[Use of aspirin in coronary disease]

The beneficial effect of aspirin in different situations of coronary artery disease has been clearly demonstrated, but prescription remains empirical due to the lack of phase II trials and the incompletely understood mechanism of action. Since the ISIS-2 study was published in 1988, aspirin is indicated in the acute phase of myocardial infarction as mortality can be reduced by 20% and the rate of reocclusions reduced. The beneficial effect of aspirin in unstable angina has also been demonstrated with a reduction of more than 50% in the combined incidence of mortality and myocardial infarction. Stable angina is an ideal application for low-dose aspirin with an improvement in combined incidence of myocardial infarction and sudden death of 34%. The question of dose remains open. When prescribed for primary or secondary prevention, aspirin should be given at low-doses (50-100 mg/d) in a long-term regimen. The dose should be examined differently for treatment of acute thrombotic events including infarction and unstable angina. Doses above 250 mg/d with an initial dose of 500 mg to 1 g are recommended followed by a relay with 50 to 100 mg/d. Irreversible dose-dependent inhibition of platelet cyclooxygenase by aspirin is nearly total for a single dose of 100 mg. The effect is cumulative for smaller doses and since the anucleated platelets cannot resynthesize the enzyme only new platelet can recover enzymatic activity. The duration of the effect thus is a function of normal platelet turn-over (8 days). Currently, aspirin is indicated in all coronary artery patients and should be discussed for "potential" patients i.e. as primary prevention in healthy subjects at risk of coronary artery disease although the threshold of risk requiring prescription remains to be clearly determined.