Investigators will enroll 240 patients with STEMI who were admitted to the Chinese PLA General Hospital between Januay 2017 and August 2017. STEMI was defined as typical chest pain lasting 30 min within the previous 12 h, a clear ST-segment elevation of N0.1 mV in ≥2 contiguous electrocardiographic leads, and elevated blood levels of troponin T. We randomly assign eligible patients in a 1:1 ratio to either 60mg of trimetazidine or oral placebo befor PCI. Trimetazidine group will accept 20mg of trimetazidine for 12 months after PCI and active Comparator will be given placebo for 12 months after PCI.