The primary objective of the trial is to compare the efficacy of early with deferred invasive strategy for patients with ST-segment elevation myocardial infarction (STEMI) within 24-48h of symptom onset.

At present, timely primary percutaneous coronary intervention (PCI) is the preferred strategy for 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.

To our knowledge, due to the long onset time and insufficient antiplatelet/anticoagulant treatment, infarct-related artery in STEMI patients beyond 24h of symptom onset frequently suffer from severer thrombus burden. In this situation, the risk of no-reflow in primary PCI is high. Meanwhile, myocardial coagulative necrosis would be fully developed during 24-72h from symptom onset, the risk of perioperative cardiac rupture may also rise. These bring some doubts about the benefits of early invasive strategy for 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 compare early with deferred invasive strategy for the subgroup of STEMI patients, investigators plan to perform a controlled, randomized trial to compare the efficacy of early with deferred 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: ≥2 mm ST-segment elevation in 2 contiguous precordial leads or ≥1 mm ST-segment elevation in 2 contiguous extremity leads;
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. Congenital heart disease or severe valvular disease;
7. eGFR <30 ml/min/1.73 m2;
8. History of malignant tumors;
9. Combined with other diseases and life expectancy ≤12 months;
10. Pregnancy;
11. Inclusion in another clinical trial;
12. Inability to provide informed consent or not available for follow-up judged by investigator.