Anticoagulation Choices for Atrial Fibrillation
Direct oral anticoagulants (DOACs)—specifically apixaban, dabigatran, rivaroxaban, or edoxaban—are the first-line anticoagulation choices for patients with atrial fibrillation and no significant bleeding risks or contraindications, preferred over warfarin. 1, 2
Risk Stratification First
Before selecting anticoagulation, calculate the CHA₂DS₂-VASc score to determine stroke risk 1, 3:
- Score 0 (males) or 1 (females, sex alone): No anticoagulation recommended 2, 3
- Score 1 (males) or 2+ (females): Oral anticoagulation strongly recommended 1, 2, 3
The CHA₂DS₂-VASc scoring 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) 3.
First-Line DOAC Selection
For patients requiring anticoagulation, choose one of these four DOACs 1, 2:
Standard Dosing Options
- Apixaban: 5 mg twice daily 1, 2
- Dabigatran: 150 mg twice daily 1, 2
- Rivaroxaban: 20 mg once daily 1, 4
- Edoxaban: 60 mg once daily 1
Why DOACs Over Warfarin
DOACs demonstrate superior or non-inferior efficacy compared to warfarin with significantly lower intracranial hemorrhage risk 2, 5. In pooled analysis of 71,683 patients, standard-dose DOACs reduced stroke/systemic embolism by 19% (HR 0.81), death by 8% (HR 0.92), and intracranial bleeding by 55% (HR 0.45) compared to warfarin 5. The 2020 ACC/AHA guidelines explicitly state that DOACs are recommended over warfarin in DOAC-eligible patients 1.
When Warfarin Is Required Instead
Warfarin remains the only option for 1, 2, 6:
- Moderate-to-severe mitral stenosis
- Mechanical heart valves (target INR 2.5-3.5 depending on valve type)
- End-stage renal disease or dialysis patients
- Severe renal impairment (dabigatran specifically contraindicated with CrCl <30 mL/min)
For warfarin therapy, maintain INR 2.0-3.0 with time in therapeutic range (TTR) ≥65-70% 1, 6. Monitor INR weekly during initiation, then monthly when stable 1, 6.
Dose Adjustments for Special Populations
Renal impairment requires dose reduction 2, 3:
- Apixaban: 2.5 mg twice daily if 2 of 3 criteria present (age ≥80, weight ≤60 kg, creatinine ≥1.5 mg/dL)
- Rivaroxaban: 15 mg daily if CrCl 15-50 mL/min 4
- Edoxaban: 30 mg daily if CrCl 15-50 mL/min 1
- Dabigatran: 75 mg twice daily if CrCl 15-30 mL/min 1
For patients with prior gastrointestinal bleeding, apixaban or dabigatran 110 mg (not available in US) may be preferred due to lower bleeding rates 3.
Critical Pitfalls to Avoid
Never use aspirin or antiplatelet therapy alone for stroke prevention in AF 2. Oral anticoagulation reduces stroke risk by 62%, while aspirin provides only 22% risk reduction 2. The 2018 CHEST guidelines provide a strong recommendation against antiplatelet monotherapy regardless of stroke risk 1, 2.
Do not discontinue anticoagulation after successful cardioversion or ablation if stroke risk factors persist 2, 3. Anticoagulation decisions are based on thromboembolic risk profile (CHA₂DS₂-VASc score), not AF pattern (paroxysmal vs. persistent vs. permanent) 1.
Avoid arbitrary DOAC dose reductions not specified in prescribing information—this leads to inadequate stroke prevention without reducing bleeding risk 2.
Bleeding Risk Assessment
Assess bleeding risk using HAS-BLED score, but high bleeding risk is rarely a contraindication to anticoagulation 2, 3. Instead, address modifiable risk factors: uncontrolled hypertension, labile INRs (if on warfarin), alcohol excess, concomitant NSAIDs/aspirin use 2. A HAS-BLED score ≥3 indicates need for more frequent monitoring and aggressive management of modifiable factors, not avoidance of anticoagulation 2.