Safety and Feasibility of Transcatheter Injectable Hydrogel in Acute STEMI Reperfusion Injury (REFINE Study)

Inclusion Criteria: 1. Aged 18 to 80 years; 2. Diagnosed with first-onset acute anterior wall ST-segment elevation myocardial infarction (STEMI), requiring primary percutaneous coronary intervention (PCI) and stent implantation; 3. Ischemic symptoms (e.g., chest pain, precordial discomfort) persist for \>30 minutes, and electrocardiographic findings meet the following criteria: ST-segment (J-point) elevation ≥1.0 mm (i.e., amplitude 0.1 mV) in all conventional leads except leads V2 and V3. For leads V2 and V3, the ST-segment elevation criteria are: ≥2.5 mm in males \<40 years old, ≥2.0 mm in males ≥40 years old, and ≥1.5 mm in females of all ages; 4. The time interval from the onset of ischemic symptoms to the first PCI balloon dilation is ≤12 hours; 5. Admission coronary angiography shows that the left anterior descending artery (LAD) has a TIMI flow grade of 0 (complete occlusion), and the TIMI flow grade reaches 3 after stent implantation; 6. Able to understand the purpose of the trial, voluntarily participate in the study, sign the informed consent form personally or via a legal representative, and be willing to complete the follow-up in accordance with the protocol requirements. Exclusion Criteria: 1. Complicated with cardiogenic shock or cardiac arrest; or complicated with acute myocardial infarction mechanical complications requiring surgical or interventional intervention (e.g., ventricular septal perforation, papillary muscle rupture, free wall rupture), or complicated with giant left ventricular aneurysm; 2. Previously diagnosed with hypertrophic cardiomyopathy, hemodynamically significant congenital heart disease, severe valvular heart disease, chronic cor pulmonale, chronic heart failure, or with a history of cardiac tamponade, pericarditis, or myocarditis; 3. History of previous myocardial infarction, coronary intervention (PCI), or coronary artery bypass grafting (CABG); 4. Cerebrovascular accident (CVA) or transient ischemic attack (TIA) within the past 3 months; 5. Heart failure severity at admission reaches Killip classification Grade III or above; 6. Complicated with malignant arrhythmia, complete atrioventricular block, or new-onset complete left bundle branch block (LBBB); 7. Diagnosed or suspected aortic dissection; 8. Diabetes mellitus with severe complications; 9. Complicated with atrial fibrillation and receiving only warfarin treatment, or with a high bleeding risk; 10. Received thrombolytic therapy prior to PCI; 11. Diameter of the infarct-related artery \< 2 mm or abundant coronary collateral circulation in the risk area; 12. Coronary angiography indicates diffuse vascular lesions or severe calcification that may affect the absorption of protein alginate-based hydrogel; 13. Severe complications (e.g., coronary artery rupture, perforation, or stent dislodgement) occurring during PCI; 14. Received coronary bioresorbable stent implantation; 15. Complicated with severe acute infection requiring systemic treatment; 16. Currently diagnosed with malignant tumor or receiving malignant tumor treatment; 17. Severe autoimmune disease requiring therapeutic intervention; 18. History of severe anemia (hemoglobin \< 60 g/L) or thrombocytopenia (platelet count \< 100×10⁹/L); 19. Known renal insufficiency (including estimated creatinine clearance \< 30 ml/min/1.73 m², or receiving treatment for severe renal insufficiency); 20. Alanine aminotransferase (ALT) level exceeding 3 times the upper limit of normal, with the investigator judging clinically significant liver dysfunction; 21. Known allergy to the study product or any radiocontrast agent; 22. Contraindications to cardiovascular magnetic resonance (CMR) examination (e.g., implanted cardiac pacemaker, implantable cardioverter-defibrillator, nerve stimulator, cerebral aneurysm clip, cochlear implant, or claustrophobia); 23. Cognitive dysfunction, dementia, or severe mental illness; 24. Currently participating in other clinical trials and have not yet reached the primary endpoint; 25. Expected survival period \< 1 year due to comorbidities; 26. Pregnant or lactating women, or fertile subjects who do not take effective medical contraceptive measures during the study period; 27. Other factors that the investigator deems may have a significant impact on result judgment or the safety and efficacy of the subjects.