The goal of this clinical trial is to learn if drug Rivaroxaban works to improve slow flow in STEMI patients after PCI in adults. It will also learn about the safety of drug Rivaroxaban. The main questions it aims to answer are:

Does drug Rivaroxaban Reduce the Corrected TIMI Frame Count (cTFC) in 1 Week After PCI ?

Researchers will compare Combination therapy with rivaroxaban (2.5 mg administered twice daily), aspirin (100 mg administered daily), and clopidogrel (75 mg administered daily) to Dual Antiplatelet Therapy to see if drug Combination therapy with rivaroxaban, aspirin works to treat Slow Flow in STEMI Patients After PCI.

Participants will:

Take drug Combination therapy with rivaroxaban (2.5 mg administered twice daily), aspirin (100 mg administered daily), and clopidogrel (75 mg administered daily) or Dual Antiplatelet Therapy every day for 1 months.

Visit the clinic in 7 days、30 days and 365 days for checkups and tests.

The trial is a multicenter, prospective, randomized, open-label, controlled, pilot trial evaluating the efficacy and safety of rivaroxaban for improving slow coronary flow in ST-segment elevation myocardial infarction (STEMI) patients after percutaneous coronary intervention (PCI). Patients with STEMI who have undergone PCI and exhibit slow coronary flow (TIMI flow grade >0，and < 3, ) are eligible for the clinical trial. Slow coronary flow will be quantitatively assessed using the corrected TIMI frame count (cTFC) method.

The study consists of two parallel treatment groups, evaluating the clinical efficacy and safety of 30 days of combination antithrombotic therapy versus standard therapy, followed up to 365 days. The treatment groups are:

Group 1 - Experimental Antithrombotic Therapy Eligible patients will receive a combination of rivaroxaban (2.5 mg orally twice daily) plus dual antiplatelet therapy (DAPT: aspirin 100 mg/day and clopidogrel 75 mg/day) for a total duration of 30 days (treatment period), followed by assessments at 7 days, 30 days, and 365 days (follow-up period).

Group 2 - Standard Antithrombotic Therapy (Control) Eligible patients will receive standard DAPT (aspirin 100 mg/day and clopidogrel 75 mg/day or ticagrelor 90 mg twice daily) for a total duration of 30 days (treatment period), followed by assessments at 7 days, 30 days, and 365 days (follow-up period).

The primary efficacy endpoint is the change in cTFC from baseline to within 1 week after PCI. Key secondary endpoints include the incidence of Major Adverse Cardiovascular Events (MACE) and bleeding events (assessed by BARC criteria) at 7 days, 30 days, and 365 days.

Inclusion Criteria:

• Age ≥ 18 years, regardless of gender;
• Patients with ST-segment elevation myocardial infarction (STEMI) (meeting the diagnostic criteria of the 2019 Chinese "Guidelines for the Diagnosis and Treatment of Acute ST-Segment Elevation Myocardial Infarction");
• Patients undergoing percutaneous coronary intervention (PCI);
• Patients with slow flow after PCI (TIMI flow grade > 0 but < 3);
• Signed informed consent form and willingness to comply with follow-up.

Exclusion Criteria:

• Presence of malignant tumors or diseases with a life expectancy of less than 1 year;
• Coagulation disorders, diagnosed or suspected hematological diseases (excluding mild or moderate anemia);
• Thrombocytopenia (platelet count < 100 × 10⁹/L); history of severe gastrointestinal diseases or peptic ulcers; active bleeding within the past 3 months or major surgery history; history of intracranial hemorrhage or intracranial aneurysm;
• History of cerebral hemorrhage or ischemic stroke within the past 6 months;
• Patients with cardiogenic shock; systemic infections or immune system diseases; confirmed, highly suspected, or unable to rule out aortic dissection; severe uncontrolled hypertension (systolic blood pressure > 180 mmHg and/or diastolic blood pressure > 110 mmHg);
• Current use of rivaroxaban or requiring long-term anticoagulation therapy (e.g., atrial fibrillation);
• Patients with renal insufficiency (eGFR < 15 mL/min/1.73m²) or hepatic insufficiency (Child-Pugh Class B or C);
• Lactating or pregnant women, or women of childbearing potential unable to use effective contraception during the study period;
• Patients with any contraindications or allergies to rivaroxaban, aspirin, clopidogrel, or ticagrelor;
• Participation in other clinical trials within the past 3 months;
• Other conditions deemed unsuitable for participation by the investigator.