Should I perform thrombolysis (thrombolytic therapy) with this ECG indicating STEMI (ST-Elevation Myocardial Infarction)?

Thrombolysis Decision-Making in STEMI

Thrombolysis should be administered for STEMI when primary PCI cannot be performed within 120 minutes of first medical contact, provided the patient has symptoms within 12 hours of onset and no contraindications to fibrinolytic therapy. 1

Assessment of ECG Criteria for Thrombolysis

• Indications for thrombolysis based on ECG:

  • ST elevation ≥0.1 mV (1 mm) in at least 2 contiguous precordial leads or 2 adjacent limb leads 1
  • New or presumably new left bundle branch block 1
  • True posterior (inferobasal) MI with ST depression in anterior leads 1

• Contraindications for thrombolysis based on ECG:

  • ST depression only (except when true posterior MI is suspected or when associated with ST elevation in lead aVR) 1
  • Non-diagnostic ECG changes without clear ST elevation 1

Time-Based Decision Algorithm

1. If symptom onset <12 hours and:

   • Primary PCI available within 120 minutes of first medical contact → Choose PCI
   • Primary PCI NOT available within 120 minutes → Administer thrombolysis within 30 minutes of first medical contact 1

2. If symptom onset 12-24 hours and:

   • Ongoing ischemic symptoms AND large area of myocardium at risk or hemodynamic instability → Consider thrombolysis if PCI unavailable 1
   • No ongoing symptoms → Thrombolysis not indicated 1

3. If symptom onset >24 hours:

   • Thrombolysis not indicated regardless of ECG findings 1

Fibrinolytic Agent Selection

If thrombolysis is indicated, select a fibrin-specific agent:

• Tenecteplase (TNK-tPA): Single IV weight-based bolus (preferred for ease of administration)
• Reteplase (rPA): 10 U + 10 U IV boluses given 30 minutes apart
• Alteplase (tPA): 90-minute weight-based infusion 1

Post-Thrombolysis Management

• Transfer to a PCI-capable center immediately after fibrinolysis 1
• Perform emergency angiography and PCI if:
  • Fibrinolysis has failed (<50% ST-segment resolution at 60-90 minutes)
  • Hemodynamic or electrical instability develops
  • Worsening ischemia occurs 1
• If fibrinolysis is successful, perform angiography between 2-24 hours after 1

Important Considerations

• The mortality benefit of thrombolysis is time-dependent and most effective when administered within the first 1-2 hours of symptom onset 1
• Patients with higher ischemia grades on ECG (Grade 3 ischemia with terminal QRS distortion) have higher mortality and may benefit more from primary PCI when available early 2
• Patients with prior myocardial infarction may have less clear ECG findings but higher mortality, requiring careful assessment 3
• Mortality increases significantly with symptom duration in all patients, emphasizing the importance of rapid decision-making 2

Pitfalls to Avoid

• Do not administer thrombolytics to patients with only ST depression (unless posterior MI is suspected) 1
• Do not delay thrombolysis when PCI cannot be performed within the recommended timeframe 1
• Do not overlook contraindications to thrombolysis (prior intracranial hemorrhage, recent stroke, active bleeding, etc.) 1
• Do not forget to transfer patients to a PCI-capable center after thrombolysis for potential rescue PCI 1

Remember that while primary PCI is generally superior to thrombolysis when performed in a timely manner, thrombolysis remains a critical reperfusion strategy when PCI is not readily available, as timely reperfusion is the key determinant of outcomes in STEMI.