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

Emergency Management of ST-Elevation Myocardial Infarction (STEMI)

Primary percutaneous coronary intervention (PCI) within 90-120 minutes of first medical contact is the definitive treatment for STEMI, with immediate aspirin and a potent P2Y12 inhibitor (prasugrel or ticagrelor) administered before or at the time of PCI. 1, 2

Immediate Actions at First Medical Contact

Time-critical interventions must begin immediately:

• Obtain and interpret a 12-lead ECG within 10 minutes of first medical contact to confirm STEMI diagnosis 1, 2
• Initiate continuous ECG monitoring with defibrillator capacity immediately upon patient contact 1, 2
• Administer aspirin 150-325 mg orally (chewable) or IV as the first antiplatelet agent 1, 2, 3
• Administer oxygen only if SaO2 <90%—routine oxygen is not recommended 1
• Provide pain relief with opioids (morphine or equivalent) as needed 1

Reperfusion Strategy Selection

The choice between primary PCI and fibrinolytic therapy depends entirely on time to treatment:

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
• Patients must bypass the emergency department and be transferred directly to the catheterization laboratory to minimize door-to-balloon time 1, 2
• Target door-to-balloon time is <90 minutes for patients presenting directly to a PCI-capable center 1
• Target first medical contact-to-balloon time is <120 minutes for patients requiring transfer 1

Fibrinolytic Therapy (When PCI Unavailable)

• Fibrinolytic therapy is indicated when primary PCI cannot be performed within 120 minutes of STEMI diagnosis 1, 2
• Administer fibrin-specific agents (tenecteplase, alteplase, or reteplase) within 12 hours of symptom onset 1, 2
• Target door-to-needle time is <30 minutes for fibrinolytic administration 1
• Pre-hospital fibrinolytic administration by trained paramedics is the most effective way to shorten delay times when PCI is not rapidly accessible 1

Antithrombotic Regimen

Dual antiplatelet therapy plus anticoagulation forms the foundation of pharmacologic management:

Antiplatelet Therapy

• Aspirin 150-325 mg loading dose administered immediately, continued at 75-100 mg daily indefinitely 1, 2, 3
• Prasugrel 60 mg loading dose (preferred P2Y12 inhibitor for primary PCI) given before or at time of PCI, continued at 10 mg daily for 12 months 1, 2
• Ticagrelor 180 mg loading dose (alternative to prasugrel) given before or at time of PCI, continued at 90 mg twice daily for 12 months 1, 2, 3
• Clopidogrel 300-600 mg loading dose only if prasugrel and ticagrelor are unavailable or contraindicated, continued at 75 mg daily 1, 2, 3

Critical contraindications to note: Prasugrel is contraindicated in patients with prior stroke or TIA 2, 4

Anticoagulation

• Unfractionated heparin (UFH) bolus of 60 U/kg (maximum 4000 U) followed by infusion of 12 U/kg/hour (maximum 1000 U/hour) adjusted to maintain aPTT at 1.5-2.0 times control 1
• UFH is indicated for all patients undergoing percutaneous or surgical revascularization 1
• Monitor platelet counts daily in patients receiving UFH to detect heparin-induced thrombocytopenia 1
• Bivalirudin is an alternative anticoagulant that may be used during primary PCI 5

Post-Reperfusion Monitoring and Management

All patients require intensive monitoring for at least 24 hours after reperfusion:

• Monitor ST-segment resolution, cardiac rhythm, and clinical symptoms for 60-180 minutes after reperfusion therapy initiation 1
• Successful reperfusion is suggested by: relief of symptoms, hemodynamic/electrical stability, and ≥50% reduction in ST-segment elevation on follow-up ECG at 60-90 minutes 1
• Continue telemetry monitoring to detect life-threatening arrhythmias, particularly in patients with heart failure, shock, or serious arrhythmias 1, 3

Additional Medical Therapy

Initiate evidence-based secondary prevention immediately:

• High-intensity statin therapy (atorvastatin 80 mg or rosuvastatin 40 mg) started immediately with target LDL-C <70 mg/dL 2, 3, 4
• Beta-blocker therapy initiated orally within 24 hours unless contraindicated by hypotension, acute heart failure, or cardiogenic shock 2, 3
• ACE inhibitor started within 24 hours if heart failure, LV dysfunction (LVEF <40%), diabetes, or anterior infarction present 3

Special Circumstances Requiring Modified Approach

Cardiogenic Shock

• Emergency revascularization (PCI or CABG) is indicated in patients <75 years old with cardiogenic shock developing within 36 hours of STEMI who have severe multivessel or left main disease, performed within 18 hours of shock onset 1
• Selected patients ≥75 years old with good prior functional status may also benefit from emergency revascularization 1

Resuscitated Cardiac Arrest

• Primary PCI strategy is indicated in patients with resuscitated cardiac arrest and ECG consistent with STEMI 1, 2, 3
• Targeted temperature management initiated early after resuscitation in patients who remain unresponsive 1, 5
• Avoid pre-hospital cooling with rapid infusion of large volumes of cold IV fluid immediately after return of spontaneous circulation 1

Failed PCI or Persistent Ischemia

• Emergency CABG is indicated for: failed PCI with persistent pain or hemodynamic instability, persistent/recurrent ischemia refractory to medical therapy in patients unsuitable for repeat PCI, or life-threatening ventricular arrhythmias with ≥50% left main stenosis or triple-vessel disease 1

Mechanical Complications

• Emergency CABG is indicated at the time of surgical repair of post-infarction ventricular septal rupture or mitral valve insufficiency 1

Critical Pitfalls to Avoid

Common errors that worsen outcomes:

• Never delay reperfusion therapy to obtain additional diagnostic tests or consultations—time to reperfusion is the single most critical determinant of mortality and morbidity 1, 2, 3, 4
• Do not perform routine PCI of an occluded infarct-related artery >48 hours after symptom onset in asymptomatic patients 1
• Do not perform emergency CABG in hemodynamically stable patients with persistent angina but small area at risk 1
• Do not withhold aspirin or P2Y12 inhibitors due to concerns about bleeding risk in most circumstances—the mortality benefit of antiplatelet therapy far exceeds bleeding risk in acute STEMI 1, 2, 4
• Avoid IV beta-blockers in patients with hypotension, acute heart failure, or cardiogenic shock 3

Pre-Hospital System Optimization

Regional STEMI networks dramatically improve outcomes:

• Pre-hospital 12-lead ECG with transmission to receiving hospital allows catheterization laboratory activation before patient arrival, reducing door-to-balloon time 1, 6
• Ambulance personnel trained to recognize STEMI, administer aspirin and opioids, and provide advanced life support improve early mortality 1
• Direct transport to PCI-capable centers rather than initial presentation to non-PCI hospitals reduces total ischemic time 1
• Target ambulance arrival time <15 minutes from call, with ECG transmission within 10 minutes and tele-consultation within 5 minutes 1