Valvular vs Non-Valvular Atrial Fibrillation: Treatment Differences
The fundamental distinction between valvular and non-valvular AF determines anticoagulation choice: valvular AF (moderate-to-severe mitral stenosis or mechanical heart valves) mandates warfarin exclusively, while non-valvular AF allows direct oral anticoagulants (DOACs) as preferred first-line therapy. 1, 2
Defining the Categories
Valvular AF is specifically defined as AF occurring with:
- Moderate-to-severe mitral stenosis (potentially requiring surgical intervention), OR
- Mechanical prosthetic heart valves 1, 2
Non-valvular AF includes all other AF patients, even those with:
- Mild mitral stenosis
- Mitral or aortic regurgitation
- Aortic stenosis
- Bioprosthetic valves
- Prior valve repair or valvuloplasty 1
This distinction matters because valvular AF increases stroke risk 20-fold compared to sinus rhythm, while non-valvular AF increases risk only 5-fold. 2
Anticoagulation for Valvular AF
Mechanical Heart Valves
Warfarin is the only acceptable anticoagulant—DOACs are absolutely contraindicated (Class III: Harm). 1, 3
Target INR depends on valve type and position:
- Bileaflet valve in aortic position without additional risk factors: INR 2.5 (range 2.0-3.0) 3, 4
- Tilting disk valves, bileaflet valves in mitral position, or bileaflet aortic valves with additional risk factors: INR 3.0 (range 2.5-3.5) 3, 4
- Older caged ball or caged disk valves: INR 3.0 (range 2.5-3.5) plus aspirin 75-100 mg daily 4, 5
INR monitoring requires weekly checks during initiation, then monthly once stable. 1, 3
Rheumatic Mitral Stenosis
Warfarin with target INR 2.0-3.0 is mandatory regardless of CHA₂DS₂-VASc score, as this represents the highest-risk AF subgroup for thromboembolism. 1, 4
Anticoagulation for Non-Valvular AF
Risk Stratification
Use CHA₂DS₂-VASc score to determine anticoagulation need:
- Score ≥2 in men or ≥3 in women: Oral anticoagulation mandatory 1, 6
- Score 1: Anticoagulation reasonable, individualize based on bleeding risk 6
- Score 0: Anticoagulation may be omitted 6
The score includes: congestive heart failure (1 point), hypertension (1), age ≥75 years (2), diabetes (1), prior stroke/TIA/thromboembolism (2), vascular disease (1), age 65-74 years (1), female sex (1). 1, 6
Anticoagulant Selection
DOACs are preferred over warfarin for non-valvular AF due to superior safety profiles (particularly lower intracranial bleeding) with equivalent or better efficacy. 6, 2, 7
DOAC options with normal renal function:
- Apixaban 5 mg twice daily 6
- Dabigatran 150 mg twice daily 6
- Rivaroxaban 20 mg once daily with evening meal 6
- Edoxaban (dose varies by renal function) 1
Warfarin remains preferred for:
- End-stage chronic kidney disease or hemodialysis (target INR 2.0-3.0) 6, 2
- Patients unable to afford DOACs 4
DOACs reduce stroke and systemic embolism by 60-80% compared to placebo, similar to warfarin's efficacy. 7
Aspirin Monotherapy
Aspirin is substantially less effective than anticoagulation and is not recommended for stroke prevention in AF. 7 It may only be considered in patients with absolute contraindications to all anticoagulants. 1
Critical Pitfalls to Avoid
Never use DOACs in patients with mechanical heart valves—this is an absolute contraindication that increases thromboembolic events. 1, 3
Do not misclassify valvular status: Patients with bioprosthetic valves, mild mitral stenosis, or other non-stenotic valve disease are considered non-valvular AF and can receive DOACs. 1, 2
Do not use CHA₂DS₂-VASc scoring for mechanical valve patients—the valve itself mandates anticoagulation regardless of score. 3
Avoid DOACs in end-stage renal disease or dialysis—insufficient evidence exists for safety and efficacy in this population. 6, 2
Do not target the lower boundary of INR range in mechanical valve patients—aim for the specific target INR value (2.5 or 3.0) to avoid thromboembolic complications. 3
Monitoring Requirements
For warfarin therapy:
- Weekly INR checks during initiation 1, 6
- Monthly INR checks once stable (consistently therapeutic) 1, 3
- Target INR 2.0-3.0 for non-valvular AF and most mechanical valves 1, 4
For DOAC therapy:
For all AF patients: