Prevention Strategy for Severe Mitral Stenosis and Stroke
For a patient with severe mitral stenosis and a history of stroke, warfarin anticoagulation with a target INR of 2.5 (range 2.0-3.0) is the mandatory treatment, regardless of whether atrial fibrillation is present. 1, 2
Primary Anticoagulation Strategy
Warfarin is the only recommended anticoagulant for moderate to severe mitral stenosis. The 2021 AHA/ASA guidelines explicitly state that in patients with valvular AF (defined as moderate to severe mitral stenosis or any mechanical heart valve), warfarin is recommended to reduce the risk of recurrent stroke or TIA. 1
Target INR and Monitoring
- Target INR should be 2.5 with a therapeutic range of 2.0-3.0 for all patients with severe mitral stenosis and prior stroke. 1, 2, 3
- INR should be checked weekly during initiation and monthly once stable in the therapeutic range. 2, 4
- The goal is to maintain time in therapeutic range (TTR) >65% to ensure optimal stroke protection. 4
Warfarin Initiation
- Start warfarin at 2-5 mg daily and avoid loading doses to minimize hemorrhagic complications. 2, 3
- Adjust dosing based on INR results rather than using fixed high-dose regimens. 3
Critical Contraindications
Direct oral anticoagulants (DOACs) are absolutely contraindicated in moderate to severe mitral stenosis. 2 The 2021 AHA/ASA guidelines give dabigatran a Class 3: Harm recommendation in patients with mechanical heart valves, and DOACs have been excluded from all major trials in moderate to severe mitral stenosis. 1
While one observational Korean study suggested potential benefit of DOACs in mitral stenosis 5, this directly contradicts guideline recommendations and represents off-label use that should not guide clinical practice until randomized trial data are available. 6
Role of Antiplatelet Therapy
Antiplatelet therapy alone is insufficient for stroke prevention in severe mitral stenosis. 1 However, there is evidence supporting combination therapy:
- Adding aspirin 75-100 mg daily to warfarin may be considered in patients with prior embolism who remain at very high risk. 7
- One randomized trial showed that combined antiplatelet plus warfarin therapy reduced vascular events by 58.3% compared to warfarin alone in mitral stenosis patients. 7
- The AHA/ASA guidelines note that antiplatelet agents should not be routinely added to warfarin in rheumatic heart disease to avoid additional bleeding risk, but this may be reasonable in select high-risk cases. 4
Atrial Fibrillation Considerations
If atrial fibrillation is present (which occurs in 40-75% of mitral stenosis patients), warfarin anticoagulation is absolutely mandatory. 1, 2, 6
- The presence of AF increases stroke risk to 4% per year in mitral stenosis patients. 6
- The same INR target of 2.0-3.0 applies whether AF is present or absent. 2
High-Risk Features Requiring Anticoagulation Even in Sinus Rhythm
Even without atrial fibrillation, warfarin should be strongly considered when any of these features are present: 2
- History of systemic thromboembolism (as in this patient with prior stroke)
- Left atrial thrombus on echocardiography
- Left atrial diameter ≥55 mm
- Dense spontaneous echo contrast in the left atrium
Pre-Procedural Evaluation
If percutaneous mitral balloon commissurotomy (PMBC) is being considered, perform transesophageal echocardiography immediately before the procedure to exclude left atrial thrombus. 2
Common Pitfalls to Avoid
- Never switch to a DOAC thinking it will be more convenient—this increases stroke risk substantially. 2
- Do not use antiplatelet therapy alone as primary prevention—warfarin is essential. 1
- Avoid subtherapeutic INR levels (< 2.0), which significantly increase thromboembolism risk. 4
- Do not allow INR to exceed 3.5 routinely, as intracranial hemorrhage risk rises significantly above this level. 4
- One study showed that patients with prior embolism had a 6.6% annual event rate with warfarin alone at INR 2.0-3.0, suggesting this population may need intensified therapy. 7