When should a patient with atrial fibrillation (A fib) not be anticoagulated?

When to Withhold Anticoagulation in Atrial Fibrillation

Patients with atrial fibrillation should not be anticoagulated if they have absolute contraindications to anticoagulation, most commonly active bleeding, recent intracranial hemorrhage, or severe bleeding risk that outweighs stroke prevention benefit. 1

Absolute Contraindications to Anticoagulation

The following are clear reasons to withhold anticoagulation:

Active Bleeding

• Active bleeding requires immediate interruption of anticoagulation until the bleeding source is identified and resolved. 1
• This includes major gastrointestinal bleeding, intracranial hemorrhage, or any life-threatening hemorrhage 2, 3

History of Intracranial Hemorrhage

• Prior intracranial hemorrhage is the most common absolute contraindication, accounting for 60% of patients ineligible for any anticoagulant. 2
• In patients with recent intracerebral hemorrhage and AF, management of uncontrolled hypertension must be addressed before considering any antithrombotic treatment 1, 4
• Cerebral imaging (CT or MRI) should be performed to exclude hemorrhage before starting anticoagulation 1

Mechanical Heart Valves Requiring Specific Therapy

• Dabigatran (a direct thrombin inhibitor) must not be used in patients with mechanical heart valves. 1
• These patients require warfarin specifically, not DOACs 1

Very Low Stroke Risk Patients

Young Patients with Lone Atrial Fibrillation

• Patients under 60-65 years of age without heart disease or risk factors for thromboembolism (lone AF) do not require anticoagulation. 1, 5
• More specifically, patients with a CHA₂DS₂-VASc score of 0 in men can reasonably omit anticoagulation 1
• For nonvalvular AF with CHA₂DS₂-VASc score of 0, it is reasonable to omit antithrombotic therapy 1

Relative Contraindications Requiring Careful Assessment

Patient Refusal or Inability to Comply

• Clear patient refusal to take oral anticoagulation or documented inability to cope with anticoagulation monitoring is a valid reason to withhold therapy. 1
• In such cases, aspirin may be considered for stroke prevention, though it offers less benefit 1

Severe Renal Impairment

• Direct thrombin inhibitor dabigatran and factor Xa inhibitor rivaroxaban are not recommended in patients with end-stage chronic kidney disease (CrCl <15 mL/min) or on dialysis due to lack of evidence. 1
• For patients with AF and end-stage CKD or on hemodialysis with CHA₂DS₂-VASc score ≥2, warfarin (INR 2.0-3.0) or apixaban may be reasonable alternatives 1

Critical Management Principles

Bleeding Risk Assessment

• Assessment of bleeding risk should be performed, but bleeding risk scores should NOT be used to decide whether to start or withdraw anticoagulation—they are meant to identify modifiable risk factors, not to withhold therapy. 1
• The HAS-BLED score can identify high-risk patients (score >3) who need careful monitoring, but this should prompt caution and regular review, not automatic withholding of anticoagulation 1
• Bleeding risk with aspirin should be considered similar to warfarin, especially in the elderly, so aspirin is not a "safer" alternative in high bleeding risk patients. 1

Temporary Interruption Scenarios

• For surgical or diagnostic procedures with bleeding risk, anticoagulation may be interrupted temporarily (up to 48 hours of subtherapeutic anticoagulation) without bridging therapy in patients without mechanical valves or high thromboembolism risk. 1
• Patients with mechanical prosthetic valves or high thromboembolism risk require bridging with therapeutic LMWH or unfractionated heparin during interruption 1

Post-Stroke Management

• In the presence of hemorrhagic stroke, anticoagulation should not be given. 1
• With large cerebral infarction, delaying anticoagulation initiation should be considered due to hemorrhagic transformation risk 1
• In the absence of hemorrhage, oral anticoagulation should be considered approximately 2 weeks after ischemic stroke 1

Common Pitfalls to Avoid

Do not withhold anticoagulation based solely on:

• Advanced age alone—age ≥75 years increases both stroke and bleeding risk, but anticoagulation remains beneficial if stroke risk exceeds bleeding risk 1, 4
• Elevated bleeding risk scores without absolute contraindications—these patients often benefit most from anticoagulation 1
• Fall risk or dementia—while these increase bleeding risk, the stroke prevention benefit typically outweighs the risk 2

Key principle: Only approximately 2.2% of AF patients have true absolute contraindications to all anticoagulation 2. The vast majority of patients should receive anticoagulation based on their CHA₂DS₂-VASc score, with careful attention to modifiable bleeding risk factors rather than blanket withholding of therapy.