The primary objective of the trial is to evaluate the efficacy of early invasive strategy for STEMI patients within 24-48h of symptom onset.

At present, timely primary percutaneous coronary intervention (PCI) is the preferred strategy for ST-segment elevation myocardial infarction (STEMI) patients within 24h of symptom onset. In stable STEMI patients presenting 12 to 48 hours from symptom onset, BRAVE-2 Trial (n = 365) showed improved myocardial salvage and 4-year survival in patients treated with primary PCI compared with conservative treatment alone. However, data is scarce about the reperfusion strategy focusing on STEMI patients within 24-48h of symptom onset. Further investigations are warranted to explore the best timing of invasive strategy for STEMI patients within 24-48h of symptom onset.

Given that no randomized clinical trial is designed especially for STEMI patients within 24-48h of symptom onset, and limited data is available to evaluate the efficacy of early invasive strategy for the special subgroup of STEMI patients, investigators plan to perform a controlled, randomized trial to evaluate the efficacy of early invasive strategy for STEMI patients within 24-48h of symptom onset.

Inclusion Criteria:

1. Age: 18 or over and less than 75 years old;
2. ECG: a) ≥2 mm ST-segment elevation in 2 contiguous precordial leads or ≥1 mm ST-segment elevation in 2 contiguous extremity leads; or b) new or presumable new left bundle branch block in the presence of typical symptoms;
3. Patents with STEMI with symptom onset between 24 and 48 hours before randomization;
4. Signed informed consent form prior to trial participation.

Exclusion Criteria:

1. Patents with STEMI with symptom onset <24h or >48h or uncertain time onset.
2. Prior administration of thrombolytic therapy or attempted PCI before randomization;
3. Presence of indications for primary PCI, such as persistent chest pain, cardiogenic shock, life-threatening arrhythmias or cardiac arrest, severe acute heart failure, and mechanical complications;
4. Coagulopathy, active peptic ulcer, history of cerebral or subarachnoid hemorrhage, stroke within 6 months, other contraindications for antiplatelet or anticoagulant therapy;
5. Known intolerance to antiplatelet (e.g. aspirin, clopidogrel, ticagrelor) and anticoagulant therapy (e.g. heparin, bivalirudin);
6. Presence of contraindications for CMR;
7. Congenital heart disease or severe valvular disease;
8. eGFR <30 ml/min/1.73 m2;
9. History of malignant tumors;
10. Combined with other diseases and life expectancy ≤12 months;
11. Pregnancy;
12. Inclusion in another clinical trial;
13. Inability to provide informed consent or not available for follow-up judged by investigator.