What is the recommended anticoagulation therapy for patients with atrial fibrillation (AFib) and mitral stenosis?

Anticoagulation in Atrial Fibrillation with Mitral Stenosis

For patients with atrial fibrillation and mitral stenosis, warfarin is the only recommended anticoagulant with a target INR of 2.0-3.0; direct oral anticoagulants (DOACs) are contraindicated in this population. 1, 2

Why Warfarin is Mandatory

• Mitral stenosis is an absolute exclusion criterion for DOACs (dabigatran, rivaroxaban, apixaban, edoxaban), as these agents have not been studied in this population and are specifically contraindicated when moderate-to-severe mitral stenosis is present. 1, 2

• The American College of Chest Physicians explicitly recommends adjusted-dose vitamin K antagonist therapy (target INR 2.0-3.0) rather than no therapy, aspirin alone, or combination aspirin-clopidogrel for AF patients with mitral stenosis. 1

• The FDA labeling for warfarin specifically addresses AF with mitral stenosis, recommending anticoagulation with oral warfarin for these patients. 3

Target INR and Monitoring

• Maintain INR between 2.0-3.0 for patients with AF and mitral stenosis. 1, 3

• Some older guidelines suggested a higher target INR of 2.5-3.5 for rheumatic mitral stenosis, but contemporary evidence supports that a target INR of 2.0 is equally effective with less bleeding risk. 1, 4

• Check INR at least weekly during warfarin initiation and monthly once stable in the therapeutic range. 1

Evidence Supporting Lower Intensity Anticoagulation

• A randomized trial of 103 patients with mitral stenosis and AF compared low-intensity (target INR 2.0) versus moderate-intensity (target INR 3.0) anticoagulation over 4.5 years. The low-intensity group had similar thromboembolic protection (0.41 vs 0.40 events per 100 patient-years) with numerically fewer major bleeding events (1.25 vs 2.0 per 100 patient-years). 4

• This supports using the lower end of the therapeutic range (INR 2.0-3.0) rather than higher intensity regimens. 4

Critical Pitfalls to Avoid

• Never use DOACs in patients with mitral stenosis, even if the stenosis is mild—this is an absolute contraindication based on lack of safety and efficacy data. 1, 2

• Do not substitute aspirin alone or aspirin-clopidogrel combination for warfarin in these high-risk patients, as anticoagulation is vastly superior for stroke prevention. 1

• Do not underdose warfarin due to bleeding concerns—patients with mitral stenosis and AF have stroke rates of approximately 4% per year without adequate anticoagulation. 5

• Be aware that in real-world practice, less than 80% of eligible patients receive anticoagulation and less than 30% maintain therapeutic INR, highlighting the need for close monitoring. 5

When Warfarin is Contraindicated

• If the patient is unsuitable for or refuses warfarin therapy (for reasons other than bleeding concerns), the American College of Chest Physicians recommends combination therapy with aspirin and clopidogrel rather than aspirin alone, though this is substantially inferior to warfarin. 1

Special Considerations

• Rheumatic mitral stenosis carries particularly high stroke risk, with 40-75% of patients developing AF and a 4% annual stroke rate. 5

• The risk of thromboembolism is independent of whether the AF is paroxysmal, persistent, or permanent—all patterns require the same anticoagulation approach. 1

• Patients with mitral stenosis who undergo valve replacement with a bioprosthetic valve may eventually become candidates for DOACs, but this remains under investigation and warfarin remains standard. 5