Background 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. Results 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). Conclusion 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.

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Background: The QT dispersion (QTd) can be used as effective reperfusion marker among cases who undergo primary Percutaneous Coronary Intervention (PCI) after having acute myocardial infarction. Objective: Study of the correlation between myocardial perfusion and QT dispersion on 12 lead surface ECG among patients who had acute ST-elevation myocardial infarction (STEMI) managed by primary PCI. Patients and methods: In a prospective cohort study, 100 cases admitted to the Cardiology Departments of Zagazig University Hospital and El-Zaitoun Specialized Hospital within 12 hours of symptom onset were recruited. This study included all patients who fulfilled the criteria for acute STEMI and were candidates for primary PCI. All cases underwent electrocardiogram (ECG), echocardiogram (ECHO), and coronary angiogram. Results: Myocardial electrical heterogeneity was rapidly restored to normal after effective reperfusion, whereas insufficient tissue reperfusion (Myocardial blush grade (MBG) lower or equal to 2) even with Thrombolysis in Myocardial Infarction (TIMI) III flow, was not related to the resolution of the increased QTd. QTd and corrected QTD (QTcd) were significantly shortened following recanalization of the infarct-related artery among cases with successful tissue-level myocardial reperfusion (MBG3). The pre-procedural QTd is a significant predictor of the patients' MBG (i.e., The MBG improves with lower pre-procedural QTd values and worsens with higher QTd values.) Conclusion: Effective revascularization of myocardial tissue was determined by MBG related to normal electrical heterogeneity restoration with reduction of QTd in the jeopardized myocardium. The pre-procedural QTd is a significant predictor of the patients' MBG.