To evaluate the effects of early recanalization on left and right ventricular wall motion in acute myocardial infarction (AMI), we serially observed their degrees in 66 patients with AMI. The patients were categorized as Group 1:17 with spontaneous recanalization within 6 hours of onset of the chest pain; Group 2:34 with effective recanalization within 6 hours (10 by PTCR, 10 by PTCR+ PTCA, and 14 by direct PTCA), and Group 3:21 without effective recanalization. The Group 2 patients were classified in 3 subgroups according to the time intervals from onset of symptoms to recanalization; 11 patients with recanalization within 2 hours (Group 2a), 10 between 2 and 4 hours (Group 2b), and 13 between 4 and 6 hours (Group 2c). The left and right ventricular wall motion abnormality indexes (WMAI) were defined as the means of point scores for the degrees of regional wall motion abnormality at 11 segments of the left ventricle and seven segments of the right ventricle on serial two-dimensional echocardiograms. Results were as follows: 1. The LV-WMAI of Group 1 was smaller on day 1, and improved on day 28 as compared to those of the other groups (0.63 +/- 0.35 to 0.18 +/- 0.18, p less than 0.001). 2. The improvements of the LV-WMAI from days 1 to 28 in Group 2a (WMAI: 1.01 +/- 0.57 to 0.26 +/- 0.26, delta WMAI: 82 +/- 14%) and Group 2b (1.03 +/- 0.38 to 0.52 +/- 0.48, 54 +/- 36%) were greater than that in Group 2c (1.01 +/- 0.46 to 0.64 +/- 0.52, 38 +/- 47%).(ABSTRACT TRUNCATED AT 250 WORDS)