Anticoagulants for Preventing Stroke in Patients With Nonrheumatic Atrial Fibrillation and a History of Stroke or Transient Ischemic Attack
People with nonrheumatic atrial fibrillation (NRAF) who have had a transient ischemic attack (TIA) or a minor ischemic stroke are at high risk of recurrent stroke.
The objective of this review was to assess the effect of anticoagulants for secondary prevention in patients with NRAF after a stroke or TIA.
This review has drawn on the search strategy developed for the Stroke Group as a whole. Relevant trials were identified in the Stroke Group Trials Register (last search June 9, 2003). We also contacted researchers in the field to identify further published and unpublished studies.
Randomized trials comparing oral anticoagulants with control (no therapy) or placebo in patients with NRAF and a previous TIA or minor ischemic stroke were selected. Control groups on aspirin did not meet the selection criteria.
Data Collection and Analysis
Both reviewers assessed trial quality and extracted data. The main outcomes considered were: (1) fatal or nonfatal recurrent stroke; (2) all major vascular events: vascular death (including fatal bleeds), recurrent stroke (both ischemic and hemorrhagic), myocardial infarction, and systemic embolism; (3) any intracranial bleed; (4) major extracranial bleed.
Two trials involving 485 patients were included. Follow-up time was 1.7 years in 1 trial and 2.3 years in the other. Anticoagulants reduced the odds of recurrent stroke by two thirds (odds ratio [OR] 0.36, 95% confidence interval [CI] 0.22 to 0.58). The odds of all vascular events were shown to be almost halved by treatment (OR 0.55, 95% CI 0.37 to 0.82). The odds of major extracranial hemorrhage was increased (OR 4.32, 95% CI 1.55 to 12.10). No intracranial bleeds were reported among patients given anticoagulants.
Implications for Practice
The results of this review are based on 2 trials, EAFT and VA-SPINAF, and imply that anticoagulants should be prescribed to patients with NRAF and a recent TIA or minor ischemic stroke, unless there is a major contraindication. Other evidence suggests that the target value for the INR should be set between 2.0 and 3.0. (Figure)
Implications for Research
(1) There remains uncertainty about the ideal timing of initiating anticoagulant therapy. Acute therapy with low-molecular-weight-heparin or unfractionated heparin does not appear to be beneficial, the modest benefits being outweighed by the modest risks. It is generally recommended that oral anticoagulation be initiated 1 to 2 weeks after stroke onset.
(2) The results do not definitively answer the question of how long antithrombotic treatment should be continued. The available data suggest that both anticoagulant and aspirin treatment should be given for as long as possible, ie, until a contraindication occurs.
Anticoagulants are beneficial and carry no serious adverse effects for people with NRAF and recent cerebral ischemia.
Note: The full text of this review is available in the Cochrane Library (for subscribers: www.update-software.com/Cochrane). The full article should be cited as: Saxena R, Koudstaal PJ. Anticoagulants for preventing stroke in patients with nonrheumatic atrial fibrillation and a history of stroke or transient ischemic attack [Cochrane Review]. In: The Cochrane Library, Issue 2, 2004. Oxford: Update Software. © Cochrane Library, John Wiley & Sons Ltd.
Section Editor: Graeme J. Jankey, MD, FRACP
- Received March 23, 2004.
- Accepted March 30, 2004.