Anticoagulant therapy after acute myocardial infarction

The use of anticoagulant therapy for patients who have had an acute myocardial infarction is still controversial, mainly because early major studies had conflicting findings, but reanalysis of the data did produce evidence that anticoagulation had clinically and statistically significant benefits. Now more evidence, including the results of a 10-day in-hospital study of low- and high-dose calcium heparin, has been gathered to support using anticoagulants for these patients. The study used the development of left ventricular mural thrombosis, a frequent complication of acute myocardial infarction that carries a high risk for systemic embolic complications, to assess clinical outcome: A reduced incidence of mural thrombosis would be taken to indicate reduced chances that patients would have major systemic emboli. Two-dimensional echocardiography was used to detect thrombi. In the study, the incidence of left ventricular mural thrombosis was significantly lower in the high--than in the low-dose group. Among patients in the high-dose group in whom a mural thrombosis did develop, plasma heparin concentrations were significantly lower and activated partial thromboplastin times were shorter. These data suggest that monitoring plasma heparin levels and anticoagulant response can ensure maximal treatment effectiveness. No significant differences in other outcomes--such as bleeding complications, nonhemorrhagic strokes and mortality--were found between the high- and low-dose treatment groups.