Objectives: This study was designed to evaluate dobutamine stress echocardiography in identifying reversible dysfunction and assessing the extent of irreversibly damaged myocardium early in acute myocardial infarction.
Background: Several experimental and clinical studies have suggested that dobutamine enhances contractile function of stunned or hibernating, or both, myocardium. It is important for clinical strategy to predict the magnitude of improvement in myocardial function early in acute myocardial infarction.
Methods: We studied 21 patients with a reperfused first anterior myocardial infarction. Two-dimensional echocardiography was performed before and during dobutamine infusion (10 micrograms/kg body weight per min) at a mean of 3 days after the infarction. Follow-up echocardiography was performed at a mean of 25 days later. To assess segmental wall motion, we divided the left ventricle into 17 segments and assigned a wall motion abnormality score: 3 = dyskinesia or akinesia; 0 = normal. Improvement in wall motion was indicated by a decrease of at least one grade in segmental score. For quantitative assessment, the ratio of endocardial length showing dyskinesia or akinesia to a left ventricular endocardial length (akinetic length ratio) was determined in the apical long-axis view at each stage.
Results: Sensitivity and specificity of dobutamine infusion in detecting improvement in wall motion at follow-up echocardiography were 83% (55 of 66 segments) and 86% (43 of 50 segments), respectively. Excellent correlation was found (r = 0.93, p < 0.001; absolute difference [mean +/- SD] 0.03 +/- 0.05) between the akinetic length ratios measured during dobutamine infusion and in the late convalescent stage.
Conclusions: In the early stage of acute myocardial infarction, low dose dobutamine stress echocardiography provides a useful method for predicting reversible dysfunction with excellent sensitivity and specificity and can also be used to quantitate the extent of irreversibly damaged myocardium.