Anticoagulants for preventing recurrence following presumed non‐cardioembolic ischaemic stroke or transient ischaemic attack
Abstract
Background
After a first ischaemic stroke, further vascular events due to thromboembolism (especially myocardial infarction and recurrent stroke) are common and often fatal. Anticoagulants could potentially reduce the risk of such events, but any benefits could be offset by an increased risk of fatal or disabling haemorrhages.
Objectives
To assess the effect of prolonged anticoagulant therapy (compared with placebo or open control) following presumed non‐cardioembolic ischaemic stroke or transient ischaemic attack.
Search methods
We searched the Cochrane Stroke Group trials register. We contacted companies marketing anticoagulant agents. The most recent search for this review was carried out in August 2002.
Selection criteria
Randomised and quasi‐randomised trials comparing at least one month of anticoagulant therapy with control in people with previous presumed non‐cardioembolic ischaemic stroke or transient ischaemic attack.
Data collection and analysis
Two review authors independently selected trials for inclusion, assessed trial quality and extracted the data.
Main results
Eleven trials involving 2487 participants were included. The quality of the nine trials which predated routine computerised tomography scanning and the use of the International Normalised Ratio to monitor anticoagulation was poor. There was no evidence of an effect of anticoagulant therapy on either the odds of death or dependency (two trials, odds ratio (OR) 0.83, 95% confidence interval (CI) 0.52 to 1.34) or of 'non‐fatal stroke, myocardial infarction, or vascular death' (four trials, OR 0.96, 95% CI 0.68 to 1.37). Death from any cause (OR 0.95, 95% CI 0.73 to 1.24) and death from vascular causes (OR 0.86, 95% CI 0.66 to 1.13) were not significantly different between treatment and control. The inclusion of two recent completed trials did not alter these conclusions. There was no evidence of an effect of anticoagulant therapy on the risk of recurrent ischaemic stroke (OR 0.85, 95% CI 0.66 to 1.09). However, anticoagulants increased fatal intracranial haemorrhage (OR 2.54, 95% CI 1.19 to 5.45), and major extracranial haemorrhage (OR 3.43, 95% CI 1.94 to 6.08). This is equivalent to anticoagulant therapy causing about 11 additional fatal intracranial haemorrhages and 25 additional major extracranial haemorrhages per year for every 1000 patients given anticoagulant therapy.
Authors' conclusions
Compared with control, there was no evidence of benefit from long‐term anticoagulant therapy in people with presumed non‐cardioembolic ischaemic stroke or transient ischaemic attack, but there was a significant bleeding risk.
PICOs
Plain language summary
Anticoagulants for preventing recurrence following presumed non‐cardioembolic ischaemic stroke or transient ischaemic attack
There is no evidence that stroke patients with a normal heart rhythm benefit from anticoagulants. Most strokes are due to a sudden blockage of an artery in the brain (this type of stroke is called an ischaemic stroke). In most ischaemic strokes, the blockage is caused by a blood clot. Anticoagulant drugs, such as warfarin, may prevent such clots forming and hence could prevent stroke. However, anticoagulant drugs may also cause bleeding in the brain and this complication could offset any benefits. This review identified 11 trials, in 2487 participants who had had a stroke, of anticoagulants to prevent further strokes. There was good evidence that anticoagulants could cause serious bleeding, and there was no evidence that anticoagulants were of benefit. However, other trials show that patients with an irregular heartbeat (atrial fibrillation) and a recent stroke due to a blocked artery do benefit from anticoagulants. New trials are underway to see whether stroke patients with a normal heart rhythm can get greater benefit from anticoagulants than from standard clot‐preventing treatments such as aspirin and other antiplatelet drugs.
