From the Guidelines
For patients with non-rheumatic moderate mitral stenosis and atrial fibrillation, long-term oral anticoagulation with a vitamin K antagonist (warfarin) is recommended, with a target INR of 2.0-3.0, as stated in the 2021 update to the 2016 ACC/AHA clinical performance and quality measures for adults with atrial fibrillation or atrial flutter 1. The presence of mitral stenosis creates abnormal blood flow patterns in the left atrium, which, when combined with the stasis from atrial fibrillation, substantially increases the risk of thrombus formation and subsequent stroke or systemic embolism. Direct oral anticoagulants (DOACs) are not recommended for these patients due to the exclusion criteria defined as moderate or severe mitral stenosis or a mechanical heart valve, as mentioned in the same update 1. Regular INR monitoring is essential for patients on warfarin, typically every 1-4 weeks depending on stability, as recommended in the guidelines 1. Bridging with low molecular weight heparin or unfractionated heparin may be necessary during initiation of therapy or if procedures require temporary warfarin discontinuation. Patients should also be educated about potential drug-food interactions with warfarin and the importance of consistent vitamin K intake through diet. The anticoagulation should be continued indefinitely, regardless of the CHA₂DS₂-VASc score, as the mitral stenosis itself significantly increases the risk of thromboembolism. Key considerations in managing these patients include:
- The risk of thromboembolism, irrespective of whether the AF pattern is paroxysmal, persistent, or permanent 1
- Individualization of anticoagulant therapy based on shared decision-making after discussion of the absolute risks and relative risks of stroke and bleeding, as well as the patient’s values and preferences 1
- Reevaluation of the need for and choice of anticoagulant therapy at periodic intervals to reassess stroke and bleeding risks 1
From the FDA Drug Label
For patients with AF and mitral stenosis, anticoagulation with oral warfarin is recommended (7th ACCP) A moderate dose regimen (INR 2.0 to 3.0) is recommended for these patients.
The recommended anticoagulation regimen for a patient with non-rheumatic moderate mitral stenosis and atrial fibrillation (AF) is oral warfarin with a target INR of 2.0-3.0 2.
- Key points:
- Anticoagulation with oral warfarin is recommended for patients with AF and mitral stenosis.
- The target INR for these patients is 2.0-3.0.
From the Research
Anticoagulation Regimen for Non-Rheumatic Moderate Mitral Stenosis and Atrial Fibrillation
The recommended anticoagulation regimen for a patient with non-rheumatic moderate mitral stenosis and atrial fibrillation (AF) is based on several studies.
- A study published in 2003 3 found that low intensity anticoagulation (target INR = 2) is effective and safe in high-risk patients with mitral stenosis and AF.
- Another study published in 2006 4 found that combined therapy with anticoagulant and antiplatelet therapy reduced the risk of vascular events by 58.3% in patients with mitral stenosis and AF.
- A study published in 2010 5 compared the effectiveness of Aspirin vs Warfarin in preventing thromboembolism in patients with AF and mitral valvulopathy, and found that Warfarin was more effective in preventing embolic events.
Alternative Anticoagulants
- A study published in 2012 6 found that Dabigatran, an oral anticoagulant that inhibits thrombin, is an alternative to Warfarin for patients with AF and a moderate or high risk of thrombosis, without associated valvular abnormalities.
- Another study published in 2012 7 found that Rivaroxaban, a factor Xa inhibitor, is not sufficiently convincing to challenge the standard use of Warfarin for patients with AF and a major risk of thrombosis.
Key Findings
- Low intensity anticoagulation (target INR = 2) is effective and safe in high-risk patients with mitral stenosis and AF 3.
- Combined therapy with anticoagulant and antiplatelet therapy reduces the risk of vascular events in patients with mitral stenosis and AF 4.
- Warfarin is more effective than Aspirin in preventing embolic events in patients with AF and mitral valvulopathy 5.
- Dabigatran is an alternative to Warfarin for patients with AF and a moderate or high risk of thrombosis, without associated valvular abnormalities 6.