Electrocardiographic changes during dobutamine stress testing in patients with recent myocardial infarction: relation with residual infarct artery stenosis and contractile recovery.

OBJECTIVE The identification of viable but jeopardized myocardium after acute myocardial infarction (AMI) is of great importance for selecting patients who could benefit from a revascularization procedure. The aim of the study was to determine the accuracy of the dobutamine stress electrocardiogram (ECG) 1) for detecting significant stenosis of the infarct-related artery and 2) for predicting the occurrence of contractile recovery. METHODS AND RESULTS Ninety-four patients underwent dobutamine stress ECG and quantitative angiography within the first week after AMI. A follow-up resting echocardiogram was obtained in all patients at 1 month. Significant stenosis of the infarct-related artery was detected in 76 patients and functional recovery occurred in 56 patients. Dobutamine stress induced ST-segment elevation in 44 patients, ST-segment depression in 17 and T-wave normalization in 34. Increase in QT dispersion and dobutamine ST elevation were more sensitive than chest pain and ST-segment depression (79% and 53% vs. 24% and 17%, respectively; p<0.05) for detecting significant infarct-related artery stenosis. Four independent variables were selected for predicting contractile recovery: > or = 20 ms increase in QT dispersion from baseline to low-dose dobutamine (p = 0.00016), dobutamine-induced ST-segment elevation (p = 0.0009), elective angioplasty of the infarct-related artery (p = 0.001) and T-wave normalization (p = 0.005). CONCLUSIONS The analysis of predischarge dobutamine stress ECG is useful for predicting residual stenosis of the infarct-related artery and contractile recovery in the affected area. QT dispersion changes during the test are the most accurate parameter.