What is the initial management for a patient presenting with ST-Elevation Myocardial Infarction (STEMI)?

STEMI Initial Management

Immediate primary percutaneous coronary intervention (PCI) within 120 minutes of diagnosis is the preferred reperfusion strategy and should be pursued aggressively, with fibrinolytic therapy reserved only when timely PCI is not achievable. 1, 2

Immediate Actions at First Medical Contact

• Obtain and interpret 12-lead ECG within 10 minutes of first medical contact to confirm STEMI diagnosis 2
• Initiate continuous ECG monitoring with defibrillator capacity immediately 2
• Administer aspirin 150-325 mg orally (or 250-500 mg IV if unable to swallow) as soon as possible 1, 2
• Do NOT routinely administer oxygen unless oxygen saturation is <90% 2

Reperfusion Strategy Selection

Primary PCI (Preferred Strategy)

Primary PCI is indicated when it can be performed within 120 minutes of STEMI diagnosis by an experienced team. 1, 2

Key implementation steps:

• Transfer patient directly to catheterization laboratory, bypassing the emergency department 2
• Administer a potent P2Y12 inhibitor before or at the time of PCI: prasugrel 60 mg loading dose (then 10 mg daily) or ticagrelor 180 mg loading dose, or clopidogrel 600 mg if these are unavailable or contraindicated 1, 2, 3
• Give unfractionated heparin 100 U/kg IV bolus during PCI (60 U/kg if using GP IIb/IIIa inhibitors) 2
• Fondaparinux must NOT be used for primary PCI 1, 2

Critical caveat for prasugrel: Do not use in patients ≥75 years old (increased fatal bleeding risk), <60 kg body weight (consider 5 mg maintenance dose instead), or with prior stroke/TIA (contraindicated) 3

Fibrinolytic Therapy (When PCI Cannot Be Performed Within 120 Minutes)

Initiate fibrinolytic therapy as soon as possible, preferably in the pre-hospital setting, if anticipated time to PCI exceeds 120 minutes. 1, 2, 4

Fibrinolytic protocol:

• Administer a fibrin-specific agent: tenecteplase (preferred, single weight-adjusted bolus: 30 mg if <60 kg, 35 mg if 60-69 kg, 40 mg if 70-79 kg, 45 mg if 80-89 kg, 50 mg if ≥90 kg), alteplase, or reteplase 1, 4
• For patients ≥75 years old, reduce tenecteplase dose by 50% to minimize stroke risk 2, 4
• Continue aspirin (oral or IV) 1, 4
• Add clopidogrel 300-600 mg loading dose 1, 4
• Initiate anticoagulation with enoxaparin (IV bolus followed by subcutaneous, preferred over unfractionated heparin) or weight-adjusted unfractionated heparin IV bolus followed by infusion, continuing until revascularization or up to 8 days of hospitalization 1, 4

Post-fibrinolysis management:

• Transfer ALL patients to PCI-capable center immediately after fibrinolysis 1, 4
• Perform rescue PCI immediately if fibrinolysis fails (<50% ST-segment resolution at 60-90 minutes) or if hemodynamic/electrical instability develops 1, 4
• Perform angiography and PCI of infarct-related artery 2-24 hours after successful fibrinolysis 1, 4

Special Circumstances

Cardiogenic Shock

• Emergency angiography and PCI (or CABG) are mandatory regardless of time delay from MI onset 1, 2
• Intra-aortic balloon pump counterpulsation should be performed if patient does not stabilize quickly with pharmacological therapy 1

Cardiac Arrest with STEMI

• Initiate therapeutic hypothermia immediately in comatose patients 1
• Proceed directly to angiography and PCI 1, 2

In-Hospital Management

• Perform echocardiography during hospitalization to assess LV/RV function, detect mechanical complications, and exclude LV thrombus 1, 2
• Initiate high-intensity statin therapy immediately 1, 2
• Start ACE inhibitor within 24 hours in patients with heart failure, LV dysfunction (LVEF <40%), diabetes, or anterior infarct 1, 2
• Initiate oral beta-blocker in patients with heart failure or LVEF <40% (avoid IV beta-blockers in hypotension, acute heart failure, or AV block) 1, 2

Maintenance Antithrombotic Therapy

• Continue dual antiplatelet therapy (aspirin 75-100 mg plus P2Y12 inhibitor) for 12 months unless excessive bleeding risk 1, 2
• Add proton pump inhibitor in patients at high gastrointestinal bleeding risk 1, 2
• Target LDL-C <1.8 mmol/L (70 mg/dL) or ≥50% reduction if baseline 1.8-3.5 mmol/L 1, 2

Critical Pitfalls to Avoid

• Do NOT delay reperfusion to obtain detailed history or perform non-essential testing 2
• Do NOT perform PCI on non-infarct arteries during primary PCI in hemodynamically stable patients 1
• Do NOT use fondaparinux as sole anticoagulant for primary PCI 1, 2
• Do NOT give IV beta-blockers in acute phase if hypotension, heart failure, or bradycardia present 1
• Do NOT use prasugrel in patients with prior stroke/TIA (contraindicated) or age ≥75 years (generally not recommended) 3
• Atypical presentations (especially in women, elderly, diabetic patients) may delay diagnosis—maintain high index of suspicion 2