200 consecutive patients presenting with STEMI within 12 hours from the onset of symptoms and having a high thrombotic burden at coronary angiography, defined as the presence of a thrombus size ≥ 2 times the diameter of the vessel, according to a visual estimate. The main objective of the study is to evaluate the effectiveness of thrombectomy (either rheolytic or manual aspiration) as an adjunct to primary or rescue angioplasty, in patients with angiographic evidence high thrombotic burden in the culprit artery. Primary end points: (1) rate of complete ST-segment elevation resolution at 60 minutes after the end of the procedure; (2) infarct size as assessed by delayed-enhancement cardiac magnetic resonance imaging (DE-MRI) at 3 months after the index procedure.

Secondary endpoints: post-procedural TIMI flow grade; post-procedural MBG; infarct transmurality at 3 months; MVO at 3 months; 1-year actuarial freedom from MACEs.

Inclusion Criteria:

1. Prolonged, continuous signs and symptoms of ischemia lasting more than 20 min, starting within 12 hours prior to randomization, and ST elevation ≥ 2mm in ≥2 contiguous ECG leads, or new left bundle branch block (LBBB)
2. Presence of high thrombotic burden in the culprit lesion at diagnostic angiography (defined as the presence of a thrombus size ≥ 2 times the diameter of the vessel, according to a visual estimate, or abrupt cut-off occlusion of a coronary artery ≥3 mm in reference vessel diameter)
3. Written informed consent

Exclusion Criteria:

• Low-risk (ST elevation in ≤2 leads) inferior AMI
• Previous infarction in the same area (assessed by ECG)
• PCI in the 2 weeks prior to AMI
• Active internal bleeding
• History of cerebrovascular accident in the previous 2 years or cerebrovascular accident with a significant residual neurological deficit
• Head or spine surgery or trauma in the previous 2 months
• Recent (within six weeks) gastrointestinal (GI) or genitourinary (GU) bleeding of clinical significance
• Administration of oral anticoagulants within seven days unless prothrombin time is <1.2 times control
• Bleeding diathesis or severe uncontrolled arterial hypertension
• Thrombocytopenia (<100 000 cells/mL)
• Recent (within six weeks) major surgery or trauma
• Intracranial neoplasm, arteriovenous malformation, or aneurysm
• Severe renal or liver failure
• Allergy to aspirin
• Contraindication to MRI examination
• Pregnancy and lactation