The authors studied 80 consecutive patients with a first Q wave anterior myocardial infarction (MI) by 2-dimensional and color Doppler echocardiography (echo), on day 3 and day 10 after admission, to determine whether left ventricular (LV) blood flow dynamics differ between those who develop LV thrombus and those who do not. With pulsed Doppler echo, peak flow velocities were measured in diastole at the inflow tract, at the apex in diastole and systole, and at the outflow tract in systole. There were 11 patients (14%) who had LV thrombosis on day 3. On day 10, no other patient developed a thrombus. There was no difference in the Doppler flow velocities, except for lower apical diastolic velocities (0.23 +/- 0.04 m/s) (+/- SEM) in patients with thrombus as compared with those without it (0.33 +/- 0.01 m/s) (p less than 0.05). All patients with thrombus had apical dyskinesis and 8 (73%) had an anteroapical aneurysm, while 40 (58%) patients without thrombosis had dyskinesis and 11 (16%) had an aneurysm (p less than 0.01). The ejection fraction was lower (25.4 +/- 3.2%), the wall motion score was higher (10.6 +/- 0.7), and mitral regurgitation was seen more frequently (45%) in those with LV thrombus (respective values in no thrombus group patients: 32.9 +/- 1.4%, 7.6 +/- 0.3, 7%). The authors conclude that LV thrombus prediction is difficult by Doppler flow velocity study, whereas dyskinesis and aneurysmal dilatation of the LV apex is significantly associated with thrombus.