Background and Purpose--Trial data suggest that dipyridamole, with or without aspirin, is more efficacious in the secondary prevention of stroke than of coronary events. This selective effect might be attributed to blood pressure lowering by dipyridamole. Therefore, we aimed to assess the effect on blood pressure in the setting of a randomized clinical trial in patients with cerebral ischemia of presumed arterial origin.

Methods--In this study, 591 patients with recent cerebral ischemia of arterial origin were randomly allocated to treatment with aspirin 30 to 325 mg/d or with the combination of aspirin and dipyridamole 400 mg/d in the European/Australian Stroke Prevention in Reversible Ischemia Trial. In an on-treatment analysis, the change in blood pressure measurements from baseline to values after at least 6 months of follow up was assessed with linear regression analysis.

Results--After an average period of 15 months, systolic blood pressure dropped 6.2 mm Hg in the aspirin plus dipyridamole group (n=273) and 6.2 mm Hg in the aspirin group (n=318), for a difference of 0.0 mm Hg (95% confidence interval, -3.8 to 3.7). Diastolic blood pressure dropped 3.6 mm Hg in the aspirin plus dipyridamole group compared with 2.7 mm Hg in the aspirin group, for a difference of 0.9 mm Hg (95% confidence interval, -1.0 to 2.9).

Conclusions--It is unlikely that dipyridamole leads to a permanent reduction in blood pressure and that this would explain why this drug might prevent strokes rather than coronary events.