Recommended Thrombolytic Regimen for Myocardial Infarction (MI)
For patients with STEMI who cannot receive primary PCI within 120 minutes of first medical contact, a fibrin-specific agent (tenecteplase, alteplase, or reteplase) should be administered as soon as possible, preferably in the pre-hospital setting. 1
Primary Reperfusion Strategy Decision
Primary PCI (Preferred when available in timely manner)
- Primary PCI is the preferred reperfusion strategy when it can be performed:
Fibrinolytic Therapy (When timely PCI unavailable)
- Indicated when primary PCI cannot be performed within 120 minutes of STEMI diagnosis 2
- Should be initiated as soon as possible after diagnosis, preferably pre-hospital 1
- Most beneficial when administered within 3 hours of symptom onset 1
Recommended Fibrinolytic Agents
Fibrin-Specific Agents (Preferred)
Tenecteplase (TNKase):
- Weight-based single bolus dosing
- Easier to administer in pre-hospital setting
- Contraindicated in patients with active internal bleeding, history of cerebrovascular accident, or severe uncontrolled hypertension 3
Alteplase (tPA):
- Administered as accelerated infusion
- Dose should be adjusted for patients weighing <67 kg to reduce ICH risk 1
Reteplase:
- Double-bolus administration
Non-Fibrin-Specific Agents (Less preferred)
- Streptokinase: Less effective than fibrin-specific agents and associated with higher rates of allergic reactions
Adjunctive Therapy with Fibrinolysis
Antiplatelet Therapy
- Aspirin: 162-325 mg (chewable, non-enteric coated) as initial dose, followed by 75-100 mg daily 1
- Clopidogrel: Required in addition to aspirin 1
Anticoagulation
- Enoxaparin: IV bolus followed by subcutaneous (preferred over UFH) 1
- Unfractionated Heparin (UFH): Weight-adjusted IV bolus followed by infusion 1
- Fondaparinux: Not recommended for primary PCI due to risk of catheter thrombosis 1
Post-Fibrinolysis Management
Transfer Strategy
- All patients should be transferred to a PCI-capable center immediately after fibrinolysis 1
- Angiography and PCI of the infarct-related artery (if indicated) should be performed between 2-24 hours after successful fibrinolysis 1
Rescue PCI Indications
- Failed fibrinolysis (<50% ST-segment resolution at 60-90 minutes) 1
- Hemodynamic or electrical instability 1
- Worsening ischemia 1
- Heart failure or cardiogenic shock 1
- Recurrent ischemia or evidence of reocclusion after initially successful fibrinolysis 1
Special Considerations
Risk Assessment for Intracranial Hemorrhage (ICH)
- Risk factors for ICH include 1:
- Age >65 years
- Weight <70 kg
- Hypertension on admission
- Use of tissue plasminogen activator
Time-Dependent Efficacy
- The benefit of fibrinolytic therapy is time-dependent, with greatest benefit when administered within 3 hours of symptom onset 1
- Beyond 3 hours, primary PCI is superior to fibrinolysis for myocardial salvage 1
Common Pitfalls and Caveats
- Delayed Administration: Every effort should be made to minimize the time from symptom onset to treatment, as efficacy decreases with time
- Contraindications: Always check for contraindications to thrombolytic therapy, particularly active bleeding, recent stroke, or uncontrolled hypertension 3
- Inadequate Anticoagulation: Ensure appropriate anticoagulation is maintained until revascularization or for the duration of hospital stay (up to 8 days) 1
- Missed Rescue PCI: Monitor for signs of failed fibrinolysis and arrange for rescue PCI if needed
- Inappropriate Agent Selection: Use fibrin-specific agents rather than streptokinase when possible 1
- Bleeding Risk: Avoid unnecessary arterial or venous punctures and intramuscular injections to minimize bleeding risk 3
By following this algorithm, clinicians can optimize outcomes for MI patients requiring thrombolytic therapy, with the understanding that primary PCI remains the preferred reperfusion strategy when timely access is available.