Primary percutaneous coronary intervention (PPCI) is the preferred reperfusion strategy for treating acute ST-segment elevation myocardial infarction (STEMI). The main goals are to restore epicardial infarct-related artery patency and to achieve microvascular reperfusion as early as possible. No-reflow is the term used to describe inadequate myocardial perfusion of a given coronary segment without angiographic evidence of persistent mechanical obstruction of epicardial vessels and it refers to the high resistance of microvascular blood flow encountered during opening of the infarct-related coronary artery.

Despite optimal evidence-based PPCI, myocardial no-reflow can still occur, negating many of the benefits of restoring culprit vessel patency, and is associated with a worse in-hospital and long-term prognosis. Several strategies have been tested to revert the no-reflow including the use of thrombectomy, glycoprotein IIb/IIIa inhibitors and the use of intracoronary adenosine, but none has been demonstrated to effectively counteract the phenomenon.

The trial aims to show the effect of the administration of intracoronary adrenalin on myocardial reperfusion assessed by magnetic resonance in patients with STEMI undergoing PCI and with persistent coronary angiographic The Thrombolysis in Myocardial Infarction (TIMI) 0-1 flow during the interventional procedure after failure of standard therapy.

Inclusion Criteria:

• ≥18 years of age
• presentation within 6-7 h of symptom onset of STEMI
• eligibility for reperfusion by primary-PCI
• TIMI flow grade 0-1 during the interventional procedure in the culprit vessel after the initial opening of the vessel with the coronary wire

Exclusion Criteria:

• evident clinical arrhythmias (ventricular tachycardia/ventricular fibrillation)
• evidence of coronary dissection or spasm
• Parkinson symptoms
• closed angle glaucoma
• thyroid disorders
• known history to hypersensitivity to the drug
• pregnancy
• stage 4 or 5 CKD (eGFR <30 mL/min/1.73 m2)