Warfarin is NOT routinely indicated for native aortic stenosis alone
For patients with aortic stenosis who do not have atrial fibrillation or another indication for anticoagulation, antiplatelet therapy (not warfarin) is recommended. 1
When Warfarin IS Indicated in Aortic Stenosis Patients
Warfarin becomes necessary only when specific additional conditions coexist with aortic stenosis:
1. Atrial Fibrillation
- If a patient with aortic stenosis develops AF, warfarin is indicated based on standard AF stroke risk stratification (CHA₂DS₂-VASc score ≥2)
- Target INR: 2.0-3.0 2, 3
- Important caveat: Direct oral anticoagulants (DOACs) are NOT contraindicated in native aortic stenosis with AF, unlike in moderate-to-severe mitral stenosis 1, 4
2. After Mechanical Aortic Valve Replacement
If the aortic stenosis is treated surgically with a mechanical valve:
- Bileaflet or current-generation single-tilting-disk valves WITHOUT risk factors: Warfarin target INR 2.5 (range 2.0-3.0) plus low-dose aspirin (75-100 mg/day) 2, 3
- WITH risk factors (AF, prior thromboembolism, LV dysfunction, hypercoagulable state): Warfarin target INR 3.0 (range 2.5-3.5) plus low-dose aspirin 2
- Caged ball or caged disk valves: Always INR 3.0 (range 2.5-3.5) plus aspirin 5, 3
3. After Bioprosthetic Aortic Valve Replacement
First 3 months post-surgery: Warfarin INR 2.0-3.0 is reasonable for all patients 1, 2, 6
After 3 months: Switch to aspirin 75-100 mg daily alone UNLESS the patient has:
- Atrial fibrillation
- Prior thromboembolism
- LV dysfunction
- Hypercoagulable condition
4. History of Stroke/TIA Before Valve Surgery
- Patients with prior ischemic stroke or TIA who undergo valve replacement should continue antiplatelet therapy after bioprosthetic valve insertion (no anticoagulation needed beyond 3-6 months) 1
Key Clinical Pitfalls
Common mistake: Initiating warfarin for native aortic stenosis without another indication. This provides no benefit and increases bleeding risk 1. The evidence shows no conclusive association between native aortic valve disease alone and increased stroke risk requiring anticoagulation 1.
DOACs in aortic stenosis: Unlike mitral stenosis, DOACs are NOT contraindicated in patients with aortic stenosis and AF. Recent data suggest DOACs may actually be more effective than warfarin for stroke prevention in this population 8.
Post-TAVR anticoagulation: Current practice favors dual antiplatelet therapy (aspirin plus clopidogrel) for 3-6 months, then aspirin alone, rather than routine warfarin 6. Warfarin is only used if there's a separate indication (like AF).