From the Guidelines
The main difference between valvular and non-valvular atrial fibrillation lies in the underlying heart valve condition, with valvular AF associated with moderate to severe mitral stenosis or mechanical heart valves, and non-valvular AF occurring in the absence of these specific valve problems. This distinction is crucial for treatment decisions, particularly anticoagulation therapy. Patients with valvular AF require vitamin K antagonists like warfarin for stroke prevention, as direct oral anticoagulants (DOACs) are contraindicated in these cases 1. In contrast, patients with non-valvular AF can be treated with either warfarin or DOACs such as apixaban, rivaroxaban, dabigatran, or edoxaban 2, 3. The distinction exists because patients with mechanical valves or significant mitral stenosis were excluded from the major clinical trials that established the efficacy and safety of DOACs, and limited evidence suggests DOACs may be less effective in these specific valve conditions.
Key Differences in Treatment
- Valvular AF: warfarin is recommended for stroke prevention
- Non-valvular AF: warfarin or DOACs (apixaban, rivaroxaban, dabigatran, or edoxaban) can be used for stroke prevention
- The choice of anticoagulant depends on the underlying valve pathology and the patient's individual risk factors for stroke and bleeding
Importance of Accurate Diagnosis
Accurate diagnosis of valvular or non-valvular AF is essential to determine the appropriate anticoagulation strategy and minimize the risk of stroke and bleeding complications. The CHA2DS2-VASc score can be used to assess the risk of stroke in patients with non-valvular AF, and the HAS-BLED score can be used to assess the risk of bleeding 2.
Recent Guidelines and Recommendations
Recent guidelines recommend the use of DOACs over warfarin for stroke prevention in patients with non-valvular AF, due to their improved safety and efficacy profile 2, 1. However, warfarin remains the recommended anticoagulant for patients with valvular AF, due to the lack of evidence supporting the use of DOACs in these patients.
From the FDA Drug Label
Atrial Fibrillation Five recent clinical trials evaluated the effects of warfarin in patients with non-valvular atrial fibrillation (AF). ... There are no adequate and well-controlled studies in populations with atrial fibrillation and valvular heart disease. For patients with AF and mitral stenosis, anticoagulation with oral warfarin is recommended (7th ACCP) For patients with AF and prosthetic heart valves, anticoagulation with oral warfarin should be used; the target INR may be increased and aspirin added depending on valve type and position, and on patient factors.
The main difference between valvular and non-valvular atrial fibrillation (AFib) is the presence of valvular heart disease, such as mitral stenosis or prosthetic heart valves, in valvular AFib.
- Valvular AFib involves heart valves and may require different anticoagulation management, such as increased target INR and addition of aspirin.
- Non-valvular AFib does not involve valvular heart disease and has been studied in clinical trials, with recommended anticoagulation therapy with warfarin to reduce thromboembolic events, including stroke 4.
From the Research
Definition and Classification
- The term "valvular atrial fibrillation (AF)" refers to patients with mitral stenosis or artificial heart valves, and is associated with a higher risk of thromboembolic events 5.
- Non-valvular AF, on the other hand, refers to patients without these specific valve conditions, but may still have other types of valvular heart disease 5.
- The European Heart Rhythm Association (EHRA) proposes a functional classification system, categorizing valvular heart disease into two types: EHRA Type 1 VHD, which requires therapy with a Vitamin K antagonist (VKA), and EHRA Type 2 VHD, which requires therapy with a VKA or a Non-VKA oral anticoagulant (NOAC) 6.
Risk of Thromboembolic Events
- Patients with valvular AF have a higher risk of thromboembolic events compared to those with non-valvular AF, with a hazard ratio of 1.39 (95% CI 1.14-1.69, P = 0.001) 7.
- The CHA2DS2VASc score is a clinical risk stratification tool that estimates the risk of stroke and thromboembolism in non-valvular AF, and is also useful in patients with valvular heart disease 7, 6.
- Factors independently associated with increased risk of stroke/thromboembolic events include older age, higher CHA2DS2VASc score, and presence of valvular heart disease 7, 8.
Management and Treatment
- Antithrombotic therapy is more commonly prescribed in patients with valvular AF compared to non-valvular AF, with 71% of patients with CHA2DS2VASc > 2 receiving antithrombotic therapy 8.
- The choice of anticoagulant therapy, including vitamin K antagonists (VKAs) and non-vitamin K antagonist oral anticoagulants (NOACs), depends on the type of valvular heart disease and the patient's individual risk factors 6, 9.
- Patients with non-valvular AF and heart failure may benefit from direct oral anticoagulants (DOACs), which have been shown to be at least as efficacious and safe as warfarin in this population 9.