Eltahlawi Mohammad Abdalla, Sanad Ahmed Mohamed, Ghazal Kamel Hasan, Abdelwahed Ahmed Taha
Zagazig University, Zagazig, Egypt.
Kobri El-Kobba Military Hospital, Cairo, Egypt.
Egypt Heart J. 2021 Jan 7;73(1):5. doi: 10.1186/s43044-020-00126-5.
QT dispersion (QTd) is related to regional variations in myocardial repolarization. Our study aims to assess the value of QTd in prediction of myocardial ischemia and its severity during stress imaging. We enrolled one hundred patients having stable coronary artery disease (CAD) and fulfilling the "Appropriateness criteria for cardiac radionuclide imaging" (MPI). They were divided into group I including patients with MPI-detected ischemia (50 patients) and group II including patients with normal perfusion scan (50 patients). We excluded unstable CAD and all other causes affecting QTd. During isotope scan, ECGs were taken and QTd was calculated at rest and at maximum heart rate.
QTd was significantly higher in the ischemic group both at rest and exercise (P = 0.000). QTd difference, the difference between QTd at rest and stress, was calculated. QTd difference was significantly lower in normal than in ischemic group (P = 0.003). There was a significant positive correlation between QTd difference and defect size (P = 0.04).
QTd increases in ischemia and the QTd difference (between rest and stress) correlates positively with severity of ischemia. QTd and QTd difference could be used to improve the accuracy of stress imaging test.
QT离散度（QTd）与心肌复极的区域差异有关。我们的研究旨在评估QTd在应激成像期间预测心肌缺血及其严重程度的价值。我们纳入了100例患有稳定冠状动脉疾病（CAD）且符合“心脏放射性核素成像适宜性标准”（心肌灌注显像）的患者。他们被分为I组，包括心肌灌注显像检测到缺血的患者（50例）和II组，包括灌注扫描正常的患者（50例）。我们排除了不稳定型CAD和所有其他影响QTd的原因。在同位素扫描期间，采集心电图并计算静息和最大心率时的QTd。
缺血组静息和运动时的QTd均显著更高（P = 0.000）。计算QTd差值，即静息和应激时QTd的差值。正常组的QTd差值显著低于缺血组（P = 0.003）。QTd差值与缺损大小之间存在显著正相关（P = 0.04）。
缺血时QTd升高，且QTd差值（静息和应激之间）与缺血严重程度呈正相关。QTd和QTd差值可用于提高应激成像检查的准确性。
