Review Article
Antiplatelet Agents for Stroke Prevention Following Transient Ischemic Attack
Abstract
Regardless of extent or duration of acute effects, transient ischemic attack (TIA) is a marker for cerebrovascular ischemia and carries risk for secondary stroke comparable to that associated with ischemic stroke. Pharmacologic and nonpharmacologic interventions aimed at reducing risk of secondary stroke should be implemented as soon as possible after characterization of the initial event. Medical strategies for secondary prevention include modifying general cardiovascular risk factors but are centered on the specific reduction of stroke risk by antiplatelet agents. Aspirin and clopidogrel have each demonstrated efficacy in reducing secondary event risk; however, clopidogrel has not been shown specifically to prevent secondary events in patients who have had a TIA or stroke. Combination therapy using aspirin plus dipyridamole is the only combination approach to demonstrate additive benefit that is significantly greater than that conferred by aspirin. In contrast, the combination of clopidogrel plus aspirin has not demonstrated significant benefit over monotherapy with either agent and has been associated with increased risk of bleeding episodes.
Key Points
* Aspirin monotherapy has been shown to reduce risk of secondary events by 10% to 20% in patients who have had a transient ischemic attack (TIA) or stroke.
* Clopidogrel monotherapy has been shown to reduce risk of secondary vascular events by approximately 9% in patients with prior stroke or TIA, myocardial infarction, or peripheral arterial disease; however, no apparent benefit was demonstrated in stroke/TIA patients specifically.
* Combination therapy using aspirin plus dipyridamole is the only combination approach to demonstrate additive benefit that is significantly greater than that conferred by aspirin.
* The combination of clopidogrel plus aspirin has not demonstrated significant benefit over monotherapy with either agent and has been associated with an increased risk of bleeding episodes.
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