Safety and Feasibility of Using a Single Transradial Guiding Catheter for Primary PCI

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 trans-radial/ulnar artery approach. * Palpable radial or ulnar artery * Previous experience of the operator with at least 100 cases of radial artery access within the past year Exclusion Criteria: * Concurrent participation in other investigational study * Current platelet count \<100 x 10\^9cells/L or Hgb \<10 g/dL. * Absence of radial or ulnar 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