The purpose of this clinical trial is to preliminarily evaluate the safety and feasibility of the transcatheter injectable protein alginate-based hydrogel developed and manufactured by Myomed Technology (Shaoxing) Co., Ltd. in alleviating reperfusion injury in acute STEMI. This is a randomized controlled trial with a blank control group (conventional PCI treatment). A total of 20 patients will be enrolled in a 1:1 ratio into the test group and the control group.

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.