Dipyridamole for preventing stroke and other vascular events in patients with vascular disease.

Patients with transient ischaemic attacks (TIA) and minor ischaemic strokes are at risk of serious vascular events (death from all vascular causes, non-fatal stroke, or non-fatal myocardial infarction). Their risk of vascular events lies between 4 and 11 percent per year. Aspirin only, in a daily dose of 30 mg or more, offers only modest protection in such patients: it reduces the incidence of major vascular events by 13 percent. In a single trial, adding dipyridamole (an alternative antiplatelet agent) to aspirin was associated with a 22 percent reduction in the risk of major vascular events compared with aspirin alone. However, a systematic review of all trials of antiplatelet agents by the Antithrombotic Trialists' Collaboration showed that, in high risk patients, there was virtually no difference between the aspirin-dipyridamole combination and aspirin alone. We therefore sought to assess the effects of dipyridamole in more detail.