The goals of this study were to assess the serial change in coronary blood flow velocity (CBFV) patterns with transthoracic Doppler echocardiography and to decide optimal timing to predict left ventricular (LV) remodeling in patients with anterior acute myocardial infarction. We recorded CBFV of the left anterior descending (LAD) coronary artery with transthoracic Doppler echocardiography and measured diastolic deceleration time (DDT, measured in milliseconds) on days 2, 7, and 21 in 52 patients with anterior acute myocardial infarction treated with primary coronary angioplasty. On day 2, DDT was >/=600 ms in 21 patients (group A) and <600 ms in the other 31 patients (group B). In group B, DDT increased to >/=600 ms in 12 patients on day 7 (group B1), and DDT was still <600 ms in the other 19 patients (group B2). However, DDT became comparable among 3 groups on day 21. Group B2 patients had significant chronic LV dilation (LV end-diastolic volume index in groups A, B1, and B2 at 6 months: 74 +/- 16 vs 81 +/- 17 vs 100 +/- 22. ml/m(2), respectively; p <0.05 vs other groups). Multivariate analysis revealed that DDT <600 ms on day 7 was the only independent variable related to LV remodeling. In conclusion, the CBFV pattern changed toward normalization with time in patients with acute myocardial infarction. Time taken for normalization varied among patients. Persistence of microvascular dysfunction up to 7 days after reperfusion predicted LV remodeling.