What is the recommended immediate management for a patient presenting with acute ST‑segment‑elevation myocardial infarction (STEMI)?

Management of STEMI

Immediate primary percutaneous coronary intervention (PCI) is the definitive reperfusion strategy for STEMI, with the critical decision point being whether PCI can be achieved within 120 minutes of diagnosis—if not, fibrinolytic therapy must be initiated immediately, preferably within 10 minutes. 1

Initial Diagnostic and Monitoring Steps

• Obtain a 12-lead ECG within 10 minutes of first medical contact to confirm ST-segment elevation or new left bundle branch block 1
• Initiate continuous ECG monitoring with defibrillator capacity immediately upon suspicion of STEMI 1
• Recognize STEMI equivalents that require the same urgent approach: bundle branch block, ventricular pacing, hyperacute T-waves, isolated ST-depression in anterior leads, or diffuse ST-depression with ST-elevation in aVR 1

Reperfusion Strategy Selection Algorithm

If Primary PCI Can Be Performed Within 120 Minutes:

• Primary PCI is indicated for all patients with symptoms ≤12 hours duration and persistent ST-segment elevation (Class I, Level A) 1
• Transfer patients directly to the catheterization laboratory, bypassing the emergency department entirely 1
• Target door-to-balloon time ≤90 minutes (≤60 minutes if presenting within 120 minutes of symptom onset or arriving directly at a PCI-capable hospital) 1
• Perform PCI via radial access with drug-eluting stent implantation as standard of care 1

If Primary PCI Cannot Be Performed Within 120 Minutes:

• Initiate fibrinolytic therapy immediately, ideally within 10 minutes of STEMI diagnosis (Class I, Level A) 1
• Administer a fibrin-specific agent: tenecteplase (weight-based dosing: 30-50 mg IV bolus over 5 seconds), alteplase, or reteplase 1, 2
• The greatest benefit occurs within the first 3 hours of symptom onset—every minute of delay increases myocardial necrosis 3, 4

Immediate Pharmacological Management

For All STEMI Patients:

• Aspirin 75-100 mg oral or IV (if unable to swallow) immediately (Class I, Level B) 1
• Avoid routine oxygen unless SaO₂ <90% (Class III, Level B) 1
• Use morphine for pain control and anxiety reduction, particularly when nitrates are contraindicated 4

For Primary PCI Strategy:

• Administer a potent P2Y₁₂ inhibitor: prasugrel or ticagrelor (preferred over clopidogrel) before or at the time of PCI (Class I, Level A) 1
• Give unfractionated heparin as weight-adjusted IV bolus followed by infusion (enoxaparin or bivalirudin are alternatives) 1
• Do NOT use fondaparinux for primary PCI (Class III, Level B) 1

For Fibrinolytic Strategy:

• Clopidogrel (NOT prasugrel or ticagrelor initially) in addition to aspirin (Class I, Level A) 1, 3
• Enoxaparin IV bolus followed by subcutaneous (preferred over unfractionated heparin) (Class I, Level A) 1, 3
• Continue anticoagulation until revascularization or for duration of hospital stay up to 8 days 1

Post-Fibrinolysis Management Protocol

• Transfer ALL patients to a PCI-capable center immediately after fibrinolysis, regardless of apparent success (Class I, Level A) 1, 3
• Perform rescue PCI immediately if <50% ST-segment resolution at 60-90 minutes, or at any time with hemodynamic/electrical instability or worsening ischemia (Class I, Level A) 1
• Conduct routine angiography and PCI of the infarct-related artery between 2-24 hours after successful fibrinolysis (Class I, Level A) 1, 3
• Switch from clopidogrel to prasugrel or ticagrelor at the time of PCI 3
• Emergency angiography is indicated for patients developing heart failure or shock 1

Critical Contraindications and Special Situations

• Nitrates are absolutely contraindicated for at least 48 hours after phosphodiesterase-5 inhibitor use (e.g., tadalafil) due to risk of severe, potentially fatal hypotension—use morphine for pain control instead 4, 5
• In resuscitated cardiac arrest patients with ST-elevation on post-resuscitation ECG, proceed with primary PCI strategy (Class I, Level B) 1
• Do NOT perform routine PCI of occluded infarct-related artery >48 hours after STEMI onset in asymptomatic patients (Class III, Level A) 1, 5

Dual Antiplatelet Therapy Maintenance

• Continue aspirin 75-100 mg daily indefinitely (Class I, Level A) 1
• Maintain dual antiplatelet therapy (aspirin plus ticagrelor or prasugrel, or clopidogrel if others contraindicated) for 12 months unless excessive bleeding risk (Class I, Level A) 1
• Add proton pump inhibitor in patients at high gastrointestinal bleeding risk (Class I, Level B) 1

Post-Reperfusion Monitoring and Assessment

• Monitor patients for at least 24 hours after reperfusion therapy 1
• Perform routine echocardiography during hospital stay to assess LV/RV function, detect mechanical complications, and exclude LV thrombus (Class I, Level B) 1, 3

Common Pitfalls to Avoid

• Never use prasugrel or ticagrelor as the initial P2Y₁₂ inhibitor with fibrinolytic therapy—clopidogrel is specifically indicated in this setting 3, 5
• Never delay transfer to a PCI-capable center after fibrinolysis—all patients require angiography regardless of apparent success 3, 5
• Never miss the 2-24 hour window for routine angiography after successful fibrinolysis 3, 5
• Flush dextrose-containing IV lines with 0.9% sodium chloride before and after tenecteplase administration to prevent precipitation 2