What are contraindications to fibrinolytic therapy?

Symptomatic intracerebral hemorrhage, the most feared complication of fibrinolytic therapy, occurs in about 5-6% of ischemic stroke patients treated with rtPA. Understanding what are contraindications to fibrinolytic therapy is crucial for minimizing this risk while providing life-saving treatment.

Quick Summary

A detailed review of the absolute and relative contraindications for using fibrinolytic agents. This information covers patient assessment for ischemic stroke, STEMI, and other thrombotic events, focusing on bleeding risk factors.

Key Points

• Absolute vs. Relative: Contraindications are divided into 'absolute' (therapy is forbidden) and 'relative' (requires risk-benefit analysis) categories.

• Bleeding is the Core Risk: The primary reason for nearly all contraindications is the heightened risk of severe internal bleeding, especially intracranial hemorrhage.

• Brain History is Critical: Any prior intracranial hemorrhage, known brain tumors, or vascular lesions are absolute contraindications.

• Recent Events Matter: Recent major surgery, significant trauma, or an ischemic stroke within the past three months are typically absolute contraindications.

• Blood Pressure Control: Severe, uncontrolled hypertension (e.g., >185/110 mmHg for stroke) is a key contraindication that must be managed before treatment can be considered.

• Active Bleeding Prohibits Use: Any active internal bleeding or known bleeding disorders are absolute contraindications to fibrinolysis.

• Patient-Specific Assessment: Relative contraindications like pregnancy, current anticoagulant use, or recent non-cranial surgery require careful clinical judgment.

Understanding Fibrinolytic Therapy and Its Risks

Fibrinolytic therapy, also known as thrombolytic therapy, uses 'clot-busting' drugs to dissolve blood clots that cause life-threatening conditions like ST-elevation myocardial infarction (STEMI), acute ischemic stroke, and pulmonary embolism. Medications such as alteplase, reteplase, and tenecteplase activate plasminogen to form plasmin, which breaks down clots and restores blood flow. While beneficial, this treatment carries a significant risk of internal bleeding, most notably intracranial hemorrhage (ICH). Therefore, a careful screening process is vital to identify patients for whom the risks outweigh the benefits. These risk factors are classified as absolute or relative contraindications.

Absolute Contraindications: When Fibrinolysis is Prohibited

Absolute contraindications are conditions where the risk of severe bleeding, especially ICH, is so high that fibrinolytic therapy should not be given.

For a detailed list of absolute contraindications, refer to {Link: UpToDate https://www.uptodate.com/contents/acute-st-elevation-myocardial-infarction-management-of-fibrinolysis}. For acute ischemic stroke patients, specific additional criteria apply. Severe uncontrolled hypertension (Systolic >185 mmHg or Diastolic >110 mmHg) that cannot be managed is an absolute contraindication, as is a blood glucose below 50 mg/dL. Evidence of a large, established infarct on CT scan (hypodensity in >1/3 of a hemisphere) also precludes fibrinolysis due to high hemorrhage risk.

Relative Contraindications: A Risk-Benefit Analysis

Relative contraindications increase the risk of bleeding but do not automatically exclude a patient. The decision requires careful assessment of potential benefits versus increased risks. For a list of common relative contraindications, consult {Link: ACLS Medical Training https://www.aclsmedicaltraining.com/fibrinolytic-checklist/}.

Comparison of Contraindications

Feature	Absolute Contraindication	Relative Contraindication
Definition	A condition that strictly prohibits the use of fibrinolytic therapy due to an unacceptably high risk of harm.	A condition that increases the risk of complications, requiring careful clinical judgment to weigh risks versus benefits.
Prior ICH	Any history of intracranial hemorrhage.	N/A (This is always absolute).
Blood Pressure	Severe uncontrolled hypertension unresponsive to emergency therapy (e.g., SBP >185 for stroke).	History of chronic, severe, poorly controlled hypertension; or SBP >180 / DBP >110 mmHg on presentation that is responsive to medication.
Recent Stroke	Ischemic stroke within 3 months (for non-stroke indications).	Ischemic stroke >3 months ago.
Trauma/Surgery	Significant head/facial trauma within 3 months; intracranial/spinal surgery within 2 months.	Major surgery (non-cranial) within 3 weeks; traumatic CPR (>10 min).
Anticoagulation	Active bleeding diathesis, platelet count <100,000.	Current use of anticoagulants with INR > 1.7.
Clinical Action	Withhold fibrinolytic therapy.	Proceed with caution after a thorough risk-benefit assessment.

Conclusion

Deciding to use fibrinolytic therapy requires a critical, time-sensitive clinical judgment. The categorization into absolute and relative contraindications provides a crucial framework to balance the potential benefits of dissolving a clot against the significant risk of bleeding. A thorough patient history, physical examination, and rapid diagnostic tests are essential for applying these criteria correctly.

For more detailed guidelines, consult the American Heart Association/American Stroke Association resources.

AHA/ASA Guidelines for Early Management of Acute Ischemic Stroke

Frequently Asked Questions

What is the main difference between an absolute and a relative contraindication for fibrinolytic therapy?

An absolute contraindication is a condition that makes the use of fibrinolytic therapy unacceptably dangerous and is therefore prohibited (e.g., any prior brain hemorrhage). A relative contraindication increases the risk, requiring a careful risk-versus-benefit analysis by the doctor (e.g., pregnancy or controlled hypertension).

Why is a history of intracranial hemorrhage an absolute contraindication?

A prior intracranial hemorrhage indicates a pre-existing weakness in the brain's vascular system. Administering a 'clot-busting' drug creates a very high risk of causing a new, potentially fatal bleed in the same or a new location.

Can a patient with high blood pressure receive fibrinolytic therapy?

It depends. If the blood pressure is severely uncontrolled and cannot be lowered with emergency medication (e.g., >185/110 mmHg in a stroke patient), it is an absolute contraindication. If the high blood pressure can be brought down to an acceptable level, it may be considered a relative contraindication, and therapy might proceed.

Are older patients automatically excluded from receiving fibrinolysis?

No, advanced age (>75 years) is generally considered a relative contraindication, not an absolute one. The decision is based on the individual patient's overall health, potential benefit, and other risk factors, not just their age.

What happens if a patient is taking a blood thinner like warfarin?

Current use of an anticoagulant like warfarin is a relative contraindication. Doctors will check the patient's international normalized ratio (INR); if it is elevated above a certain threshold (often >1.7), the risk of bleeding is considered too high, and fibrinolysis is typically avoided.

What is the biggest risk associated with fibrinolytic therapy?

The single biggest and most feared risk is internal bleeding. Specifically, symptomatic intracranial hemorrhage (bleeding into the brain) is the most devastating complication.

What are the main alternatives if a patient has contraindications to fibrinolytic therapy?

For a heart attack (STEMI), the primary alternative is percutaneous coronary intervention (PCI), or angioplasty. For an ischemic stroke, the main alternative is mechanical thrombectomy, a procedure where the clot is physically removed using a catheter-based device.