This study was performed to assess the prevalence of spontaneous improvement of regional left ventricular function in patients after acute myocardial infarction, and to evaluate the role of low-dose dobutamine stress echocardiography for its prediction. In 57 patients with a first acute myocardial infarction (thrombolysis, n = 27; Q-wave, n = 49), regional wall motion was evaluated with 2-dimensional echocardiography at rest, during a low-dose dobutamine stress test performed within 1 week after hospital admission, and at 3-month follow-up. Myocardial viability was considered if there was an improvement of > or = 1 grade in dyssynergic segments from rest to low-dose dobutamine infusion; recovery of regional function was defined as an improvement of > or = 1 grade between rest and follow-up echocardiograms. Wall motion score index decreased from rest to low-dose dobutamine echocardiography (1.46 +/- 0.29 to 1.39 +/- 0.30, p < 0.0001), and this change persisted at follow-up study (1.37 +/- 0.30). No differences were found between patients who did and did not undergo thrombolyis, or between those who had Q-wave and non-Q-wave infarction. At baseline echocardiography, 189 of 627 segments were dyssynergic (85 hypokinetic, 104 akinetic). Viability at low-dose dobutamine stress echocardiography was more frequent in hypokinetic than in akinetic segments (30 of 85 vs 12 of 104, odds ratio 4.18, 95% confidence interval [CI] 1.87 to 9.48).(ABSTRACT TRUNCATED AT 250 WORDS)