ECG changes during dobutamine stress test and spontaneous recovery of contractility in patients with myocardial infarction

Abstract

Recent reports suggest a relationship between ECG changes and myocardial viability during dobutamine stress echocardiography in patients with myocardial infarction. The aim of the study was to analyze the predictive value of T-wave normalization and ST segment elevation during low- (10 mucg/Kg/m') and high-dose (40 mucg/Kg/m') dobutamine stress test for late spontaneous recovery of function in patients with a first uncomplicated Q-wave myocardial infarction.

Methods: Seventy eight consecutive patients (59 +/- 9 yrs; males = 67; anterior MI = 41, inferoposterior MI = 37 pts) underwent baseline 2D echo and dobutamine stress test at 9 +/- 2 days from onset of symptoms and they were free of cardiac events during the first three months after myocardial infarction. T-wave normalization (negative T-wave becoming > or = 1 mm upright in > or = 2 leads) and ST segment elevation (> or = 0.1 mm in > or = 2 leads) at low- and high-dose dobutamine infusion were compared with an improvement of contractility in the infarct area detected echocardiographically at three months. A wall motion score decrease in infarct area > or = 2 was the criterion for recovery of contractility.

Results: ST segment elevation occurred in 19/78 patients at low dose (24%) and in 45/78 patients at high dose (58%). Late recovery of contractility in the infarct area was observed in 38/78 patients (49%). The positive and negative predictive values of ST segment elevation for late recovery of contractility were, respectively, 63-56% at low dose and 47-48% at high dose. A baseline negative T-wave in > or = 2 leads was present in 56 patients, and 27 (48%) showed recovery of contractility at three months. T-wave normalization occurred in 14 patients at low-dose (25%) and in 29 patients at high-dose dobutamine infusion (52%). The positive and negative predictive values of T-wave normalization were, respectively, 71-59% at low dose and 62-67% at high dose. Both ECG markers were present in 10/56 patients at low dose and in 19 patients at high dose. The positive and negative predictive values, respectively, were 70-57% at low dose and 58-57% at high dose. At univariate analysis, neither the ECG changes alone nor their combination during dobutamine stress testing were shown to be significant predictors of recovery of function.

Conclusions: Our study demonstrates that in patients with a first uncomplicated Q-wave myocardial infarction, the T-wave normalization and/or the ST segment elevation occurring during early dobutamine stress testing are not reliable predictors of late spontaneous recovery of contractility in the infarct area.