Prospective Observational Clinical Study：The Impact of Early rhBNP on Myocardial Remodeling and Reperfusion in Patients With ST-segment Elevation Myocardial Infarction After Percutaneous Coronary Intervention

As prospectively observational study，it brings anterior acute myocardial infarct patients from 2018 JAN. to 2019 JAN, whose predefined time between symptom onset and percutaneous is not more than 12 hours. The door-to-balloon time, present to balloon time and first medical contact-to-balloon time will be documented. ECG in FMC and 90min after PCI also will be record. Patients assigned to the rhBNP group will receive intravenous rhBNP before PCI，and the variety of heart rate and blood pressure will be record. Routinely evaluation of corrected TIMI frame counting（CTFC）, TIMI myocardial perfusion frame counting and TIMI myocardial perfusion grade(TMPG).Blood tests including BNP, CK-MB and CRP are measured at admission and6, 12, 24, 48 hours after PCI. Both Cardiovascular magnetic imaging and echocardiography will be applied in Day 30 and 12 months. The composite endpoint is incidence of all-cause mortality, reinfarct, stroke and target vessel revascularization at hospitalization and follow-up. Principally patients are prevented from any drug affecting microcirculation (GPIIb/IIa receptor agonist, vascular dilation drug, etc.), otherwise it is necessary, which should be documented.