Background: The aim of this study was to evaluate the relationship between exercise-induced QT dispersion and condition of infarct-related myocardium including myocardial scar after angioplasty assessed with exercise perfusion single photon emission computed tomography(SPECT). Methods: Exercise thallium-201 SPECT was performed 6 months after successful direct angioplasty in 67 male patients(60.6±11.5 years), who had Q wave infarction resulting from single vessel disease, and the number of perfusion defect areas(DS) was measured at rest and exercise together with QT(QTc) dispersion. Results: In 52 patients with resting perfusion defects, the exercise-induced change in DS was correlated to the change in QT(or QTc) dispersion(r=-0.51 or r=-0.531, p< 0.0001). When the patients were grouped according to the patterns of transient perfusion defect, there were significant differences in QT dispersion and QTc dispersion among infarct-related three groups(reverse, fixed, and partial redistributions) and normal volunteers(QT dispersion;-5.7±12.7 ms in 13 patients with reverse redistribution,-16.3±13.1 ms in 30 patients with fixed redistribution,-28.9±29.5 ms in 9 patients with partial redistribution, and +3.4±20.9 ms in 12 normal volunteers, p=0.0098; QTc dispersion; +18.2±20.8 ms, +1.4±16.7 ms,-15.4±30 ms, and +19±27.5 ms, p=0.0017, respectively). QTc dispersion estimated the SPECT image patterns(p=0.0002) with a sensitivity of 67.3%, a specificity of 83.7%and an accuracy of 78.2%. Conclusions: The change with exercise in QT dispersion may help detect the condition of infarct-related myocardium after angioplasty.
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