to review the literature on childhood stroke and to provide recommendations for optimal diagnosis and treatment. This statement is intended for physicians who are responsible for diagnosing and treating infants, children, and adolescents with cerebrovascular disease.

METHODS

The Writing Group members were appointed by the American Heart Association Stroke Council's Scientific Statement Oversight Committee. The panel included members with several different areas of expertise. Each of the panel's recommendations was weighted by applying the American Heart Association Stroke Council's Levels of Evidence grading algorithm. After being reviewed by panel members, the manuscript was reviewed by 4 expert peer reviewers and by members of the Stroke Council Leadership Committee and was approved by the American Heart Association Science Advisory and Coordinating Committee. We anticipate that this statement will need to be updated in 4 years.

RESULTS

Evidence-based recommendations are provided for the prevention of ischemic stroke caused by sickle cell disease, moyamoya disease, cervicocephalic arterial dissection, and cardiogenic embolism. Recommendations on the evaluation and management of hemorrhagic stroke also are provided. Protocols for dosing of heparin and warfarin in children are suggested. Also included are recommendations on the evaluation and management of perinatal stroke and cerebral sinovenous thrombosis in children.

NMDA receptor subunits have differential roles in mediating excitotoxic neuronal death both in vitro and in vivo

Well-documented experimental evidence from both in vitro and in vivo models of stroke strongly supports the critical involvement of NMDA receptor-mediated excitotoxicity in neuronal damage after stroke. Despite this, the results of clinical trials testing NMDA receptor antagonists as neuroprotectants after stroke and brain trauma have been discouraging. Here, we report that in mature cortical cultures, activation of either synaptic or extrasynaptic NR2B-containing NMDA receptors results in excitotoxicity, increasing neuronal apoptosis. In contrast, activation of either synaptic or extrasynaptic NR2A-containing NMDA receptors promotes neuronal survival and exerts a neuroprotective action against both NMDA receptor-mediated and non-NMDA receptor-mediated neuronal damage. A similar opposing action of NR2B and NR2A in mediating cell death and cell survival was also observed in an in vivo rat model of focal ischemic stroke. Moreover, we found that blocking NR2B-mediated cell death was effective in reducing infarct volume only when the receptor antagonist was given before the onset of stroke and not 4.5 h after stroke. In great contrast, activation of NR2A-mediated cell survival signaling with administration of either glycine alone or in the presence of NR2B antagonist significantly attenuated ischemic brain damage even when delivered 4.5 h after stroke onset. Together, the present work provides a molecular basis for the dual roles of NMDA receptors in promoting neuronal survival and mediating neuronal damage and suggests that selective enhancement of NR2A-containing NMDA receptor activation with glycine may constitute a promising therapy for stroke.

Ischemic tolerance and endogenous neuroprotection

Practically any stimulus capable of causing injury to a tissue or organ can, when applied close to (but below) the threshold of damage, activate endogenous protective mechanisms--thus potentially lessening the impact of subsequent, more severe stimuli. A sub-threshold ischemic insult applied to the brain, for example, activates certain cellular pathways that can help to reduce damage caused by subsequent ischemic episodes--a phenomenon known as 'ischemic preconditioning' (IP) or 'ischemic tolerance' (IT). Although investigated for some time in model organisms, IP/IT has recently been shown in human brain. This opens a window into endogenous neuroprotection and, potentially, a window of opportunity to utilize these mechanisms in the clinic to treat patients with stroke and other CNS disorders.

Estrogen therapy in postmenopausal women: effects on cognitive function and dementia

CONTEXT

Several studies have suggested that estrogen replacement therapy in postmenopausal women improves cognition, prevents development of dementia, and improves the severity of dementia, while other studies have not found a benefit of estrogen use.

OBJECTIVE

To determine whether postmenopausal estrogen therapy improves cognition, prevents development of dementia, or improves dementia severity.

DATA SOURCES

We performed a literature search of studies published from January 1966 through June 1997, using MEDLINE, manually searched bibliographies of articles identified, and consulted experts.

STUDY SELECTION

Studies that evaluated biological mechanisms of estrogen's effect on the central nervous system and studies that addressed the effect of estrogen on cognitive function or on dementia.

DATA EXTRACTION

We reviewed studies for methods, sources of bias, and outcomes and performed a meta-analysis of the 10 studies of postmenopausal estrogen use and risk of dementia using standard meta-analytic methods.

DATA SYNTHESIS

Biochemical and neurophysiologic studies suggest several mechanisms by which estrogen may affect cognition: promotion of cholinergic and serotonergic activity in specific brain regions, maintenance of neural circuitry, favorable lipoprotein alterations, and prevention of cerebral ischemia. Five observational studies and 8 trials have addressed the effect of estrogen on cognitive function in nondemented postmenopausal women. Cognition seems to improve in perimenopausal women, possibly because menopausal symptoms improve, but there is no clear benefit in asymptomatic women. Ten observational studies have measured the effect of postmenopausal estrogen use on risk of developing dementia. Meta-analysis of these studies suggests a 29% decreased risk of developing dementia among estrogen users, but the findings of the studies are heterogeneous. Four trials of estrogen therapy in women with Alzheimer disease have been conducted and have had primarily positive results, but most have been small, of short duration, non-randomized, and uncontrolled.

CONCLUSIONS

There are plausible biological mechanisms by which estrogen might lead to improved cognition, reduced risk for dementia, or improvement in the severity of dementia. Studies conducted in women, however, have substantial methodologic problems and have produced conflicting results. Large placebo-controlled trials are required to address estrogen's role in prevention and treatment of Alzheimer disease and other dementias. Given the known risks of estrogen therapy, we do not recommend estrogen for the prevention or treatment of Alzheimer disease or other dementias until adequate trials have been completed.

A peptide inhibitor of c-Jun N-terminal kinase protects against excitotoxicity and cerebral ischemia

Neuronal death in cerebral ischemia is largely due to excitotoxic mechanisms, which are known to activate the c-Jun N-terminal kinase (JNK) pathway. We have evaluated the neuroprotective power of a cell-penetrating, protease-resistant peptide that blocks the access of JNK to many of its targets. We obtained strong protection in two models of middle cerebral artery occlusion (MCAO): transient occlusion in adult mice and permanent occlusion in 14-d-old rat pups. In the first model, intraventricular administration as late as 6 h after occlusion reduced the lesion volume by more than 90% for at least 14 d and prevented behavioral consequences. In the second model, systemic delivery reduced the lesion by 78% and 49% at 6 and 12 h after ischemia, respectively. Protection correlated with prevention of an increase in c-Jun activation and c-Fos transcription. In view of its potency and long therapeutic window, this protease-resistant peptide is a promising neuroprotective agent for stroke.

Guglielmi detachable coil embolization of acute intracranial aneurysm: perioperative anatomical and clinical outcome in 403 patients

From December 1990 to July 1995, the investigators participated in a prospective clinical study to evaluate the safety of the Guglielmi detachable coil (GDC) system for the treatment of aneurysms. This report summarizes the perioperative results from eight initial interventional neuroradiology centers in the United States. The report focuses on 403 patients who presented with acute subarachnoid hemorrhage from a ruptured intracranial aneurysm. These patients were treated within 15 days of the primary intracranial hemorrhage and were followed until they were discharged from the hospital or died. Seventy percent of the patients were female and 30% were male. The patients' mean age was 58 years old. Aneurysm size was categorized as small (60.8%), large (34.7%), and giant (4.5%); and neck size was categorized as small (53.6%), wide (36.2%), fusiform (6%), and undetermined (4.2%). Fifty-seven percent of the aneurysms were located in the posterior circulation and 43% in the anterior circulation. Eighty-two patients were classified as Hunt and Hess Grade I (20.3%), 105 Grade II (26.1%), 121 Grade III (30%), 69 Grade IV (17.1%), and 26 Grade V (6.5%). All patients in this study were excluded from surgical treatment either because of anticipated surgical difficulty (69.2%), attempted and failed surgery (12.7%), the patient's poor neurological (12.2%) or medical (4.7%) status, and/or refusal of surgery (1.2%). The GDC embolization was performed within 48 hours of primary hemorrhage in 147 patients (36.5%), within 3 to 6 days in 156 patients (38.7%), 7 to 10 days in 71 patients (17.6%), and 11 to 15 days in 29 patients (7.2%). Complete aneurysm occlusion was observed in 70.8% of small aneurysms with a small neck, 35% of large aneurysms, and 50% of giant aneurysms. A small neck remnant was observed in 21.4% of small aneurysms with a small neck, 57.1% of large aneurysms, and 50% of giant aneurysms. Technical complications included aneurysm perforation (2.7%), unintentional parent artery occlusion (3%), and untoward cerebral embolization (2.48%). There was a 8.9% immediate morbidity rate related to the GDC technique. Seven deaths were related to technical complications (1.74%) and 18 (4.47%) to the severity of the primary hemorrhage. The findings of this study demonstrate the safety of the GDC system for the treatment of ruptured intracranial aneurysms in anterior and posterior circulations. The authors believe additional randomized studies will further identify the role of this technique in the management of acutely ruptured incranial aneurysms.

An analysis of the lowest effective intensity of prophylactic anticoagulation for patients with nonrheumatic atrial fibrillation

BACKGROUND

To avert major hemorrhage, physicians need to know the lowest intensity of anticoagulation that is effective in preventing stroke in patients with atrial fibrillation. Since the low rate of stroke has made it difficult to perform prospective studies to resolve this issue, we conducted a case-control study.

METHODS

We studied 74 consecutive patients with atrial fibrillation who were admitted to our hospital from 1989 through 1994 after having an ischemic stroke while taking warfarin. For each patient with stroke, three controls with nonrheumatic atrial fibrillation who were treated as outpatients were randomly selected from the 1994 registry of the anticoagulant-therapy unit (222 controls). We used the international normalized ratio (INR) to measure the intensity of anticoagulation. For the patients with stroke, we used INR at admission; for the controls, we selected the INR that was measured closest to the month and day of the matched case patient's hospital admission.

RESULTS

The risk of stroke rose steeply at INRs below 2.0. At an INR of 1.7, the adjusted odds ratio for stroke, as compared with the risk at an INR of 2.0, was 2.0 (95 percent confidence interval, 1.6 to 2.4); at an INR of 1.5, it was 3.3 (95 percent confidence interval, 2.4 to 4.6); and at an INR of 1.3, it was 6.0 (95 percent confidence interval, 3.6 to 9.8). Other independent risk factors were previous stroke (odds ratio, 10.4; 95 percent confidence interval, 4.4 to 24.5), diabetes mellitus (odds ratio, 2.95; 95 percent confidence interval, 1.3 to 6.5), hypertension (odds ratio, 2.5; 95 percent confidence interval, 1.1 to 5.7), and current smoking (odds ratio, 5.7; 95 percent confidence interval, 1.4 to 24.0).

CONCLUSIONS

Among patients with atrial fibrillation, anticoagulant prophylaxis is effective at INRs of 2.0 or greater. Since previous studies have indicated that the risk of hemorrhage rises rapidly at INRs greater than 4.0 to 5.0, tight control of anticoagulant therapy to maintain the INR between 2.0 and 3.0 is a better strategy than targeting lower, less effective levels of anticoagulation.

Physical activity and stroke risk: a meta-analysis

BACKGROUND AND PURPOSE

Whether physical activity reduces stroke risk remains controversial. We used a meta-analysis to examine the overall association between physical activity or cardiorespiratory fitness and stroke incidence or mortality.

METHODS

We searched MEDLINE from 1966 to 2002 and identified 23 studies (18 cohort and 5 case-control) that met inclusion criteria. We estimated the overall relative risk (RR) of stroke incidence or mortality for highly and moderately active individuals versus individuals with low levels of activity using the general variance-based method.

RESULTS

The meta-analysis documented that there was a reduction in stroke risk for active or fit individuals compared with inactive or unfit persons in cohort, case-control, and both study types combined. For cohort studies, highly active individuals had a 25% lower risk of stroke incidence or mortality (RR=0.75; 95% CI, 0.69 to 0.82) compared with low-active individuals. For case-control studies, highly active individuals had a 64% lower risk of stroke incidence (RR=0.36; 95% CI, 0.25 to 0.52) than their low-active counterparts. When we combined both the cohort and case-control studies, highly active individuals had a 27% lower risk of stroke incidence or mortality (RR=0.73; 95% CI, 0.67 to 0.79) than did low-active individuals. We observed similar results in moderately active individuals compared with inactive persons (RRs were 0.83 for cohort, 0.52 for case-control, and 0.80 for both combined). Furthermore, moderately and highly active individuals had lower risk of both ischemic and hemorrhagic strokes than low-active individuals.

CONCLUSIONS

We conclude that moderate and high levels of physical activity are associated with reduced risk of total, ischemic, and hemorrhagic strokes.

Carotid endarterectomy and prevention of cerebral ischemia in symptomatic carotid stenosis. Veterans Affairs Cooperative Studies Program 309 Trialist Group

OBJECTIVE

To determine whether carotid endarterectomy provides protection against subsequent cerebral ischemia in men with ischemic symptoms in the distribution of significant (greater than 50%) ipsilateral internal carotid artery stenosis.

DESIGN

Prospective, randomized, multicenter trial.

SETTING

Sixteen university-affiliated Veterans Affairs medical centers.

PATIENTS

Men who presented within 120 days of onset of symptoms that were consistent with transient ischemic attacks, transient monocular blindness, or recent small completed strokes between July 1988 and February 1991. Among 5000 patients screened, 189 individuals were randomized with angiographic internal carotid artery stenosis greater than 50% ipsilateral to the presenting symptoms. Forty-eight eligible patients who refused entry were followed up outside of the trial.

OUTCOME MEASURES

Cerebral infarction or crescendo transient ischemic attacks in the vascular distribution of the original symptoms or death within 30 days of randomization.

INTERVENTION

Carotid endarterectomy plus the best medical care (n = 91) vs the best medical care alone (n = 98).

RESULTS

At a mean follow-up of 11.9 months, there was a significant reduction in stroke or crescendo transient ischemic attacks in patients who received carotid endarterectomy (7.7%) compared with nonsurgical patients (19.4%), or an absolute risk reduction of 11.7% (P = .011). The benefit of surgery was more profound in patients with internal carotid artery stenosis greater than 70% (absolute risk reduction, 17.7%; P = .004). The benefit of surgery was apparent within 2 months after randomization, and only one stroke was noted in the surgical group beyond the 30-day perioperative period.

CONCLUSIONS

For a selected cohort of men with symptoms of cerebral or retinal ischemia in the distribution of a high-grade internal carotid artery stenosis, carotid endarterectomy can effectively reduce the risk of subsequent ipsilateral cerebral ischemia. The risk of cerebral ischemia in this subgroup of patients is considerably higher than previously estimated.

Pooling of animal experimental data reveals influence of study design and publication bias

BACKGROUND AND PURPOSE

The extensive neuroprotective literature describing the efficacy of candidate drugs in focal ischemia has yet to lead to the development of effective stroke treatments. Ideally, the choice of drugs taken forward to clinical trial should be based on an unbiased assessment of all available data. Such an assessment might include not only the efficacy of a drug but also the in vivo characteristics and limits--in terms of time window, dose, species, and model of ischemia used--to that efficacy. To our knowledge, such assessments have not been made. Nicotinamide is a candidate neuroprotective drug with efficacy in experimental stroke, but the limits to and characteristics of that efficacy have not been fully described.

METHODS

Systematic review and modified meta-analysis of studies of experimental stroke describing the efficacy of nicotinamide. The search strategy ensured ascertainment of studies published in full and those published in abstract only. DerSimonian and Laird random effects meta-analysis was used to account for heterogeneity between studies.

RESULTS

Nicotinamide improved outcome by 0.287 (95% confidence interval 0.227 to 0.347); it was more effective in temporary ischemia models, after intravenous administration, in animals without comorbidities, and in studies published in full rather than in abstract. Studies scoring highly on a quality measure gave more precise estimates of the global effect.

CONCLUSIONS

Meta-analysis provides an effective technique for the aggregation of data from experimental stroke studies. We propose new standards for reporting such studies and a systematic approach to aggregating data from the neuroprotective literature.

Warfarin and aspirin in patients with heart failure and sinus rhythm

BACKGROUND

It is unknown whether warfarin or aspirin therapy is superior for patients with heart failure who are in sinus rhythm.

METHODS

We designed this trial to determine whether warfarin (with a target international normalized ratio of 2.0 to 3.5) or aspirin (at a dose of 325 mg per day) is a better treatment for patients in sinus rhythm who have a reduced left ventricular ejection fraction (LVEF). We followed 2305 patients for up to 6 years (mean [±SD], 3.5±1.8). The primary outcome was the time to the first event in a composite end point of ischemic stroke, intracerebral hemorrhage, or death from any cause.

RESULTS

The rates of the primary outcome were 7.47 events per 100 patient-years in the warfarin group and 7.93 in the aspirin group (hazard ratio with warfarin, 0.93; 95% confidence interval [CI], 0.79 to 1.10; P=0.40). Thus, there was no significant overall difference between the two treatments. In a time-varying analysis, the hazard ratio changed over time, slightly favoring warfarin over aspirin by the fourth year of follow-up, but this finding was only marginally significant (P=0.046). Warfarin, as compared with aspirin, was associated with a significant reduction in the rate of ischemic stroke throughout the follow-up period (0.72 events per 100 patient-years vs. 1.36 per 100 patient-years; hazard ratio, 0.52; 95% CI, 0.33 to 0.82; P=0.005). The rate of major hemorrhage was 1.78 events per 100 patient-years in the warfarin group as compared with 0.87 in the aspirin group (P<0.001). The rates of intracerebral and intracranial hemorrhage did not differ significantly between the two treatment groups (0.27 events per 100 patient-years with warfarin and 0.22 with aspirin, P=0.82).

CONCLUSIONS

Among patients with reduced LVEF who were in sinus rhythm, there was no significant overall difference in the primary outcome between treatment with warfarin and treatment with aspirin. A reduced risk of ischemic stroke with warfarin was offset by an increased risk of major hemorrhage. The choice between warfarin and aspirin should be individualized. (Funded by the National Institute of Neurological Disorders and Stroke; WARCEF ClinicalTrials.gov number, NCT00041938.).