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

Initial Management of STEMI

Immediately administer aspirin 162-325 mg (chewed, not swallowed) and activate emergency medical services for rapid transport to a PCI-capable facility, with the goal of achieving reperfusion within 90-120 minutes of first medical contact. 1

Immediate Recognition and Response

Patient-Level Actions

• If chest pain or ischemic symptoms do not improve or worsen within 5 minutes of one nitroglycerin dose, call 9-1-1 immediately rather than taking additional nitroglycerin doses 1
• Patients should chew (not swallow) aspirin 162-325 mg as soon as possible, ideally while EMS is en route 1
• Never transport by private vehicle—ambulance transport is associated with earlier reperfusion therapy and lower mortality, as 1 in 300 patients with chest pain transported privately suffers cardiac arrest en route 1

Pre-Hospital EMS Management

• Obtain 12-lead ECG within 10 minutes of first medical contact to identify ST-segment elevation >0.1 mV in at least two contiguous leads, new left bundle branch block, or true posterior MI 1
• Establish continuous cardiac monitoring with defibrillator capacity immediately 1
• Administer oxygen only if oxygen saturation is <90%—routine oxygen is not recommended 1
• Transport directly to catheterization laboratory, bypassing emergency department, when STEMI is diagnosed pre-hospital 1

Reperfusion Strategy Decision Algorithm

Primary PCI (Preferred Strategy)

Primary PCI is the preferred reperfusion method when it can be performed within 120 minutes of STEMI diagnosis (or 90 minutes for patients <75 years with large anterior infarction presenting within 2 hours of symptom onset) 1

PCI is specifically preferred when: 1

• Skilled PCI facility is accessible (operators performing >75 primary PCI cases/year, team >36 cases/year)
• Cardiogenic shock is present (Killip class III or greater)
• Diagnosis of STEMI is uncertain
• Contraindications to fibrinolysis exist (prior stroke/TIA, increased bleeding risk)

Fibrinolytic Therapy (When PCI Unavailable)

If primary PCI cannot be performed within 120 minutes, initiate fibrinolysis within 30 minutes of first medical contact, preferably in the pre-hospital setting 1

Fibrinolytic agents in order of preference: 1

• Tenecteplase (preferred fibrin-specific agent)
• Alteplase
• Reteplase
• Streptokinase (if others unavailable)

All patients receiving fibrinolysis must be transferred to PCI-capable center immediately after administration for angiography between 2-24 hours post-fibrinolysis 1

Acute Pharmacological Management

Antiplatelet Therapy

For Primary PCI: 1

• Aspirin: 75-100 mg oral or IV (if unable to swallow) immediately
• P2Y12 inhibitor (before or at time of PCI, continued for 12 months):
  • Prasugrel 60 mg loading dose (preferred), then 10 mg daily 1, 2
    • Reduce to 5 mg daily if weight <60 kg 2
    • Contraindicated if prior stroke or TIA 2
  • Ticagrelor (alternative to prasugrel) 1
  • Clopidogrel 600 mg loading dose only if prasugrel/ticagrelor unavailable or contraindicated 1

For Fibrinolytic Therapy: 1

• Aspirin (oral or IV)
• Clopidogrel 300 mg loading dose (prasugrel contraindicated with fibrinolysis)

Anticoagulation

For Primary PCI: 1

• Unfractionated heparin (weight-adjusted bolus and infusion)
• Bivalirudin is an alternative, especially in high bleeding risk patients

For Fibrinolytic Therapy: 1

• Enoxaparin IV followed by subcutaneous (preferred over unfractionated heparin)
• Continue until revascularization or up to 8 days of hospital stay

Glycoprotein IIb/IIIa Inhibitors

• Reserved only for high intracoronary thrombus burden during PCI—upstream administration is not recommended 1

Critical Time Targets

Door-to-balloon time for primary PCI: <90 minutes 1 Door-to-needle time for fibrinolysis: <30 minutes 1 Symptom onset to reperfusion: minimize at all costs 1

Post-Reperfusion Rescue Strategies

Rescue PCI is indicated immediately when: 1

• Fibrinolysis has failed (<50% ST-segment resolution at 60-90 minutes)
• Hemodynamic or electrical instability develops
• Worsening ischemia occurs at any time

Emergency angiography with PCI is indicated for: 1

• Heart failure or cardiogenic shock
• Recurrent ischemia or evidence of reocclusion after initial successful fibrinolysis

Common Pitfalls to Avoid

• Do not delay aspirin administration waiting for confirmation—give immediately with suspected STEMI 1
• Do not use facilitated PCI (full-dose fibrinolysis followed by immediate PCI)—this strategy is harmful 1
• Do not perform routine PCI of occluded infarct-related artery >48 hours after symptom onset in asymptomatic patients 1
• Do not give IV beta-blockers in patients with hypotension, acute heart failure, or AV block 1
• Do not use fondaparinux for primary PCI 1
• Discontinue NSAIDs immediately—associated with increased mortality, reinfarction, heart failure, and myocardial rupture 1