Is fibrinolysis (breakdown of fibrin) done in Non-ST-Elevation Myocardial Infarction (NSTEMI)?

Fibrinolysis is Not Indicated in NSTEMI

Fibrinolysis should not be used in patients with Non-ST-Elevation Myocardial Infarction (NSTEMI) as it has no significant beneficial effect and actually increases the risk of myocardial infarction. 1

Evidence Against Fibrinolysis in NSTEMI

Multiple high-quality guidelines and clinical trials have consistently demonstrated that fibrinolytic therapy has no role in NSTEMI management:

• The ACC/AHA guidelines explicitly state that fibrinolysis should not be used in NSTEMI patients (Class III: Harm recommendation with Level of Evidence: A) 1

• Multiple landmark trials (TIMI 11B, ISIS-2, and GISSI 1) clearly demonstrated the failure of intravenous fibrinolytic therapy to improve clinical outcomes in patients without ST-segment elevation 1

• A meta-analysis of fibrinolytic therapy in UA/NSTEMI patients showed no benefit compared to standard therapy, and actually demonstrated an increased risk of myocardial infarction with fibrinolysis 1

Appropriate Management Strategy for NSTEMI

Instead of fibrinolysis, the recommended treatment approach for NSTEMI includes:

1. Antiplatelet therapy:

   • Aspirin
   • P2Y12 inhibitor (clopidogrel, ticagrelor, or prasugrel)

2. Anticoagulation:

   • Unfractionated heparin, low molecular weight heparin, fondaparinux, or bivalirudin 1, 2

3. Risk stratification and invasive strategy decisions:

   • Early invasive strategy for high-risk patients (refractory angina, hemodynamic instability, electrical instability) 1
   • Either early invasive or initially conservative strategy for stabilized patients based on risk assessment 1

Why Fibrinolysis Works in STEMI but Not NSTEMI

The pathophysiological difference between STEMI and NSTEMI explains why fibrinolysis is beneficial in STEMI but harmful in NSTEMI:

• STEMI: Complete coronary occlusion with thrombus formation that can be dissolved by fibrinolytic agents 3, 4
• NSTEMI: Partial or intermittent coronary occlusion, often with plaque rupture and microemboli, where fibrinolysis may destabilize plaques without improving flow 2

Common Pitfalls to Avoid

1. Do not confuse NSTEMI with STEMI management: Fibrinolysis is appropriate for STEMI when timely PCI is unavailable (within 120 minutes of first medical contact) 3, but is contraindicated in NSTEMI.

2. Do not delay appropriate NSTEMI therapy: Focus on antiplatelet therapy, anticoagulation, and risk stratification for potential invasive management rather than considering fibrinolysis.

3. Do not misinterpret ST depression: The presence of ST depression on ECG should not prompt consideration of fibrinolysis unless there is evidence of a true posterior MI with ST elevation 3.

In conclusion, fibrinolysis has a clear Class III: Harm recommendation in NSTEMI management and should be avoided in favor of evidence-based antiplatelet therapy, anticoagulation, and appropriate risk stratification for invasive management.