Background: The key of acute ST-segment elevation myocardial infarction (STEMI) treatment is to restore myocardial perfusion as soon as possible. Direct percutaneous coronary intervention (PCI), as the most effective means of treatment, it can open up the infarct-related artery (IRA) as early as possible. However, in some cases, myocardial reperfusion cannot restore the myocardium to the optimal level, which is known as the ‘no-reflow’ phenomenon. Acute MI involves electrochemical and metabolic alterations of cardiac muscles, these changes have a complex effect on the duration of action potentials in the ischemic zone and ischemic border zone; thus, TPE and QT intervals display modestly compatible changes.Patients and methods: This cross sectional study was conducted on 100 patients with acute STEMI managed by PPCI who admitted Cardiology Department, Zagazig University Hospitals.All patients underwent medical history taking, clinical examination and ECG were done to all patients before procedure and after primary PCI to assess changes. Results: The incidence of Post procedure no reflow detect by TIMI flow<3 grade was 30.0%,significant longer post cQTand post cTPE duration in no reflow groupI,LAD as infarct related artery was significant and higher in noreflow group I,multivariate regression predictors of noreflow post PCI were post cTPE ≥112.5, diabetes mellitus, hypertension and smoking. Conclusion: The present study demonstrated that prolonged TPE interval is associated with reperfusion features in patients with STEMI, and that a prolonged post cTPE≥112.5 could be used as a marker for no reflow . It also should be noted that the presence of more frequent history of diabetes , hypertension and smoking were significant predictors of no reflow .