ECG-guided Immediate Primary PCI for Culprit Vessel to Reduce Door to Device Time

Inclusion Criteria: * Patient must be \> 18 years of age * Patients have typical chest pain for at least 20 minutes and have ECG changes typical for STEMI (ST elevation≥2mm in two continuous precordial leads or ST elevations≥1mm in two limb leads or new left bundle branch block) or ECG changes compatible with true posterior MI * Symptoms ≥ 30 min and ≤12 hours * Patient and treating interventional cardiologist agree for randomization * Patient provides written informed consent * Diagnostic and therapeutic intervention performed through transradial artery approach * Palpable radial artery. Exclusion Criteria: * Concurrent participation in other investigational study * Current platelet count \<100 x 10\^9cells/L or Hgb \<10 g/dL * Absence of radial artery pulsation * Active bleeding or significant increased risk of bleeding, severe hepatic insufficiency, current peptic ulceration, proliferative diabetic retinopathy * Uncontrolled hypertension * Prior CABG surgery * Fibrinolytic therapy for current MI treatment * patient have a life expectancy of \<180days