The First-In-Man Use of Coronary Sinus Balloon Pump in STEMI Patients Treated by Primary PCI

Inclusion Criteria: Clinical inclusion criteria： 1. Subjects aged ≥18 and ≤80 years with clinically confirmed ST-segment elevation myocardial infarction (STEMI). 2. Left Ventricular Dysfunction: Left ventricular ejection fraction (LVEF) ≤50% assessed by pre-PCI echocardiography or left ventriculography. 3. Ischemic Symptoms: Presence of myocardial infarction symptoms consistent with ischemic timing (e.g., persistent chest pain, with or without dyspnea, nausea/vomiting, diaphoresis, syncope), with symptom onset between 6 and 24 hours prior to enrollment. 4. Electrocardiographic Evidence: * Acute anterior wall myocardial infarction confirmed by 12-lead ECG, demonstrating ST-segment elevation ≥1 mm (0.1 mV) in ≥2 contiguous precordial leads. * For leads V2 or V3: Men: ST-segment elevation ≥2 mm (0.2 mV) Women: ST-segment elevation ≥1.5 mm (0.15 mV). 5. PCI Eligibility: Candidate for primary percutaneous coronary intervention (PCI). 6. Subjects who can understand the purpose of the trial, voluntarily participate and acknowledge the risks and benefits described in the informed consent document by signing the informed consent form, and can conscientiously complete clinical follow-up as required Angiography Inclusion Criteria: 1. Target Lesion Location: Located in the proximal or mid segment of the Left Anterior Descending artery (LAD). 2. Pre-PCI TIMI Flow: TIMI flow grade 0 or 1 in the target vessel prior to percutaneous coronary intervention (PCI). Exclusion Criteria: 1. Presence of implants or foreign bodies within the coronary sinus. 2. Target lesion involving the left main coronary artery or ≥50% stenosis in the left main coronary artery. 3. Known hypersensitivity to medications or devices required during PCI or the investigational device (including but not limited to: rapamycin, polyurethane in dual antiplatelet therapy, PET, or stainless steel). 4. Pericardial effusion (moderate or larger volume), cardiac tamponade, hemodynamically significant left/right shunts, or severe valvular heart disease. 5. Intracardiac thrombus detected by echocardiography within 30 days prior to enrollment. 6. History of acute myocardial infarction (AMI) or documented hospitalization for Q-wave infarction. 7. History of cerebral infarction, intracranial hemorrhage, transient ischemic attack (TIA), or reversible ischemic neurologic deficit within the past 6 months, or permanent neurological deficits. 8. Hemoglobin \<90 g/L, platelet count \<80×10⁹/L, history of bleeding disorders/coagulopathy, or refusal to accept blood transfusion. 9. Requiring circulatory support or assisted ventilation therapy. 10. Cardiac arrest or cardiopulmonary resuscitation (CPR) \>5 minutes during pre-procedural baseline or intra-procedural period. 11. Unsuitable femoral or jugular venous access. 12. Contraindications to cardiac magnetic resonance imaging (CMR), including claustrophobia, CMR-incompatible implants/foreign bodies, or gadolinium contrast allergy/intolerance. 13. Prior coronary artery bypass grafting (CABG). 14. Visible collateral circulation formation distal to the target lesion in the target vessel. 15. Current participation in another investigational drug/device trial (prior to primary endpoint completion) or planned enrollment in another trial within 12 months post-procedure. 16. Severe renal dysfunction (eGFR \<30 mL/min/1.73m² by MDRD equation\*) or ongoing hemodialysis. 17. Active malignancy treatment within the past 12 months. 18. Chronic obstructive pulmonary disease (COPD) requiring home oxygen therapy or chronic steroid therapy. 19. Impaired consciousness during PCI, cardiogenic shock (persistent SBP ≤90 mmHg despite conservative therapy), or pulmonary edema (peripheral SpO₂ \<90% with rales). 20. Any vascular PCI performed within 7 days prior to hospitalization. 21. Fibrinolytic therapy administered within 24 hours prior to hospitalization. 22. Non-target lesions requiring treatment during index PCI or within 1 week post-procedure (excluding LAD and its branches). 23. Pregnancy, lactation, or female subjects planning pregnancy within 1 year post-procedure unable to complete follow-up. 24. Poor protocol compliance per investigator's judgment, or subjects deemed ineligible due to other reasons.