Left ventricular thrombus formation and resolution in acute myocardial infarction.

Left ventricular thrombus formation and resolution were studied by serial echocardiography in 38 patients with acute anterior myocardial infarction. Twenty (52.6%) patients developed thrombus. Cumulative rates were: 12/20 (60%) at 24 h (+/-24 h), 17/20 (85%) at 72 h (+/-24 h), and 19/20 (95%) at 120 h (+/-24 h). Early thrombus formation was associated with worse left ventricular wall motion relative to those with delayed thrombus development (P=0.00016). In patients with initially normal echocardiograms, subsequent thrombus formation was associated with wall motion deterioration (P=0.016). A thrombus occurred in 16/28 (57.1%) patients given streptokinase. Heparin and warfarin were given in case of thrombus formation. Among survivors with thrombus, resolution occurred with a cumulative rate of 1/18 (5.6%) at 72 h (+/-24 h), 2/18 (11.1%) at 120 h (+/-24 h), 10/18 (55.6%) at 3 months (+/-1 week) and 16/18 (88.9%) at 6 months (+/-1 week). No embolic events occurred. Left ventricular thrombus formation occurs often and early after acute anterior myocardial infarction, even when streptokinase is given. Delayed thrombus formation is associated with wall motion deterioration. Thrombus resolution occurs frequently during anticoagulation and seems not associated with increased embolic risk.