Prevention of
stroke is a crucial health care issue, as
stroke is the third cause of death and the first cause of major disability in developed countries. The established role of platelet aggregation in TIA or minor and major
ischaemic stroke has provided the rationale for many randomized trials of
antiplatelet agents (
aspirin,
sulfinpyrazone,
dipyridamole alone or in combination with
aspirin,
suloctidil,
ticlopidine). The recent Antiplatelet Trialists' Collaboration (
APT) meta-analysis (1994) based on 142 trials involving 100,000 vascular patients confirmed the data of the previous overview (1988).
Aspirin, the only
drug evaluated for primary prevention of ischaemic events, is not indicated for safety reasons in subjects at low risk of occlusive disease. Compared to control, antiplatelet
therapy, notably
aspirin which is by far the most widely used agent in trials, provides a 27% risk reduction of
stroke,
myocardial infarction or vascular death in patients suffering from ischaemic vascular events and a 22% risk reduction of these outcomes in patients having experienced a prior TIA/
stroke.
Aspirin (around 325 mg/day) and
ticlopidine (500 mg/day) are currently the reference drugs for
secondary prevention in cerebrovascular patients. The long term efficacy of
ticlopidine, a specific antiaggregating agent, has been evaluated in two North American trials involving more than 4,000 patients. TASS showed
ticlopidine to be significantly more effective in reducing the incidence of fatal or nonfatal
stroke and death than
aspirin in patients with TIA or minor
stroke. The relative risk reductions over
aspirin, the first year of greatest risk, were 41% for
stroke and death and 46% for fatal or nonfatal
stroke. CATS showed that
ticlopidine compared with placebo induces a significant 30% relative risk reduction of
stroke,
myocardial infarction and vascular death over three years in patients who had suffered a recent thromboembolic
stroke. The above results elicit two important issues: the optimal dose of
aspirin and its tolerability compared to
ticlopidine. The three controlled trials (UK-TIA,
SALT, Dutch TIA) which have compared high (> or = 1 g/day) and low dose
aspirin (< or = 300 mg/day) or various low doses of
aspirin did not give a definite answer on the efficacy of low or very low (30 or 75 mg/day) doses of
aspirin for reducing the risk of vascular outcomes in patients with
stroke precursors. Even with low doses of
aspirin there was still a risk of severe gastrointestinal
bleeding, although minor side effects were less frequent.(ABSTRACT TRUNCATED AT 400 WORDS)