Apixaban for Stroke Reduction in Atrial Fibrillation
Apixaban 5 mg twice daily is recommended as first-line therapy over warfarin for stroke prevention in patients with nonvalvular atrial fibrillation, as it provides superior stroke reduction, lower mortality, and significantly less major bleeding. 1
Standard Dosing
Standard dose: 5 mg orally twice daily for most patients with nonvalvular AF 2
Reduced dose: 2.5 mg twice daily is required when patients have at least 2 of the following characteristics: 2
- Age ≥80 years
- Body weight ≤60 kg
- Serum creatinine ≥1.5 mg/dL
Evidence Supporting Apixaban Over Warfarin
The ARISTOTLE trial demonstrated apixaban's superiority across multiple critical outcomes: 1
- 21% reduction in stroke or systemic embolism (1.27% vs 1.60% per year with warfarin, P=0.01) 3
- 11% reduction in all-cause mortality (P=0.047) 3
- 31% reduction in major bleeding (P<0.001) compared to warfarin 3
- 51% reduction in hemorrhagic stroke when combined with other DOAC trials 1
The American Heart Association/American Stroke Association gives apixaban a Class I, Level of Evidence B recommendation, explicitly stating it should be used "in preference to warfarin" for stroke reduction 1
Critical Contraindications
Apixaban is absolutely contraindicated in: 1, 4
- Moderate to severe mitral stenosis
- Mechanical heart valves
These patients must use warfarin, as DOACs have not been studied and may be harmful in these populations 1
Special Populations
End-stage renal disease/dialysis (CrCl <15 mL/min): 1, 4
- Warfarin or dose-adjusted apixaban may be reasonable options
- This is the only DOAC with any data supporting use in dialysis patients
Renal function monitoring: 4
- Assess creatinine clearance before initiation
- Reassess at least annually
Timing After Acute Stroke
For patients with AF who have had an acute ischemic stroke, timing of anticoagulation initiation depends on hemorrhagic transformation risk: 1
- TIA patients: Initiate anticoagulation immediately (Class IIa recommendation) 1
- Low hemorrhagic risk stroke: May initiate 2-14 days after stroke 1
- High hemorrhagic risk stroke (large infarcts): Delay initiation beyond 14 days to reduce intracranial hemorrhage risk 1
Switching Between Anticoagulants
From warfarin to apixaban: 2
- Discontinue warfarin
- Start apixaban when INR <2.0
From apixaban to warfarin: 2
- Discontinue apixaban
- Begin parenteral anticoagulant plus warfarin at time of next apixaban dose
- Continue parenteral agent until INR therapeutic
Perioperative Management
Discontinue apixaban: 2
- 48 hours before procedures with moderate-to-high bleeding risk
- 24 hours before procedures with low bleeding risk
- Bridging anticoagulation is not generally required 2
Advantages Over Warfarin in Clinical Practice
Apixaban offers practical benefits: 1, 4
- No routine INR monitoring required (unlike warfarin's weekly-to-monthly monitoring) 4
- No dietary restrictions
- Fewer drug interactions
- Predictable pharmacokinetics
- Lower discontinuation rates than warfarin 3
Common Pitfall to Avoid
The most critical error is premature discontinuation without bridging to another anticoagulant, which dramatically increases thrombotic stroke risk 2. If apixaban must be stopped for reasons other than bleeding or completion of therapy, immediately transition to alternative anticoagulation 2