What is Fibrinolytic Therapy?
Fibrinolytic therapy is a treatment that uses medications to dissolve blood clots. It is primarily used for high-risk or massive pulmonary embolism (PE), characterized by hemodynamic instability. While it can rapidly break down clots and potentially save lives in urgent situations, it also carries a significant risk of serious bleeding. Therefore, identifying and understanding contraindications is crucial.
Absolute Contraindications
Absolute contraindications mean fibrinolytic therapy should not be given because the risk of severe, often life-threatening bleeding (especially in the brain) is too high.
These include prior intracranial hemorrhage, known structural lesions in the skull, known malignant intracranial neoplasm, and ischemic stroke within the last 3 months. Other absolute contraindications are suspected aortic dissection, active bleeding (not including menstruation), and known bleeding disorders. Recent surgery on the brain or spine, significant head or face trauma within the past 3 months, recent gastrointestinal bleeding within the past 21 days (which may be relative depending on severity), and vascular punctures that cannot be compressed are also listed as absolute contraindications.
Relative Contraindications
Relative contraindications require a careful evaluation of the potential benefits against the risks of bleeding. The decision to use fibrinolytic therapy in these situations is made on a case-by-case basis.
- Age over 75 years, as this increases the risk of intracranial bleeding
- Severe, uncontrolled high blood pressure (systolic >180 mmHg or diastolic >110 mmHg)
- Currently taking anticoagulant medications
- Pregnancy, due to risks for both mother and fetus
- Traumatic or prolonged cardiopulmonary resuscitation (CPR)
- Recent internal bleeding (within the last 2 to 4 weeks)
- Major surgery within the last 3 weeks
- Diabetic hemorrhagic retinopathy
- Dementia
- Ischemic stroke more than 3 months ago
Comparison of Absolute vs. Relative Contraindications
The key difference lies in the level of bleeding risk and the resulting clinical decision.
| Feature | Absolute Contraindications | Relative Contraindications |
|---|---|---|
| Risk Level | High, often life-threatening risk of bleeding. | Increased risk of bleeding, but manageable in some cases. |
| Clinical Action | Therapy is not administered under any circumstances. | Therapy may be considered after careful risk-benefit analysis based on PE severity. |
| Examples | Prior intracranial hemorrhage, known brain tumor, active bleeding, recent severe head trauma. | Advanced age, uncontrolled hypertension, current anticoagulant use, recent surgery (>3 weeks). |
| Patient Safety | The risk of hemorrhage is so high that the potential benefit is outweighed. | The decision depends on balancing the PE risk (mortality, instability) vs. bleeding risk. |
Weighing Risks and Benefits
For high-risk, unstable PE, the risk of death from the embolism is high, often justifying fibrinolysis if there are no absolute contraindications. For intermediate-risk PE, where patients are stable but show signs of right heart strain, the decision is more complex. Studies like the PEITHO trial show that while fibrinolysis may prevent worsening, it also increases the risk of major bleeding. Therefore, in intermediate-risk cases, less aggressive approaches are often preferred.
Alternative Treatment Options
When fibrinolytic therapy is not an option due to contraindications, or in certain intermediate-risk scenarios, other treatments can address the clot:
- Surgical Pulmonary Embolectomy: A surgical procedure to remove the clot, typically for unstable patients with contraindications to fibrinolysis.
- Catheter-Directed Therapy (CDT): Minimally invasive techniques to deliver clot-dissolving drugs directly to the clot or use devices to remove it, potentially reducing systemic bleeding risk.
- Mechanical Thrombectomy: Using catheters and devices to physically remove the clot.
- Anticoagulation: Standard treatment for low-risk and most intermediate-risk PE, preventing clot growth and new clots while the body naturally dissolves the existing one.
Conclusion
Fibrinolytic therapy is a powerful tool for life-threatening PE, but its use is strictly limited by contraindications. These contraindications, especially the absolute ones, are primarily due to the high risk of severe bleeding. Clinicians must carefully assess each patient's risks and the severity of their PE to determine the safest and most effective treatment, considering alternative options when fibrinolysis is contraindicated.
