The benefits and risks of oral antiplatelet therapy

The authors conducted a review of oral antiplatelet therapy in patients with acute ischemic stroke.

In people with acute ischemic stroke, platelets (small cell fragments in the blood) become activated and can cause blood clots to form and block an artery in the brain, resulting in damage to part of the brain. Such damage gives rise to the symptoms of stroke. Antiplatelet therapy involves using drugs that stop blood cells from sticking together and forming a blood clot. This might reduce the volume of brain damaged by ischemia and also reduce the risk of early recurrent (returning) ischemic stroke, thereby reducing the risk of early death and improving long-term outcomes in survivors. However, antiplatelet therapy might also increase the risk of fatal or disabling intracranial hemorrhage (bleeding that occurs inside the skull).

The authors of this article aimed to assess the effectiveness and safety of immediate oral antiplatelet therapy in people with acute ischemic stroke.

This review analyzed randomized trials comparing oral antiplatelet therapy (started within 14 days of the stroke) with control in people with definite or presumed ischemic stroke. The review included 8 trials with 41,483 patients. Four studies analyzed aspirin, three analyzed ticlopidine (Ticlid) and one analyzed aspirin plus dipyridamole (Persantine). Two trials testing aspirin 160 mg to 300 mg once daily, started within 48 hours of onset, contributed 98% of the data. The maximum follow-up was 6 months.

Antiplatelet therapy was associated with an 8% reduction in the odds of death during treatment and a 5% reduction in the odds of death or dependence (needing help with daily activities or living in an institution) at final follow-up. For aspirin, for every 1000 people treated, 13 would avoid death or dependence. A subgroup analysis of a subset of patients in whom the initial stroke was due to intracerebral hemorrhages (burst blood vessels in the brain, allowing blood to leak into the brain) showed that the odds of poor outcome were 32% lower in those allocated to aspirin.

The odds of pulmonary embolism (sudden blockage of a blood vessel in the lung, usually by a blood clot) were significantly reduced by 29% in patients undergoing antiplatelet therapy. Antiplatelet therapy (chiefly aspirin) was also associated with a 23% reduction in the odds of recurrent ischemic stroke. However, antiplatelet therapy was also associated with a significant 23% increase in the risk of symptomatic intracranial hemorrhage. Allocation to antiplatelet therapy was associated with a 69% increase in the risk of major extracranial hemorrhage (a collection of blood outside the skull).

The authors stated that the review provided strong evidence for the benefits of aspirin 160 to 300 mg, given as soon as is practical (and continued as a once daily dose), in people with suspected acute ischemic stroke.