The incidence of improvement in regional wall motion of segments with severe contractile abnormalities in the first 10 days after a first acute myocardial infarction (AMI) was assessed with serial gated blood pool scans in 95 patients who received standard medical therapy. Regional wall motion was quantitatively assessed as percent chord shortening in 4 segments in the anterior view and 4 segments in the 45 degree left anterior oblique view. Among 237 segments with no more than 15% shortening (severely hypokinetic or akinetic [SH/A] segments), 59 (25%) improved at least 15% at 10 days, 166 (70%) did not change and 12 (5%) deteriorated by at least 15%. Among 91 patients who had SH/A segments, 37 (41%) had improvement in at least 1 SH/A segment (group 1) and 54 had no improvement in SH/A segments (group 2). Group 1 had a higher initial ejection fraction (EF) (50 +/- 12%) than group 2 (45 +/- 13%, p less than 0.05). The changes in percent shortening of SH/A segments were compared with coronary anatomy in 37 patients who underwent coronary angiography. The 17 patients with 1-vessel coronary artery disease (CAD) had significantly improved wall motion (8.2 +/- 13.4%, p less than 0.005), in contrast to the 20 patients with multivessel CAD (1.8 +/- 11.5%, difference not significant). Among patients with 1-vessel CAD, the improvement was greater in patients with right coronary or left circumflex artery disease (12.8 +/- 14.4%) than in those with left anterior descending disease (4.1 +/- 13.4%, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)