Myocardial infarction is the most common cause of high mortality in the modern world. The short-term survival rate of ST-elevated myocardial infarction (STEMI) has been dramatically increased in the past decades thanks to primary coronary intervention and standardization of treatment. However, the long-term prognosis of patients with acute myocardial infarction (AMI) is still poor, especially in the aging population, due to heart failure related to inappropriate myocardial fibrosis and subsequent left ventricular (LV) remodeling. Despite the amelioration of STEMI management, LV remodeling still occurs in approximately 1/3 of all STEMI patients. Therefore, early identification of such patients may help the optimization of therapy and eventually the outcomes.

One characteristic of activated cardiac fibroblasts is the expression of FAP (fibroblast activation protein). A tracer (FAP inhibitor) for positron emission tomography that targets FAP has been used to measure relative FAP density indicative of activated fibroblasts in different cancer entities. However, whether it can reliably assess myocardial fibrosis and predict the poor prognosis caused by LV remodeling is not yet known. Therefore, We aim to observe active myocardial fibrosis process in patients with AMI, and analyze its relationship with the patients'prognosis in a longitudinal study through 68Ga-FAPI PET/MRI.

Inclusion Criteria:

• between 18-75 years old
• diagnosed with coronary angiography
• performed percutaneous coronary intervention，with successful myocardial reperfusion

Exclusion Criteria:

• unstable hemodynamics
• MR contraindications (such as pacemaker or nerve stimulator or metal foreign body, high fever, severe renal failure, etc.)
• Claustrophobia