This is a prospective, multicenter, open-label, randomized, controlled, parallel group study, in which ST-segment Elevation Myocardial Infarction (STEMI) patients with high thrombus burden(TIMI thrombus grade ≥3) are included. Patients are randomized to be treated with or without manual thrombus aspiration(TA) during primary percutaneous coronary intervention(PPCI) by a ratio of 1:1.

This study is intended to explore the efficacy of thrombus aspiration (TA) in ST-Segment Elevation Myocardial Infarction (STEMI) patients with high thrombus burden who received primary PCI within 12 hours after the onset of symptoms, reducing the incidence of cardiovascular death, recurrent myocardial infarction, stent thrombosis, target vessel revascularization within 180 days or stroke in 30 days.

Inclusion Criteria:

1. Age ≥ 18 years;
2. STEMI patients undergoing primary PCI within 12 hours after the onset of symptoms;
3. High thrombus burden after guidewire passes the lesion (TIMI thrombus grade ≥3);
4. Informed consent must be voluntary;

Exclusion Criteria:

1. Haemodynamic instability or cardiogenic shock;
2. After thrombolytic therapy;
3. The predicted survival time is less than 6 months due to non-cardiac disease;
4. History of coronary artery bypass grafting;
5. Participate in other researches within 30 days;
6. Preoperative gastrointestinal bleeding or contraindications to dual antiplatelet therapy;
7. Patients were considered unsuitable by other researchers.