Cochrane review: Dipyridamole for preventing major vascular events in patients with vascular disease

Background - Patients enrolled in clinical trials after nondisabling cerebral ischemia have an annual risk of vascular events ( death from all vascular causes, nonfatal stroke, or nonfatal myocardial infarction) of 4% to 11%. Aspirin reduces the incidence by 13%. Many trials in patients presenting with vascular disease investigated the efficacy of ( addition of) dipyridamole in secondary prevention. We systematically compared the efficacy and safety of dipyridamole versus control in the presence and absence of other antiplatelet drugs in clinical trials on the secondary prevention of vascular events in patients with vascular disease. Summary of Review - Randomized trials with concealed treatment allocation in patients with a nonembolic arterial vascular disease were selected. Therapy consisted of dipyridamole in the presence or absence of other antiplatelet drugs compared with no drug or an antiplatelet drug(s) other than dipyridamole. Twenty-six trials were included, with a total of 19 842 patients. Dipyridamole was not more efficacious in the prevention of vascular death ( relative risk [RR], 1.02; 95% CI, 0.90 to 1.17). It appeared more efficacious in the prevention of vascular events ( RR, 0.90; 95% CI, 0.83 to 0.98), but this result only reached statistical significance because of 1 large trial in patients presenting with cerebral ischemia. Combination treatment of dipyridamole and aspirin compared with aspirin had an RR of 1.03 ( 95% CI, 0.87 to 1.22) for vascular death and an RR of 0.90 ( 95% CI, 0.80 to 1.00) for vascular events. Conclusions - For patients who presented with arterial vascular disease, there was no evidence that dipyridamole, in the presence or absence of another antiplatelet drug ( chiefly aspirin), reduced the risk of vascular death, although it may reduce the risk of further vascular events. However, this benefit was found only in a single large trial and only in patients presenting after cerebral ischemia. There was no evidence that dipyridamole alone was more efficacious than aspirin. Further trials comparing the effects of the combination of dipyridamole plus aspirin with aspirin alone are justified.