When is thrombolysis (breakdown of blood clots) recommended for patients with pulmonary embolism (blockage of an artery in the lungs)?

Thrombolysis in Pulmonary Embolism

Thrombolytic therapy is strongly recommended for patients with high-risk pulmonary embolism presenting with cardiogenic shock and/or persistent arterial hypotension, but should not be routinely used in hemodynamically stable patients with intermediate or low-risk PE. 1

Risk Stratification for Thrombolysis

Pulmonary embolism severity is classified into three categories that guide treatment decisions:

High-Risk PE (Massive PE)

• Characterized by hemodynamic instability with systolic hypotension (<90 mmHg or drop ≥40 mmHg) or cardiogenic shock 1
• Systemic thrombolytic therapy is recommended (Class I recommendation) unless absolute contraindications exist 1
• The recommended dose for alteplase (tPA) is 100 mg administered by IV infusion over 2 hours 2
• Parenteral anticoagulation should be initiated near the end of or immediately following thrombolysis 2

Intermediate-Risk PE (Submassive PE)

• Characterized by right ventricular dysfunction and/or myocardial injury but without hemodynamic instability 1
• Routine use of thrombolysis is NOT recommended (Class III recommendation) 1
• Rescue thrombolytic therapy is recommended only if clinical deterioration with hemodynamic compromise occurs during anticoagulation treatment 1
• Meta-analyses suggest potential mortality benefits in selected intermediate-risk patients, but with increased bleeding risk 3

Low-Risk PE

• Hemodynamically stable without evidence of right ventricular dysfunction or myocardial injury 1
• Thrombolytic therapy should NOT be used (Class III recommendation) 1
• Standard anticoagulation is the treatment of choice 1

Alternative Approaches When Thrombolysis is Contraindicated

For high-risk PE patients with contraindications to thrombolysis or in whom thrombolysis has failed:

• Surgical pulmonary embolectomy is recommended (Class I recommendation) 1
• Percutaneous catheter-directed treatment should be considered (Class IIa recommendation) 1
• Extracorporeal membrane oxygenation (ECMO) may be considered in combination with surgical embolectomy or catheter-directed treatment for patients with refractory circulatory collapse (Class IIb recommendation) 1

Contraindications to Thrombolysis

Absolute contraindications include:

• History of hemorrhagic stroke or stroke of unknown origin
• Ischemic stroke within previous 6 months
• Central nervous system neoplasm
• Major trauma, surgery, or head injury within previous 3 weeks
• Active bleeding 1

Relative contraindications include:

• Transient ischemic attack within previous 6 months
• Oral anticoagulation
• Pregnancy or first post-partum week
• Non-compressible puncture sites
• Traumatic resuscitation
• Refractory hypertension 1

Bleeding Risk Considerations

• Major bleeding occurs in approximately 9.24% of patients receiving thrombolysis versus 3.42% with anticoagulation alone (NNH = 18) 3
• Intracranial hemorrhage risk is significantly higher with thrombolysis (1.46% vs 0.19%, NNH = 78) 3
• Bleeding risk is lower in patients ≤65 years of age 3

Multidisciplinary Approach

For complex cases, especially those with intermediate-high risk PE, involvement of a Pulmonary Embolism Response Team (PERT) is encouraged to enhance clinical decision-making through real-time multidisciplinary consultation 1

Key Practice Points

• Initiate unfractionated heparin without delay in patients with high-risk PE 1
• Reserve thrombolysis primarily for high-risk PE with hemodynamic instability 1
• For intermediate-risk PE, start with anticoagulation and monitor closely; use thrombolysis only if clinical deterioration occurs 1
• Consider surgical embolectomy or catheter-directed treatment when thrombolysis is contraindicated or has failed 1
• Avoid routine use of inferior vena cava filters; consider only in patients with absolute contraindications to anticoagulation or recurrent PE despite therapeutic anticoagulation 1