Anticoagulation and platelet antiaggregation therapy in stroke prevention

Abstract

The results of recent large clinical trials have modified treatment plans formerly based on inferred mechanisms of ischemic stroke and hazards of certain forms of therapy. Strong data have emerged to support anticoagulation with warfarin for stroke associated with inferred embolism in a setting of atrial fibrillation. No clear advantage for warfarin over aspirin exists for ischemic stroke in a setting of intracranial atheroma, patent cardiac foramen ovale, or elevated levels of antiphospholipid antibody. Among antiplatelet agents, aspirin and clopidogrel have a similar recurrent stroke risk. Combination therapies with aspirin and warfarin show no additional benefits with regard to stroke prevention and carry higher risks of hemorrhage. Treatment with aspirin combined with specially formulated long-acting dipyridamole carries a lower risk of stroke than aspirin alone and does not increase the risk of hemorrhage significantly. The combination of aspirin and clopidogrel does not reduce the risk of stroke over clopidogrel alone and carries a greater risk of bleeding than clopidogrel alone. Choice of antithrombotic therapy depends on the etiology of the stroke. Oral anticoagulation treatment is the preferred choice for inferred cardioembolism in the setting of atrial fibrillation, while the varying rates of hemorrhage with oral anticoagulants continue to favor antiplatelet therapy in other settings of inferred etiology. Combinations of antithrombotic therapy vary in their lowering of stroke rate, and some raise the risk of hemorrhage. Insufficient data exist to determine whether antithrombotic therapy combined with antihypertensives, statins or other agents will further reduce the risk of stroke in synergistic or supplemental fashion, or give no additional benefit.