The main purpose of this study is to compare the myocardial protection effect of intravenous metoprolol combined with remote ischemic conditioning (RIC) and single treatment before reperfusion in Chinese patients with anterior STEMI. This study sought to find possible strategies to further improve myocardial protection in Chinese patients with anterior STEMI.

This study is a prospective, multi-center, randomized controlled study. It is planned to enroll 1200 patients with anterior STEMI. Immediately after the first medical contact, the patients who were determined by the investigator to meet the inclusion/exclusion criteria were randomized through the interactive web response system (IWRS) and received different pre-reperfusion treatments. The four groups were placebo group, metoprolol group, remote ischemic conditioning (RIC) group and metoprolol & RIC group. Subsequently, the investigator conduct diagnosis and treatment according to the patient's specific conditions and check the serum level of myocardial damage markers (i.e. CK and CK-MB) at the time of admission, 12, 24, 36, 48, 60 hours, respectively. If the patient undergoes PCI treatment, additional detection of myocardial damage markers immediately after PCI is also required. All patients were followed for 1 year with an office visit or a telephone call at 1, 3, 6, 9 and 12 months to evaluate the health status and adverse clinical events of patients.

Inclusion Criteria:

1. ages 18 to 80 years;
2. presenting within 12 h of symptoms onset, with anterior STEMI and planned for pPCI; anterior STEMI was defined as the occurrence of >20 min of chest pain and ST-segment elevation (>2 mm) in at least 2 contiguous precordial leads;
3. sign informed consent;

Exclusion Criteria:

1. systolic blood pressure < 110mmHg;
2. cardiogenic shock or with heart failure symptoms, Killip III~IV;
3. allergic history of metoprolol;
4. history of asthma or the need for bronchodilators;
5. PR interval > 240ms, II~III atrioventricular block；
6. heart rate < 60 beats/min;
7. unable to consent;
8. pregnancy and lactation women;
9. life expectancy for diseases (i.e. cancer) < 1 year.