Treatment Options for Valvular vs Non-Valvular Atrial Fibrillation
For valvular AF (moderate-to-severe mitral stenosis or mechanical heart valves), warfarin is the only recommended anticoagulant with a target INR of 2.0-3.0, while for non-valvular AF, direct oral anticoagulants (DOACs) are preferred over warfarin due to similar or better efficacy with lower intracranial bleeding risk. 1, 2
Defining Valvular vs Non-Valvular AF
The distinction is critical because it determines anticoagulant choice:
- Valvular AF is defined as AF occurring with moderate-to-severe mitral stenosis or mechanical heart valves 2
- Non-valvular AF includes all other AF patients, even those with other types of valvular disease (mild mitral stenosis, aortic stenosis, mitral regurgitation, etc.) 2
- Valvular AF increases stroke risk 20-fold compared to sinus rhythm, while non-valvular AF increases risk 5-fold 2
Treatment for Valvular AF
Warfarin is mandatory and DOACs are contraindicated:
- Warfarin with target INR 2.0-3.0 is the only recommended anticoagulant for patients with mechanical heart valves 1, 3
- For mechanical valves, the target INR may be higher (2.5-3.5) depending on valve type and position: bileaflet valves in the aortic position require INR 2.0-3.0, while tilting disk or bileaflet valves in the mitral position require INR 2.5-3.5 3
- Dabigatran is specifically contraindicated (Class III: Harm) in patients with mechanical heart valves due to increased thromboembolic events 1, 2
- For rheumatic mitral stenosis with AF, warfarin (INR 2.0-3.0) is the only recommended anticoagulant 1, 3
INR Monitoring Requirements
- INR should be measured at least weekly during warfarin initiation 1
- Once stable, INR monitoring should occur at least monthly 1, 4
Treatment for Non-Valvular AF
Risk stratification using CHA₂DS₂-VASc score determines treatment intensity:
CHA₂DS₂-VASc Score Components 1, 2
- High-risk factors (2 points each): Prior stroke/TIA/systemic embolism, Age ≥75 years
- Moderate-risk factors (1 point each): Age 65-74 years, Hypertension, Diabetes, Heart failure/LV dysfunction (EF ≤35%), Vascular disease, Female sex
Treatment Algorithm Based on Risk Score
CHA₂DS₂-VASc Score ≥2 (High Risk):
- Oral anticoagulation is recommended 1
- DOACs are preferred over warfarin (apixaban, dabigatran, rivaroxaban) due to similar or better efficacy with lower intracranial bleeding risk 2
- If DOACs are used, warfarin (INR 2.0-3.0) is an acceptable alternative 1
CHA₂DS₂-VASc Score = 1 (Intermediate Risk):
- No antithrombotic therapy, oral anticoagulation, or aspirin may be considered 1
- The decision should be individualized based on bleeding risk and patient preference 1
CHA₂DS₂-VASc Score = 0 (Low Risk):
- It is reasonable to omit antithrombotic therapy 1
Special Populations in Non-Valvular AF
End-Stage Chronic Kidney Disease (CrCl <15 mL/min) or Hemodialysis:
- Warfarin (INR 2.0-3.0) is preferred over DOACs 1, 2
- DOACs (dabigatran and rivaroxaban) are not recommended due to lack of clinical trial evidence in this population 1
Moderate-to-Severe CKD (not on dialysis):
- Reduced doses of DOACs may be considered based on creatinine clearance 1
- Dose adjustments are available for apixaban, dabigatran, and rivaroxaban 1
Common Pitfalls to Avoid
- Misclassifying valvular status: Using DOACs in patients with moderate-to-severe mitral stenosis or mechanical valves can lead to catastrophic thromboembolic events 2
- Assuming all valvular disease is "valvular AF": Only moderate-to-severe mitral stenosis and mechanical valves qualify; patients with mild mitral stenosis, aortic stenosis, or mitral regurgitation are classified as non-valvular AF and can receive DOACs 2
- Using low-dose warfarin (INR <1.6): This leads to more thromboembolic events without reducing major bleeding compared to adjusted-dose warfarin (INR 2.0-3.0) 5
- Inadequate INR monitoring: Failure to monitor weekly during initiation or monthly when stable increases both thrombotic and bleeding complications 1