The study tests whether adding supersaturated oxygen (SSO₂) therapy to standard stent treatment can improve heart recovery after a major heart attack (anterior STEMI). Adults treated within 6 hours of symptoms will be randomly assigned to receive either standard care or standard care plus SSO₂. The goal is to see if SSO₂ reduces damage to small heart vessels. Heart function will be checked immediately, after one hour, and again at six months. Follow-up visits will track recovery for up to a year.

This is an investigator-initiated, post-market clinical investigation, interventional, prospective, randomized, controlled, open-label, monocenter study, in subjects with anterior STEMI with two parallel arms comparing the efficacy of SSO2 with standard PCI and standard PCI alone on reduction of microvascular resistances (Rµ)

Patients will be ≥ 18 years old and diagnosed with a first anterior STEMI requiring stent placement, symptoms duration of ≤ 6 hours and culprit lesion in the left anterior descending (LAD) artery with a TIMI (Thrombolysis In Myocardial Infarction) flow 0 or 1 without collateral circulation.

Patients who provide informed consent will be treated with primary PCI with stenting. Once the coronary blood flow is re-established, and after general and angiographic inclusion and exclusion criteria are confirmed, patients will be randomized and enrolled in the study.

A total number of 20 patients will be randomized (1:1) to SSO2 plus PCI arm or standard PCI control arm. Once randomized, SSO2 arm patients will receive SSO2 therapy inside the catheterization laboratory, meanwhile patients randomized in the standard arm will not receive further treatment beyond standard of care.

For both arms, coronary invasive measurements will be performed immediately and 60 minutes after coronary blood flow restoration and then at 6 months timepoint. Baseline clinical and procedural variables will be collected. There will be a clinical follow-up at 30 days ± 7 days, 6 months ± 1 month and 1 year ± 1 month after index event.

Inclusion Criteria:

1. The subject must be ≥ 18 years of age
2. Anterior STEMI (ECG with persistent elevation ≥ 2 mm (0.2 mV) in 2 or more contiguous anterior precordial leads (V2, V3, V4) in men or ≥ 1.5 mm (0.15 mV) in women.
3. Symptoms consistent with myocardial ischemia (persistent chest pain, dyspnea, nauseas/vomiting, fatigue, palpitations or syncope) present for ≤ 6 hours.
4. Provision of informed consent by patient
5. Culprit lesion in proximal or mid LAD.
6. Pre-PCI TIMI flow 0-1.
7. The patient is eligible for primary PCI.
8. Successful PCI of a proximal or mid LAD lesion with commercially available coronary stents and achievement of TIMI 2 or 3 flow
9. Expected ability to place the catheter in the left main coronary ostium to deliver SSO2 therapy with stable and coaxial alignment.

Exclusion Criteria:

1. Previous MI, PCI or CABG occurred before index procedure.
2. Previous history of stroke, transient ischemic attack (TIA) or reversible ischemic neurological deficit within last 6 months.
3. Known severe kidney disease (eGFR <=30 mL/min/1.73) and/or hemodialysis.
4. Known coagulopathy.
5. Known ongoing anticoagulant treatment.
6. Known large pericardial effusion or cardiac tamponade.
7. Known allergies to polyurethanes, PET or stainless steel.
8. Unconscious at presentation.
9. Need for circulatory support.
10. Need for invasive mechanical ventilation.
11. Need for temporal intravenous pacemaker.
12. Cardiopulmonary resuscitation (CPR) cardiac arrest ≥ 5 minutes whom baseline neurologic status is not present.
13. Patients confirmed as pregnant.
14. Active participation in another drug or device investigational trial.
15. Known contraindication for adenosine administration (severe asthma, complicated AV block, critical aortic stenosis, severe cardiac arrhythmias, severe valve diseases).
16. Patient not suitable for femoral access.
17. Patients with mechanical complications of STEMI.
18. Known epicardial stenosis on LAD lesion after stent placement that restricts flow with the SSO2 delivery catheter in place.
19. Ipsilateral insertion of a second sheath in a single femoral artery for SuperSaturated Oxygen Therapy is strictly contraindicated
20. Presence of an intra-aortic balloon pump.
21. Presence of a post-intervention non-stented coronary dissection or perforation.
22. Cardiac valvular stenosis or insufficiency, pericardial disease or non-ischemic cardiomyopathy.
23. Cardiogenic shock.
24. Subjects with ventricular pseudoaneurysm, VSD, or severe mitral valve regurgitation (with or without papillary muscle rupture).
25. Hemoglobin < 10 g/dL.
26. Gastrointestinal or genitourinary bleeding within the last two months, or any major surgery (including CABG) within six weeks of procedure.