Significance or Dobutamine-induced ST-segment elevation and T-wave pseudonormalization in patients with Q-wave myocardial infarction: Simultaneous evaluation by Dobutamine stress echocardiography and thallium-201 SPECT

The clinical significance of stress-induced ST-segment elevation and T-wave pseudonormalization in infarct-related leads is still controversial, There fore, wc conducted the present study to assess this issue using simultaneou s dobutamine stress echocardiography (DSE) and thallium-201 single-photon e mission computed tomography. A total of 119 patients with Q-wave myocardial infarction were enrolled in this study. There were 58 patients with (group I) and 61 patients without (group II) dobutamine-induced ST-T changes. Lef t ventricular ejection fraction was 43 +/- 13% in group I and 49 +/- 14% in group II (p <0.05). The baseline, low-, and peak-dose global wall motion s cores were similar between these 2 groups (26.2 +/- 6.1 vs 26.2 +/- 6.3 [p = NS]; 24.1 +/- 5.3 vs 23.5 +/- 5.7 [p = NS]; 26.4 +/- 5.7 vs 26.7 +/- 6.1 [p = NS]). The sensitivity, specificity, and accuracy of these ST-T changes for detecting residual myocardial viability and ischemia documented by DSE in all patients were 50%, 53%, and 51% (for viability), and 47%, 48%, and 47% (for ischemia), respectively. The sensitivity, specificity, and accurac y of these ST-T changes for detecting a reversible perfusion defect documen ted by thallium-201 single-photon emission computed tomography were 51%, 54 %, and 52%, respectively. In conclusion, dobutamine-induced ST elevation an d/or T-wave pseudonormalization is associated with poor resting left ventri cular function. These ST-T changes are not associated with residual myocard ial ischemia and viability in the infarct area. Therefore, these electrocar diographic changes alone cannot be reliably considered as distinctive marke rs in formulating the therapeutic strategy of coronary intervention. (C) 19 99 by Excerpta Medica, Inc.