Prophylactic anticoagulation for left ventricular thrombi after acute myocardial infarction: a prospective randomized trial.

Thirty patients with a first episode of an anterior acute myocardial infarction (AMI) without a history of cardiac disease were prospectively randomized into a prophylactic heparin-treated group (group I) and a control nonanticoagulated group (group II) within 12 hours of the onset of chest pain to determine the effectiveness of anticoagulation for preventing left ventricular (LV) thrombi. Serial two-dimensional echocardiograms were performed during the hospital stay and patients were followed clinically for systemic emboli for 1 month after discharge from the hospital. Thirty-one percent of patients in group I (4/13) and 35% of patients in group II (6/17) developed LV thrombi on two-dimensional echocardiograms. There was no statistical difference in the incidence of LV thrombi between the two groups (p greater than 0.05). Infarct size as determined by creatine phosphokinase isoenzymes (2,386 +/- 1,568 vs 2,083 +/- 1,462 IU for groups I and II, respectively; p greater than 0.05), wall motion score (12.7 +/- 5 vs 10.7 +/- 5 for groups I and II, respectively; p greater than 0.05) and wall motion index (1.8 +/- 0.6 vs 1.8 +/- 0.56 for groups I and II, respectively; p greater than 0.05) were not statistically different between the two groups of patients. One patient in both groups had an embolic event. In conclusion, prophylactic anticoagulation in high-risk AMI patients for LV thrombus development does not prevent LV thrombus formation during the acute and subacute stages of an AMI. The results also suggest that anticoagulation may not prevent systemic embolization.