Antiplatelet therapy for the primary and secondary prevention of cerebrovascular events in patients with extracranial carotid artery disease

Cerebrovascular disease is a leading cause of morbidity and mortality in developed countries around the world. In the United States, there are an estimated 700,000 cases of stroke annually (of which over 85% are ischemic), costing an estimated $56.8 billion in associated treatment. Large vessel internal carotid artery stenosis is an important cause of ischemic stroke. Population-based studies have shown that the prevalence of carotid stenosis is ∼0.5% in the sixth decade of life and increases to ∼10% in the ninth decade. The majority of patients are asymptomatic. Asymptomatic carotid stenosis with ≤75% lumen loss carries a stroke risk of 1.3% annually, whereas the combined risk of myocardial ischemia and vascular death is as high as 10%. With diameter stenosis >75%, the combined stroke and transient ischemic attack risk increases to ∼11% annually, with 75% of events ipsilateral to the affected artery. Other studies have also shown that the risk of stroke increases proportionately to the severity of stenosis. The risk is higher for those patients who are symptomatic. In this review, we will discuss antiplatelet agents to prevent cerebrovascular events in the context of extracranial carotid artery disease. It is beyond the scope of this article to discuss antiplatelet treatment for other etiologies of stroke.