This study is designed to evaluate the efficacy and safety of Recombinant Human Brain Natriuretic Peptide (rhBNP) in improving ventricular remodeling and cardiac function after acute anterior myocardial infarction undergoing percutaneous coronary intervention. 100 patients with acute anterior myocardial infarction after primary Percutaneous Coronary Intervention (pPCI) are randomly assigned 1:1 to rhBNP group(n=50) and control group(n=50) with follow-up of 24 weeks. Both groups are treated with standard therapy of AAMI, with the rhBNP group intravenous dripping rhBNP after pPCI for 3 days and the control group treated with placebo at the same time. The primary endpoint is the change in N terminal pro-B-type natriuretic peptide（NT-proBNP ）and cardiac troponin T(cTnT) level.The secondary endpoint is the change in 24-week echocardiographic including left ventricle ejection fraction (LVEF) , left ventricular end-diastolic volume index (LVEDVI) and left ventricular end-systolic volume index (LVESVI), arrhythmia and cardiovascular events (death, cardiac arrest or cardiopulmonary resuscitation, hospitalization due to heart failure or angina pectoris).

Inclusion Criteria:

1. The first acute anterior myocardial infarction ( AMI ) within 12 hours ( or more than 12 hours but the ischemic symptoms continue ).
2. Age 18-75 years old, gender unlimited
3. Patients with acute anterior myocardial infarction undergoing emergency PCI within the effective time window
4. Successful reflow after interventional therapy ( TIMI = 3 ).
5. To understand and sign the informed consent.

Exclusion Criteria：

1. Patients with a history of coronary artery bypass grafting
2. Patients with cardiogenic shock
3. Patients with systolic blood pressure ( SBP ) ≤ 90 mmHg after treatment with vasopressors
4. Patients with mechanical complications ( ventricular septal perforation, mitral chordae rupture )
5. Patients with suspected aortic dissection
6. Patients with severe liver and kidney dysfunction
7. Allergic or intolerant to rhBNP.
8. Patients with chronic renal insufficiency requiring long-term dialysis
9. Patients using diuretics during the screening period
10. Pregnant / lactating women
11. Heart diseases that are not suitable for vasodilators, such as severe valve stenosis, restrictive cardiomyopathy, restrictive pericarditis, etc

People who are about 18 to 75 years old get the first acute anterior myocardial infarction ( AMI ) within 12 hours ( or more than 12 hours but the ischemic symptoms continue ) and undergo emergency PCI within the effective time window,after which the blood reflows ( TIMI = 3 ).