When a thrombus forms within an artery, this is known as an arterial thrombosis. Arterial thrombi usually develop on top of an atherosclerotic plaque and cause myocardial infarction (MI), unstable angina, ischaemic stroke and some manifestations of peripheral arterial disease, such as acute limb ischaemia. Risk factors for arterial thrombosis include smoking, obesity, high blood pressure, increasing age, diabetes and family history. The incidence and prevalence of the clinical manifestations of arterial thrombosis is high. The annual incidence of symptomatic and fatal MI and stroke in the United States (US) in 2010 has been calculated to be 915,000 and 795,000 cases, respectively.