SIGNIFICANCE OF ST SEGMENT CHANGES INDUCED BY DOBUTAMINE STRESS TEST AFTER ACUTE MYOCARDIAL-INFARCTION - WHICH ARE RECIPROCAL

In order to determine the significance of predischarge stress-induced ST segment changes after a first non-complicated acute myocardial infarction, a dobutamine stress test was performed in 104 patients. Dobutamine was infused in doses of 5, 10, 15 and 20 μg . kg-1 . min-1 every 5 min with ECG and blood pressure control. It induced a substantial increase in heart rate and systolic blood pressure. The patients were divided into 4 groups: (1) anterior (n = 28); (2) inferior (n = 32); (3) posteroinferior (n = 27) and (4) high lateral plus anterior or anterolateral (n = 17) infarction. They were followed for 2 to 18 months (mean 7.5 ± 5). In basal conditions the ST segment was elevated in 49 patients and depressed in 20. Combined ST elevation and depression was seen in 11. After dobutamine there was ST elevation in 80 patients, depression in 71 and combined elevation and depression in 60. The magnitude of the maximal ST elevation was correlated with the magnitude of the maximal ST depression in each group of patients. There was a good inverse linear correlation between ST segment shifts in inferior vs high lateral leads, and ST depression was considered as a benign mirror image of opposite ST elevation in such leads. In patients with posterior infarction, anterior ST depression was considered as a mirror image of posterior ST elevation. In the remaining cases ST depression was a criterion of positivity. When ECG and clinical (angina) criteria were considered together, 50 patients had a positive test and 54 a negative test. The clinical evolution was significantly worse in the patients with a positive test. Such patients should be followed closely until symptoms appear. © 1991 The European Society of Cardiology.