Primary and secondary prevention of arterial thromboembolism.

Abstract

Aspirin in doses of approximately 300 mg/day may be recommended for the primary prevention of myocardial infarction in males and probably also in females, but only in those individuals with a moderate to high risk of cardiovascular disease. In patients with stable angina, aspirin decreases the risk for a first myocardial infarction. Aspirin or ticlopidine should be given to patients with unstable angina, in conjunction with heparin in the most severe cases. Long-term oral anticoagulant treatment after myocardial infarction in low risk patients has a limited effect on mortality but reduces the incidence of non-fatal recurrent myocardial infarction and stroke. Daily aspirin is more convenient and simple, and is at least as effective, but associated with a lower risk of bleeding. The concurrent use of aspirin and low intensity anticoagulation in the secondary prevention of myocardial infarction has, however, not been investigated. Various antiplatelet agents, including aspirin (alone or combined with dipyridamole) and ticlopidine, have, in contrast to oral anticoagulants, proved useful in the prevention of early thrombosis in aorto-coronary grafts, provided treatment begins at the latest 6 h after surgery. The usefulness of antiplatelet drugs has been well established in the prevention of immediate reocclusion following coronary angioplasty, but so far no drugs can prevent late restenosis. In patients with a synthetic cardiac valve prosthesis, lifelong treatment with coumarins is still indispensable, but their antithrombotic effect can be reinforced by dipyridamole or aspirin which also allows to reduce the intensity of anticoagulation. In uncomplicated bioprosthetic valve replacement, low intensity anticoagulation during the first 3 months suffices. Diuretics probably provide the best primary protection against cerebrovascular accidents in moderate hypertensives, although medium doses of aspirin may be considered in elderly people at high risk of such accidents. Aspirin (alone or combined with dipyridamole) and ticlopidine may be recommended for the secondary prevention of cerebral ischaemic accidents. Aspirin and ticlopidine, but not oral anticoagulants, reinforce the treatment of obliterative arterial disease in the lower limbs.