Dobutamine-Induced ST-Segment Elevation in Patients With Acute Myocardial Infarction and the Role of Myocardial Ischemia, Viability, and Ventricular Dyssynergy

Abstract

We analyzed the relation between dobutamine-induced Q-wave ST-segment elevation and regional contraction during low (5 to 10 μg/kg/min) and high doses (20 to 40 μg/kg/min) of dobutamine in a series of 391 dobutamine echocardiographic tests performed 10 ± 2 days after a first uncomplicated acute myocardial infarction (AMI). ST-segment elevation was defined as ≥1 mm new or additional J-point elevation with a horizontal or upsloping ST segment lasting 80 ms. Wall motion score index at rest was derived using a 16 segment-4 grade score model. Patients with dobutamine-induced ST-segment elevation had a higher wall motion score index at rest (anterior wall AMI: 1.67 ± 0.27 vs 1.43 ± 0.30, p = 0.0001; inferior wall AMI: 1.44 ± 0.27 vs 1.30 ± 0.18, p = 0.0001) and similar incidence and extent of myocardial viability and homozonal ischemia in comparison with those without ST-segment elevation. The sensitivity, specificity, and accuracy of dobutamine-induced ST-segment elevation for detecting residual homozonal ischemia were 51%, 55%, and 54%, respectively, in patients with anterior wall AMI, and 42%, 68%, and 58%, respectively, in patients with inferior wall AMI. In conclusion, dobutamine-induced ST-segment elevation is not associated with higher incidence and extent of viable or jeopardized myocardium but rather to a greater extent of wall motion abnormalities at rest. Thus, this finding does not represent a clinically reliable discriminator for selecting patients for coronary angiography and possible revascularization procedures.To evaluate the relative role of wall motion abnormalities, myocardial ischemia, and viability in patients with dobutamine-induced ST-segment elevation in Q-wave leads, 391 dobutamine echocardiographic tests performed 10 ± 2 days after a first myocardial infarction were analyzed. Patients with dobutamine-induced ST-segment elevation had a higher wall motion score index at rest (anterior infarction: 1.67 ± 0.27 vs 1.43 ± 0.30, p = 0.0001; inferior infarction 1.44 ± 0.27 vs 1.30 ± 0.18, p = 0.0001) and similar incidence of myocardial viability and homozonal ischemia in comparison with those without ST-segment elevation; the sensitivity, specificity, and accuracy of dobutamine-induced ST-segment elevation for detecting homozonal ischemia were 51%, 55%, and 54%, respectively, in patients with anterior infarction, and 42%, 68%, and 58%, respectively, in patients with inferior infarctions.