Heparin and secondary prevention of acute myocardial infarction.

Patients surviving acute myocardial infarction (AMI) may experience several clinical events (reinfarction, congestive heart failure, sudden death) still responsible for high mortality rates. AMI early complicated by residual angina, left ventricular dysfunction, or malignant arrhythmias has a worse prognosis. Secondary prevention of myocardial infarction and death has been the end point of many clinical trials in the past two decades. It is well known that beta blockers prevent sudden death if administered chronically after AMI. Meta-analysis of controlled randomized trials demonstrated a significant reduction in reinfarction and vascular death with long-term antiplatelet treatment. Oral anticoagulants prevent fatal and non-fatal reinfarction and show a trend towards lower mortality rates, though treated patients have a higher incidence of haemorrhagic events, particularly stroke. Early administration of heparin gave contradictory results on short-term prevention of myocardial infarction and death after AMI. Data on long-term heparin therapy point out a significant reduction in recurrent AMI and a trend towards a decrease in general mortality.