The goal of this clinical trial is to compare the efficacy and safety of intracoronary rhTNK-tPA or Tirofiban in patients with ST-segment elevation myocardial infarction and high thrombus burden. The main questions it aims to answer are:

• Is the efficacy of intracoronary rhTNK-tPA non-inferior to intracoronary Tirofiban for the treatment of ST-segment elevation myocardial infarction in patients wiht high thrombus burden?
• Does intracoronary rhTNK-tPA increase the incidence of bleeding events?

This multicenter RCT study plans to enroll 300 patients, who are randomly divided into two groups: intracoronary rhTNK-tPA or Tirofiban by 1:1. The primary efficacy endpoint was post-PCI corrected TIMI frame count (CTFC). Major adverse events (death, recurrent myocardial infarction, ischemic stroke, or hospitalization for heart failure) were observed at 1 year follow-up.

Inclusion Criteria:

• Age 18-75 years old;
• STEMI within 12 hours of onset;
• TIMI flow grade 0-2 or TIMI thrombus grade ≥4 after thrombus aspiration or balloon dilation
• Radial artery access

Exclusion Criteria:

• A functional coronary collateral supply (Rentrop grade≥2) to the infarctrelated artery
• Known or suspected old myocardial infarction of target vessels
• Rescue PCI
• Cardiogenic shock
• Contraindications to Tirofiban or rhTNK-tPA
• Severe hepatic and renal insufficiency (alanine aminotransferase ≥5 upper limit of normal; estimated glomerular filtration rate <30ml/min/1.73m2, or on dialysis)
• Prolonged (> 10 minutes) cardiopulmonary resuscitation
• Definite mechanical complications (including ventricular septal perforation, or rupture of the Papillary tendon bundle, or rupture of the left ventricular free wall)
• Severe chronic obstructive pulmonary disease or respiratory failure
• Severe infection
• Neurological disorders
• Malignant tumors or other pathophysiological conditions with an expected survival time of less than 1 year
• Pregnant or lactating women