What is the immediate treatment for a patient presenting with ST elevation myocardial infarction (STEMI)?

Immediate Treatment for ST Elevation Myocardial Infarction (STEMI)

Administer aspirin (oral 150-325 mg or IV if unable to swallow) immediately upon STEMI diagnosis, initiate a potent P2Y12 inhibitor (prasugrel 60 mg loading dose or ticagrelor), and pursue primary percutaneous coronary intervention (PCI) within 90 minutes of first medical contact—or fibrinolytic therapy within 30 minutes if PCI cannot be performed within 120 minutes. 1

Initial Pharmacotherapy (Administer Immediately)

Antiplatelet Therapy:

• Aspirin: 150-325 mg orally or IV (if patient cannot swallow) as soon as possible 1
• P2Y12 Inhibitor: Administer before or at the time of PCI 1
  • Prasugrel: 60 mg loading dose, then 10 mg daily (reduce to 5 mg daily if weight <60 kg) 2
  • Ticagrelor: Preferred alternative to prasugrel 1
  • Clopidogrel: Only if prasugrel or ticagrelor unavailable or contraindicated 1

Critical Caveat: Do NOT use prasugrel in patients with prior stroke/TIA, as it increases intracranial hemorrhage risk (4.2% thrombotic stroke + 2.3% ICH vs 1.2% with clopidogrel) 2. Generally avoid prasugrel in patients ≥75 years unless high-risk features (diabetes, prior MI) present 2.

Reperfusion Strategy Decision Algorithm

Step 1: Can Primary PCI Be Performed Within 120 Minutes of STEMI Diagnosis?

YES → Primary PCI (Preferred Strategy)

• Target: First medical contact to device time ≤90 minutes (≤60 minutes if presenting within 120 minutes of symptom onset or directly to PCI-capable hospital) 1
• Logistics: Transfer patient directly to catheterization laboratory, bypassing emergency department 1
• Anticoagulation: Administer heparin or bivalirudin (fondaparinux NOT recommended for primary PCI) 1

NO → Fibrinolytic Therapy (If <12 Hours from Symptom Onset)

• Target: Initiate within 30 minutes of STEMI diagnosis, preferably pre-hospital 1, 3
• Agent: Use fibrin-specific agent (tenecteplase, alteplase, or reteplase) 1, 3
• Adjunctive Therapy:
  • Aspirin (oral or IV) 1, 3
  • Clopidogrel in addition to aspirin 1, 3
  • Anticoagulation with enoxaparin IV followed by subcutaneous (preferred over unfractionated heparin) OR weight-adjusted UFH bolus + infusion 1, 3
  • Continue anticoagulation until revascularization or up to 8 days of hospitalization 1, 3

Post-Fibrinolysis Management Protocol

Immediate Actions:

• Transfer ALL patients to PCI-capable center immediately after fibrinolysis 1, 3

At 60-90 Minutes Post-Fibrinolysis:

• Assess ST-segment resolution in lead with greatest initial elevation 3

If <50% ST-Segment Resolution (Failed Fibrinolysis):

• Perform rescue PCI immediately 1, 3

If ≥50% ST-Segment Resolution (Successful Fibrinolysis):

• Perform angiography and PCI of infarct-related artery between 2-24 hours 1, 3

Emergency Angiography Indications (Perform Immediately Regardless of Fibrinolysis Success):

• Heart failure or cardiogenic shock 1, 3
• Hemodynamic instability 1, 3
• Electrical instability 1
• Worsening ischemia 1
• Recurrent ischemia or evidence of reocclusion 1, 3

Critical Time-Dependent Considerations

Reperfusion therapy is indicated for:

• Symptoms of ischemia ≤12 hours duration with persistent ST-elevation 1
• Consider reperfusion even >12 hours if clinical/ECG evidence of ongoing ischemia (symptom onset timing often unclear) 1

Do NOT perform routine PCI:

• In asymptomatic patients >48 hours after STEMI onset with occluded infarct-related artery 1, 3

Common Pitfalls to Avoid

Timing Errors:

• Do NOT delay fibrinolysis waiting for PCI if transfer time exceeds 120 minutes from diagnosis 1, 3
• First medical contact to ECG should be ≤10 minutes 1

Anticoagulation Mistakes:

• Do NOT use fondaparinux for primary PCI 1
• Do NOT combine fibrinolysis with planned immediate PCI (increases mortality) 3

Prasugrel-Specific Contraindications:

• Active bleeding 2
• History of TIA or stroke 2
• Weight <60 kg requires dose reduction to 5 mg maintenance 2
• Avoid if urgent CABG likely; discontinue ≥7 days before surgery if possible 2

Regional Network Approach

Optimal STEMI care requires:

• Pre-hospital networks designed to deliver reperfusion expeditiously 1
• Primary PCI-capable centers providing 24/7 service 1
• Direct catheterization laboratory transfer bypassing emergency department 1