What is the dose of Tissue Plasminogen Activator (TPA) for a patient with ST-Elevation Myocardial Infarction (STEMI) complicated by cardiac arrest?

TPA Dosing for STEMI Complicated by Cardiac Arrest

For STEMI patients with cardiac arrest, the recommended fibrinolytic therapy is a fibrin-specific agent (tenecteplase, alteplase, or reteplase) administered at standard dosing, with tenecteplase being preferred due to its ease of administration as a single bolus.

Fibrinolytic Agent Options and Dosing

Preferred Agent: Tenecteplase (TNK-tPA)

• Single bolus IV administration:
  • Weight-based dosing:
    • <60 kg: 30 mg
    • 60-69 kg: 35 mg
    • 70-79 kg: 40 mg
    • 80-89 kg: 45 mg
    • ≥90 kg: 50 mg
  • Important: Consider half-dose tenecteplase in patients ≥75 years of age 1

Alternative Agents:

• Alteplase (tPA):

  • 15 mg IV bolus
  • 0.75 mg/kg over 30 minutes (maximum 50 mg)
  • 0.5 mg/kg over next 60 minutes (maximum 35 mg)
  • Total dose not to exceed 100 mg

• Reteplase (rPA):

  • 10 units IV bolus
  • Followed by 10 units IV bolus 30 minutes later

Clinical Decision Algorithm

1. Confirm STEMI diagnosis (if possible during resuscitation)

   • 12-lead ECG showing ST elevation
   • Consider point-of-care ultrasound if available

2. Assess for contraindications to fibrinolysis 1:

   • Absolute contraindications:
     • Prior intracranial hemorrhage
     • Known cerebral vascular lesion
     • Malignant intracranial neoplasm
     • Ischemic stroke within 3 months
     • Suspected aortic dissection
     • Active bleeding or bleeding diathesis
     • Significant closed-head/facial trauma within 3 months
     • Intracranial/intraspinal surgery within 2 months
     • Severe uncontrolled hypertension

3. Administer fibrinolytic therapy if:

   • STEMI is confirmed
   • No contraindications exist
   • Primary PCI is not immediately available
   • Patient has high likelihood of thrombotic etiology

4. Adjunctive therapies:

   • Aspirin 162-325 mg (chewed) 1
   • Clopidogrel:
     • Age ≤75 years: 300 mg loading dose
     • Age >75 years: 75 mg (no loading dose) 1
   • Anticoagulation:
     • Enoxaparin (preferred):
       • Age <75 years: 30 mg IV bolus, then 1 mg/kg SC every 12 hours
       • Age ≥75 years: No bolus, 0.75 mg/kg SC every 12 hours
       • If CrCl <30 mL/min: 1 mg/kg SC every 24 hours 1
     • OR UFH: 60 U/kg IV bolus (max 4000 U), then 12 U/kg/h (max 1000 U/h) to maintain aPTT 1.5-2.0× control 1

Special Considerations for Cardiac Arrest

1. Timing of administration:

   • Administer during brief intermittent phases of spontaneous circulation when possible 2
   • May consider administration during ongoing CPR in select cases with high likelihood of thrombotic etiology

2. Post-resuscitation care:

   • Immediate angiography and PCI is indicated in patients with STEMI and cardiac arrest if coronary anatomy is suitable 1
   • Consider therapeutic hypothermia (32-34°C) for comatose survivors 1, 3

Important Caveats

• Cardiac arrest patients with STEMI have significantly higher mortality (28.8% vs 4.0%) compared to non-cardiac arrest STEMI patients 4
• Cardiogenic shock and cardiac arrest frequently coexist, requiring aggressive management of both conditions 4
• The combination of therapeutic hypothermia with primary PCI is feasible and safe in patients resuscitated after cardiac arrest due to STEMI 3
• Patients with STEMI and cardiac arrest should be transferred to PCI-capable centers whenever possible 5

Pitfalls to Avoid

• Delaying fibrinolysis when primary PCI is not immediately available
• Administering fibrinolytics when absolute contraindications exist
• Failing to provide appropriate antiplatelet and anticoagulant therapy
• Neglecting to arrange for urgent transfer to a PCI-capable facility after fibrinolysis
• Overlooking the need for therapeutic hypothermia in comatose survivors

Remember that immediate angiography and PCI is the preferred strategy for STEMI patients with cardiac arrest when rapidly available, with fibrinolytic therapy being a critical alternative when timely PCI is not possible 1.