What is the initial management of a typical adult patient presenting with ST-Elevation Myocardial Infarction (STEMI) without any known allergies or contraindications?

Initial Management of STEMI

Immediate primary percutaneous coronary intervention (PCI) within 90-120 minutes of first medical contact is the definitive reperfusion strategy for STEMI, with aspirin and a potent P2Y12 inhibitor (prasugrel or ticagrelor) administered immediately, unless primary PCI cannot be achieved within 120 minutes—in which case fibrinolytic therapy should be initiated immediately. 1

Immediate Actions at First Medical Contact

Diagnosis and Monitoring

• Obtain and interpret a 12-lead ECG within 10 minutes of first medical contact 1
• Initiate continuous ECG monitoring with defibrillator capacity immediately 1
• Assess for contraindications to reperfusion therapy (prior stroke/TIA for prasugrel, active bleeding, recent surgery) 1, 2

Symptom Relief and Supportive Care

• Administer morphine sulfate for pain control and anxiety reduction (also reduces sympathetic drive and myocardial oxygen demand) 3
• Avoid routine oxygen unless oxygen saturation is <90% 1
• Do not administer nitrates if the patient has taken phosphodiesterase-5 inhibitors (sildenafil, tadalafil) within 24-48 hours due to risk of fatal hypotension 3

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, 4

Immediate Antithrombotic Regimen for Primary PCI:

• Aspirin: 162-325 mg orally (or IV if unable to swallow) immediately 1
• P2Y12 Inhibitor: Administer a potent agent before or at the time of PCI 1:
  • Prasugrel 60 mg loading dose (preferred for STEMI undergoing PCI) 1, 2
  • OR Ticagrelor 180 mg loading dose (alternative potent option) 1
  • OR Clopidogrel 600 mg loading dose (only if prasugrel/ticagrelor unavailable or contraindicated) 1
• Anticoagulation: Unfractionated heparin as weight-adjusted IV bolus (70-100 units/kg) followed by infusion, targeting ACT 250-350 seconds 1

Critical Prasugrel Considerations:

• Contraindicated in patients with prior stroke or TIA 2
• Consider dose reduction to 5 mg daily maintenance in patients <60 kg (increased bleeding risk) 2
• Generally not recommended in patients ≥75 years except in high-risk situations (diabetes, prior MI) 2
• Discontinue at least 7 days before elective CABG if possible 1, 2

PCI Logistics:

• Transfer patients directly to catheterization laboratory, bypassing emergency department and CCU 1
• Perform immediate angiography with PCI of culprit artery 1
• Continue dual antiplatelet therapy (aspirin + P2Y12 inhibitor) for 12 months 1

Fibrinolytic Therapy (When Primary PCI Cannot Be Achieved Within 120 Minutes)

Fibrinolytic therapy is indicated when primary PCI cannot be performed within 120 minutes of STEMI diagnosis in patients presenting within 12 hours of symptom onset with no contraindications 1, 5

Fibrinolytic Protocol:

• Initiate immediately, preferably in pre-hospital setting 1, 5
• Use fibrin-specific agent: tenecteplase, alteplase, or reteplase 1, 5
• Greatest benefit occurs within first 3 hours of symptom onset—every minute of delay increases myocardial necrosis 5, 4

Antithrombotic Regimen for Fibrinolysis:

• Aspirin: Oral or IV immediately 1, 5
• Clopidogrel 300 mg loading dose (NOT prasugrel or ticagrelor—clopidogrel is specifically indicated with fibrinolysis) 1, 5, 6
• Anticoagulation: Enoxaparin IV bolus followed by subcutaneous (preferred over UFH) 1, 5, 6
  • Alternative: Weight-adjusted UFH IV bolus followed by infusion 1, 5
• Continue anticoagulation until revascularization or for hospital stay up to 8 days 1, 6

Post-Fibrinolysis Management:

• Transfer ALL patients to PCI-capable center immediately after fibrinolysis 1, 5, 6
• Perform routine angiography between 2-24 hours after successful fibrinolysis 5, 6
• Switch from clopidogrel to prasugrel or ticagrelor at time of PCI, maintain for 12 months 5, 6
• Rescue PCI immediately if fibrinolysis fails (<50% ST-segment resolution at 60-90 minutes) or with hemodynamic/electrical instability 1, 5, 6

Additional Immediate Therapies

Beta-Blocker Therapy

• Initiate oral beta-blocker within first 24 hours in patients WITHOUT: 1
  • Signs of heart failure
  • Evidence of low output state
  • Increased risk for cardiogenic shock (age >70, SBP <120 mmHg, sinus tachycardia)
  • PR interval >0.24 seconds, second/third-degree heart block
  • Active asthma or reactive airway disease
• IV beta-blocker may be reasonable for hypertensive patients without above contraindications 1

Statin Therapy

• Initiate high-intensity statin therapy immediately (or continue if already prescribed) 1

Medications to AVOID

• NSAIDs and COX-2 inhibitors: discontinue immediately (increased risk of death, reinfarction, heart failure) 1
• Fondaparinux: contraindicated for primary PCI 1, 5
• Routine oxygen: not indicated unless SaO2 <90% 1

Critical Pitfalls to Avoid

• Do not use prasugrel or ticagrelor as initial P2Y12 inhibitor with fibrinolytic therapy—clopidogrel is specifically indicated 5, 6
• Do not delay transfer to PCI-capable center after fibrinolysis—all patients require angiography regardless of apparent success 5, 6
• Do not administer IV beta-blockers to patients with signs of heart failure, low output, or shock risk—this increases mortality 1
• Do not give prasugrel to patients with prior stroke/TIA—this is an absolute contraindication 2
• Do not miss the 2-24 hour window for routine angiography after successful fibrinolysis 5, 6
• Do not continue clopidogrel after PCI is performed—escalate to potent P2Y12 inhibitor 6

Special Circumstances

Cardiogenic Shock

• Emergency revascularization (PCI or CABG) is indicated regardless of time delay from MI onset 1
• Fibrinolytic therapy should be administered if patient unsuitable for PCI/CABG 1
• Intra-aortic balloon pump may be useful if patient does not quickly stabilize with pharmacotherapy 1

Resuscitated Cardiac Arrest

• Primary PCI strategy is indicated in patients with resuscitated cardiac arrest and ECG consistent with STEMI 1
• Initiate targeted temperature management early after resuscitation 1