What are the indications for thrombolysis in pulmonary embolism?

Indications for Thrombolysis in Pulmonary Embolism

Thrombolytic therapy is strongly indicated for patients with high-risk pulmonary embolism (PE) presenting with hemodynamic instability, defined as systolic blood pressure <90 mmHg or a decrease in systolic blood pressure ≥40 mmHg from baseline. 1, 2

Classification of PE and Thrombolysis Indications

High-Risk (Massive) PE

• Primary indication: Hemodynamic instability (systolic BP <90 mmHg or drop ≥40 mmHg from baseline) 1, 2
• Signs of cardiogenic shock or hypoperfusion 2
• Mortality risk without thrombolysis: up to 50% by 90 days 1
• Strong recommendation (Class I) by major guidelines 1

Intermediate-Risk (Submassive) PE

• Not routinely indicated but should be considered in:
  • Patients with evidence of right ventricular dysfunction AND myocardial injury 1, 2
  • Younger patients (≤75 years) with low bleeding risk 2
  • Patients showing clinical deterioration after starting anticoagulation 2
• Characterized by:
  • Normal blood pressure (systolic BP ≥90 mmHg)
  • Evidence of RV dysfunction on imaging (echocardiography)
  • Elevated cardiac biomarkers (troponin, BNP/NT-proBNP)

Low-Risk PE

• Thrombolysis not indicated 2, 3
• Normal hemodynamics
• No evidence of RV dysfunction or myocardial injury
• Excellent prognosis with standard anticoagulation alone 3

Contraindications to Thrombolysis

Absolute Contraindications

• Active internal bleeding
• Recent surgery or obstetrical delivery
• Previous intracranial hemorrhage
• Intracranial malignancy
• Stroke within the past 3 months 2

Relative Contraindications

• Thrombocytopenia or coagulopathy
• Severe hepatic or renal disease
• Pregnancy
• Current use of anticoagulants 2

Special Considerations

Pregnancy

• In pregnant women with acute PE and life-threatening hemodynamic instability, thrombolytic therapy is suggested in addition to anticoagulation (conditional recommendation) 1
• Limited evidence is based on case reports and case series 1

Elderly Patients

• Advanced age alone is not an absolute contraindication for high-risk PE 2
• Patients >75 years have significantly higher bleeding risk, particularly intracranial hemorrhage 2, 4
• Consider reduced-dose thrombolysis or alternative approaches in elderly patients 4

Alternative Approaches

• Surgical pulmonary embolectomy: recommended for patients with high-risk PE when thrombolysis is contraindicated or has failed 1
• Catheter-directed thrombolysis: may be considered in patients with high bleeding risk or failed systemic thrombolysis 1, 2

Risk-Benefit Assessment

Benefits of Thrombolysis

• In high-risk PE: Reduced mortality (OR 0.61; 95% CI 0.40-0.94) 5
• Reduced recurrence of PE (OR 0.54; 95% CI 0.32-0.91) 5
• More rapid resolution of pulmonary arterial thrombi 3
• Prevention of hemodynamic collapse in intermediate-risk patients 4

Risks of Thrombolysis

• Increased risk of major bleeding (OR 2.84; 95% CI 1.92-4.20) 5
• Increased risk of intracranial hemorrhage (OR 3.17; 95% CI 1.19-8.41) 1
• Higher risk in elderly patients, particularly those >75 years 4

Monitoring After Thrombolysis

• Continue full anticoagulation after thrombolysis 2
• Avoid antiplatelet drugs in the first 24 hours after thrombolysis 2
• Close monitoring for bleeding complications, particularly intracranial hemorrhage 2
• Monitor for clinical improvement in hemodynamic parameters

In summary, while thrombolysis clearly benefits patients with high-risk PE presenting with hemodynamic instability, its use in intermediate-risk PE requires careful patient selection based on age, bleeding risk, and clinical status. The decision to administer thrombolytic therapy must weigh the potential mortality benefit against the significant increased risk of major bleeding.