Heparin after acute myocardial infarction.

Heparin is commonly, but by no means universally, used after acute myocardial infarction. When used the dose, route of administration, and duration of therapy varies considerably. The role of heparin is reviewed with particular reference to its use in conjunction with other commonly used therapies, such as aspirin and thrombolytic agents. Intravenous heparin after thrombolytic therapy remains untested in patients treated with aspirin. When used, benefit is seen in a narrow aPTT range, and there have been unexpected increases in mortality in patients with the greatest heparin effect. The addition of delayed subcutaneous heparin to aspirin and thrombolytic therapy does not provide a mortality benefit. In patients not treated with thrombolysis, there is no clear evidence that heparin confers significant mortality benefit if patients are treated with aspirin. Heparin therapy may reduce the incidence of intraventricular thrombus after anterior wall infarction, but there is no clear evidence that it reduces the clinically important sequelae of cerebral embolism and stroke. Given concerns about increased hemorrhagic rates with heparin and unknown benefit, it is reasonable to conclude that its role in the management of patients with acute myocardial infarction remains unclear.