WARFARIN OR ASPIRIN AS SECONDARY PREVENTION OF ISCHEMIC STROKE

Until recently, the choice between aspirin (acetylsalicylic acid) or w arfarin for the secondary prevention of stroke was largely based on em pirical evidence. However, as stroke prevention trials have focused on patients with specific vascular pathologies, clearcut guidelines for the use of aspirin or warfarin are beginning to emerge. Warfarin is ge nerally considered first-line therapy in patients presenting with mino r stroke or transient ischaemic attack related to mitral stenosis, val vular atrial fibrillation, a mechanical prosthetic heart valve, acute myocardial infarction or cardiomyopathy. Several recent multicentre st udies suggest that warfarin is also the most effective drug far stroke prevention in patients with nonvalvular atrial fibrillation, unless t he patient is less than 65 years old and has lone atrial fibrillation, is older than 75 years, or is at high risk of haemorrhagic complicati ons. Aspirin is a safe and effective alternative choice in these setti ngs. There are no prospective studies comparing aspirin with warfarin in patients with symptomatic high grade stenosis of a major intracrani al artery. However, a recent retrospective multicentre study suggests that warfarin may reduce the risk of stroke, myocardial infarction or vascular death by almost 50% compared with aspirin in these patients. Ongoing studies will help to clarify whether warfarin or aspirin is su perior for preventing stroke in patients with intracranial penetrating artery disease, craniocervical arterial dissection, antiphospholipid antibodies or right-to-left interatrial shunts, and in patients with s troke of undetermined cause.