What is the recommended anticoagulation therapy for patients with atrial fibrillation (AF)?

Anticoagulation for Atrial Fibrillation

For patients with atrial fibrillation and elevated stroke risk (CHA₂DS₂-VASc score ≥2 in men or ≥3 in women), direct oral anticoagulants (DOACs) are recommended over warfarin, with apixaban 5 mg twice daily being the preferred agent due to superior efficacy and safety profile. 1, 2

Risk Stratification Algorithm

Use the CHA₂DS₂-VASc score to determine anticoagulation need: 1, 2

• CHA₂DS₂-VASc = 0 in men or 1 in women (sex score only): No anticoagulation recommended 1, 2
• CHA₂DS₂-VASc = 1 in men or 2 in women: Oral anticoagulation recommended over no therapy 1
• CHA₂DS₂-VASc ≥2 in men or ≥3 in women: Oral anticoagulation strongly recommended 1, 2

The CHA₂DS₂-VASc scoring system includes: congestive heart failure (1 point), hypertension (1 point), age ≥75 years (2 points), diabetes (1 point), prior stroke/TIA (2 points), vascular disease (1 point), age 65-74 years (1 point), and female sex (1 point). 1, 3

First-Line Anticoagulant Selection

DOACs are preferred over warfarin for all eligible patients with non-valvular atrial fibrillation: 1, 2

DOAC Options (in order of preference based on efficacy and safety):

1. Apixaban 5 mg twice daily - Ranked highest for most outcomes including stroke prevention, major bleeding reduction, and mortality benefit 1, 4, 5

   • Reduces stroke/systemic embolism by 21% compared to warfarin 4
   • Reduces major bleeding by 31% compared to warfarin 4
   • Demonstrates mortality benefit (3.52% vs 3.94%/year with warfarin) 5
   • Preferred for patients with prior gastrointestinal bleeding 2

2. Dabigatran 150 mg twice daily - Consider for patients with high embolic risk and low bleeding risk 1, 6

   • Reduces stroke/systemic embolism by 35% compared to warfarin 4
   • Similar major bleeding rates to warfarin but higher than apixaban 4
   • Reserve for patients with high thromboembolic risk (e.g., prior stroke on other anticoagulants, left atrial appendage thrombus) 6

3. Edoxaban 60 mg once daily - Alternative option with once-daily dosing 1, 4

   • Reduces major bleeding by 22% compared to warfarin 4
   • Less effective than dabigatran 150 mg for stroke prevention 4

4. Rivaroxaban 20 mg once daily - Alternative option but higher bleeding risk 1, 4

   • Non-inferior to warfarin for stroke prevention 5
   • Higher major bleeding risk than apixaban (45% increased risk) 4

Warfarin Indications (Target INR 2.0-3.0):

Warfarin is the only option for: 1, 2, 7

• Mechanical heart valves 1, 7
• Moderate-to-severe mitral stenosis 1, 2
• End-stage renal disease or dialysis 3

For warfarin therapy, maintain INR 2.0-3.0 with time in therapeutic range (TTR) ≥70%, checking INR weekly during initiation and monthly when stable. 1, 7

Special Clinical Scenarios

High Bleeding Risk Patients:

Use apixaban 5 mg twice daily, edoxaban 60 mg once daily, or dabigatran 110 mg twice daily - these agents demonstrate significantly less major bleeding, particularly intracranial hemorrhage, compared to warfarin. 2, 3

Cardioversion Management:

• AF duration ≤48 hours: Start therapeutic anticoagulation immediately and proceed with cardioversion, continuing anticoagulation for at least 4 weeks post-cardioversion 2, 3
• AF duration >48 hours or unknown: Therapeutic anticoagulation for 3 weeks before cardioversion, then continue for at least 4 weeks after 3
• Hemodynamically unstable: Proceed with urgent cardioversion without delay, start anticoagulation as soon as possible, continue for at least 4 weeks 2

Long-term anticoagulation decisions after cardioversion are based on CHA₂DS₂-VASc score, not whether sinus rhythm was restored. 2, 3

Renal Impairment:

Dose-adjust DOACs based on creatinine clearance; warfarin is preferred for patients on dialysis. 3 Evaluate renal function before starting DOACs and at least annually thereafter. 2

Critical Pitfalls to Avoid

• Never use aspirin alone or aspirin plus clopidogrel for stroke prevention in AF - these are inferior to oral anticoagulation and not recommended 2, 3
• Do not withhold anticoagulation based on bleeding risk scores - instead, identify and address modifiable bleeding risk factors (uncontrolled hypertension, alcohol excess, NSAIDs, labile INRs) 1, 2
• Avoid inappropriate DOAC dose reduction - use reduced doses only when meeting specific criteria for each agent (e.g., age, weight, renal function) 2
• Do not discontinue anticoagulation after successful cardioversion or ablation if stroke risk factors persist - base decisions on CHA₂DS₂-VASc score 3
• Never delay emergency cardioversion to achieve therapeutic anticoagulation in hemodynamically unstable patients 2

Monitoring and Reassessment

Reassess stroke and bleeding risks at every patient contact to guide ongoing anticoagulation therapy. 1, 2 For warfarin patients with suboptimal TTR (<65%), consider switching to a DOAC. 3