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

Initial Treatment for ST-Elevation Myocardial Infarction (STEMI)

Primary percutaneous coronary intervention (PCI) is the preferred reperfusion strategy for STEMI when performed by an experienced team within 90 minutes of first medical contact, with immediate aspirin administration and dual antiplatelet therapy. 1

Immediate Actions at First Medical Contact

• Obtain a 12-lead ECG within 10 minutes of first medical contact to confirm STEMI diagnosis 1
• Administer aspirin immediately (oral 150-325 mg or IV 250-500 mg if unable to swallow) as soon as STEMI is suspected 1
• Initiate ECG monitoring with defibrillator capacity in all patients 1
• Do NOT routinely administer oxygen unless oxygen saturation is <90% 1

Reperfusion Strategy Selection

The choice between primary PCI and fibrinolysis depends critically on time to treatment:

Primary PCI (Preferred Strategy)

Primary PCI should be performed when the door-to-balloon (or first medical contact-to-balloon) time can be achieved within 90 minutes 2

• Transport patients directly to the catheterization laboratory, bypassing the emergency department 1
• For patients presenting to non-PCI-capable hospitals, transfer immediately if PCI can be performed within 120 minutes of STEMI diagnosis 2, 1
• Administer a potent P2Y12 inhibitor (prasugrel 60 mg loading dose or ticagrelor, or clopidogrel if unavailable) before or at the time of PCI 1, 3
• Provide anticoagulation with unfractionated heparin as IV bolus at 100 U/kg (60 U/kg if GPIIb/IIIa inhibitors are used) 1

Fibrinolytic Therapy (When PCI Delayed)

Administer fibrinolysis if the expected delay to PCI exceeds 120 minutes (or 90 minutes in patients <75 years with large anterior STEMI and recent symptom onset) 2

• Initiate fibrinolysis within 30 minutes of first medical contact or hospital arrival 2
• Use a fibrin-specific agent (tenecteplase, alteplase, or reteplase) 1
• Administer aspirin and clopidogrel with fibrinolytic therapy 1
• Continue anticoagulation until revascularization or for duration of hospital stay (up to 8 days) 1
• Transfer to PCI-capable center for angiography 3-24 hours after fibrinolysis, even if successful 2

Special Populations Requiring Immediate Transfer

Certain high-risk patients should be transferred immediately to PCI-capable facilities regardless of time delays:

• Cardiogenic shock patients <75 years old should undergo immediate transfer for PCI within 18 hours of shock onset 2
• Patients with contraindications to fibrinolysis require immediate transfer (door-to-departure time <30 minutes) 2
• Patients ≥75 years with cardiogenic shock should be considered for immediate transfer 2
• Patients with severe heart failure should be considered for prompt transfer 2

Critical Time Goals

The medical system must achieve these benchmarks to reduce mortality:

• Prehospital fibrinolysis: 30 minutes from EMS arrival on scene 2
• In-hospital fibrinolysis: 30 minutes door-to-needle time 2
• Primary PCI: 90 minutes from first medical contact to balloon inflation 2
• Total ischemic time should be kept within 120 minutes (ideally 60 minutes) from symptom onset 2

Common Pitfalls and Caveats

• Do NOT use facilitated PCI (full-dose fibrinolysis followed by immediate PCI) as this strategy increases mortality and bleeding without benefit 2
• Do NOT use fondaparinux for primary PCI anticoagulation 1
• Do NOT delay treatment for patients presenting within 12 hours of symptom onset—the benefit of reperfusion diminishes rapidly with time 2
• For patients weighing <60 kg, consider reducing prasugrel maintenance dose to 5 mg daily due to increased bleeding risk 3
• Prasugrel is contraindicated in patients with prior stroke or TIA 3
• Streptokinase should NOT be readministered if given within the previous 5 days 2

Prehospital Considerations

• Prehospital 12-lead ECG programs significantly improve time to treatment and should be expanded 2
• Prehospital fibrinolysis is reasonable in settings with physicians in ambulances or well-organized EMS systems with transmission capability and ongoing quality improvement 2
• Every community should have a written protocol guiding EMS personnel on destination decisions for STEMI patients 2