Serial two-dimensional echocardiography was performed in 23 patients with acute myocardial infarction who received intravenous thrombolytic therapy to evaluate the effect of acute reperfusion on regional wall motion abnormalities. Regional wall motion abnormalities improved in 4 of the 14 patients (29%) with successful reperfusion and in 1 of the 9 (11%) without successful reperfusion. In successfully reperfused patients, the main determinant of improvement in regional wall motion abnormalities was duration from the onset of chest pain to the time of reperfusion (3.3 vs. 6.3 h in successfully reperfused patients without recovery of regional wall motion abnormalities; P less than 0.001).