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

Immediate Treatment for ST-Elevation Myocardial Infarction (STEMI)

Primary percutaneous coronary intervention (PCI) performed within 90-120 minutes of first medical contact is the definitive treatment for STEMI, and all immediate actions should be directed toward achieving this goal. 1, 2

Initial Actions (Within 10 Minutes)

• Obtain 12-lead ECG immediately at first medical contact with a maximum target delay of 10 minutes to confirm ST-segment elevation >0.1 mV in at least two contiguous leads, new left bundle branch block, or true posterior MI 1, 2
• Administer aspirin 150-325 mg (oral or IV if unable to swallow) immediately unless absolute contraindication exists 1, 2
• Initiate continuous cardiac monitoring with defibrillator capacity immediately available 1, 2
• Establish IV access and provide oxygen only if saturation <90% (routine oxygen is not recommended for patients with saturation ≥90%) 1, 2
• Administer morphine 4-8 mg IV for pain control if needed 2, 3

Antiplatelet and Anticoagulation Therapy

• Load with a potent P2Y12 inhibitor before or at the time of PCI: prasugrel 60 mg or ticagrelor (or clopidogrel if these are unavailable or contraindicated) 1, 2, 4
• Administer unfractionated heparin as weight-adjusted IV bolus (100 U/kg, or 60 U/kg if GPIIb/IIIa inhibitors used) 1, 2
• Do not delay antiplatelet therapy while waiting for laboratory results or coronary anatomy 2, 3

Reperfusion Strategy Decision

Primary PCI Pathway (Preferred)

• Transfer directly to catheterization laboratory bypassing emergency department if PCI can be performed within 90-120 minutes of first medical contact 1, 2
• PCI-capable centers must provide 24/7 service and perform primary PCI without delay 1, 2
• Use radial access and drug-eluting stents as standard of care 2
• Avoid fondaparinux for primary PCI (it is contraindicated in this setting) 1, 2, 3

Fibrinolytic Pathway (When PCI Unavailable)

If primary PCI cannot be performed within 120 minutes, initiate fibrinolytic therapy within 30 minutes of STEMI diagnosis, preferably in the pre-hospital setting. 1, 2

• Administer a fibrin-specific agent: tenecteplase (preferred), alteplase, or reteplase 1, 2
• Add clopidogrel to aspirin 1, 2
• Provide anticoagulation with enoxaparin IV followed by subcutaneous (preferred over unfractionated heparin) or weight-adjusted unfractionated heparin until revascularization or for duration of hospital stay (up to 8 days) 1, 2
• Transfer immediately to PCI-capable center after fibrinolysis for angiography within 3-24 hours 1, 2
• Perform rescue PCI immediately if fibrinolysis fails (<50% ST-segment resolution at 60-90 minutes) or if hemodynamic/electrical instability develops 1, 2

Time-Specific Considerations

• For patients presenting <2 hours from symptom onset: immediate fibrinolysis may be considered if expected delay to PCI exceeds 60 minutes 1
• For patients presenting 2-3 hours from symptom onset: either immediate fibrinolysis or PCI with possible delay of 60-120 minutes is reasonable 1
• For patients presenting 3-12 hours from symptom onset: PCI with possible delay up to 120 minutes is preferred over initial fibrinolysis 1
• For patients presenting >12 hours from symptom onset: reperfusion therapy is indicated only if ongoing ischemia or hemodynamic instability present 1

Special Populations Requiring Immediate PCI

• Cardiogenic shock: immediate transfer to PCI-capable facility regardless of time from symptom onset (within 18 hours of shock onset if <75 years old) 1, 2
• Severe heart failure: consider immediate invasive strategy 1
• Contraindications to fibrinolysis: immediate transfer to PCI-capable facility (door-to-departure time <30 minutes) 1
• Cardiac arrest with ST-elevation on post-resuscitation ECG: emergency coronary angiography 1, 2

Critical Pitfalls to Avoid

• Never administer IV beta-blockers acutely in STEMI patients as they may worsen hemodynamics and are contraindicated 3
• Do not combine fibrinolytic therapy with immediate PCI (facilitated PCI is harmful) 1
• Avoid NSAIDs for pain relief due to increased risks of mortality, reinfarction, hypertension, heart failure, and myocardial rupture 1, 3
• Do not delay reperfusion while waiting for cardiac biomarkers - treat based on clinical presentation and ECG 3
• Do not administer routine pre-treatment with fibrinolytics before PCI in patients being transferred for primary PCI 1

Post-Reperfusion Immediate Management

• Continue cardiac monitoring for at least 48 hours 3
• Initiate dual antiplatelet therapy (DAPT) for 12 months with aspirin 75-100 mg plus prasugrel or ticagrelor 1, 2
• Start oral beta-blocker within 24 hours after successful reperfusion if no contraindications (heart failure, LVEF <40%) 1, 2, 3
• Initiate ACE inhibitor within 24 hours if heart failure, LV systolic dysfunction, diabetes, or anterior infarct present 2
• Begin high-intensity statin therapy as early as possible 2