This study aim to investigate the effect of ivabradine on reducing infarct size and improving left ventricular remodeling after in patients undergoing primary PCI for ST-elevation myocardial infarction through myocardial enhanced MRI.

Investigators will enroll 240 patients with STEMI who were admitted to the Chinese PLA General Hospital between October 2020 and October 2021，the investigators randomly assign eligible patients in a 1:1 ratio to either ivabradine or oral placebo befor primary PCI. The treatment was initiated after primary PCI with ivabradine orally for 6 months. Primary end point of the study was the area of infarct size measured by cardiac magnetic resonance (CMR). Cardiovascular events concluding stroke, repeat revascularization, rehospitalization for acute heart failure, nonfatal myocardial infarction, and all cause death. All adverse clinical events as well as study end points were monitored and adjudicated by the independent event committee.

Inclusion Criteria:

• STEMI patients: 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
• patients were scheduled to undergo diagnostic cardiac angiography or percutaneous coronary interventions

Exclusion Criteria:

• had once treated by ivabradine
• history of myocardial infarction
• mechanical complications
• Unable to perform myocardial MRI
• liver and kidney failure
• malignant tumor
• unconscious