What is the recommended anticoagulation (Anticoagulant) therapy for patients with moderate to severe rheumatic mitral stenosis?

Anticoagulation for Moderate to Severe Rheumatic Mitral Stenosis

Vitamin K antagonist (warfarin) with a target INR of 2.0-3.0 is the recommended anticoagulation for all patients with moderate to severe rheumatic mitral stenosis and atrial fibrillation, and should be strongly considered even in sinus rhythm when specific high-risk features are present. 1

Patients with Atrial Fibrillation

Anticoagulation with warfarin (INR 2.0-3.0) is mandatory for all patients with rheumatic mitral stenosis and atrial fibrillation, regardless of stenosis severity. 1, 2

• Direct oral anticoagulants (DOACs) are contraindicated in moderate to severe mitral stenosis—this is one of only two conditions (along with mechanical heart valves) where DOACs should never be used 1
• A recent large randomized trial (n=4531) demonstrated that warfarin led to significantly lower rates of cardiovascular events or mortality compared to rivaroxaban in this population 3
• The target INR is 2.5 (range 2.0-3.0), which is lower than older recommendations that suggested INR 2.5-3.5 1, 2
• Low-intensity anticoagulation (target INR 2.0) has been shown equally effective as moderate-intensity (target INR 3.0) with fewer bleeding complications in a prospective randomized study 4

Patients in Sinus Rhythm (Without Atrial Fibrillation)

Anticoagulation with warfarin (INR 2.0-3.0) is recommended when any of the following high-risk features are present: 1

Class I Indications (Strongest Evidence):

• History of systemic thromboembolism (even a single prior event) 1
• Left atrial thrombus visualized on echocardiography 1

Class IIa Indications (Should Be Considered):

• Thrombus in left atrial appendage on transesophageal echoography 1

Class IIb/IIc Indications (May Be Considered):

• Left atrial diameter ≥55 mm (or ≥50 mm by some guidelines) 1, 5
• Dense spontaneous echo contrast in the left atrium 1, 5
• Significantly dilated left atrium with spontaneous echo contrast 1

Critical Distinction: Mitral Stenosis vs. Mitral Regurgitation

This is fundamentally different from mitral regurgitation, where anticoagulation is NOT indicated in sinus rhythm regardless of severity. 6

• Mitral stenosis carries inherently higher thromboembolic risk due to left atrial stasis and enlargement 1
• The annual stroke risk in mitral stenosis with atrial fibrillation is approximately 4% without anticoagulation 7
• Between 40-75% of patients with rheumatic mitral stenosis will develop atrial fibrillation 7

Practical Anticoagulation Management

Initiation:

• Start warfarin at 2-5 mg daily (lower doses for elderly or those with genetic variations in CYP2C9/VKORC1) 2
• Avoid loading doses—they increase hemorrhagic complications without faster protection 2
• For patients requiring percutaneous mitral balloon commissurotomy (PMBC), ensure at least 4 weeks of effective anticoagulation before the procedure 1
• Perform transesophageal echocardiography immediately before PMBC to exclude left atrial thrombus 1

Monitoring:

• Check INR weekly during initiation, then monthly once stable in therapeutic range 1, 2
• Reassess renal and hepatic function at least annually 1
• Most patients are maintained on 2-10 mg daily 2

Target INR:

• Standard target: INR 2.5 (range 2.0-3.0) 1, 2, 4
• If recurrent systemic embolism occurs despite adequate anticoagulation, consider intensifying to INR 3.0 (range 2.5-3.5) or adding aspirin 80-100 mg daily 5

Common Pitfalls to Avoid

Do not use DOACs in moderate to severe mitral stenosis—despite observational data suggesting potential benefit 8, the only adequately powered randomized trial showed worse outcomes with rivaroxaban compared to warfarin 3

Do not withhold anticoagulation in sinus rhythm patients with high-risk features—the embolic risk does not correlate well with stenosis severity alone but rather with left atrial size and stasis 5

Do not attempt cardioversion before intervention in severe mitral stenosis—sinus rhythm will not be maintained unless the obstruction is relieved 1

Do not assume adequate anticoagulation based on prescription alone—less than 80% of eligible patients actually take anticoagulation, and less than 30% maintain therapeutic INR 7

Special Populations

After Valve Replacement:

• Mechanical mitral valve: Warfarin with target INR 3.0 (range 2.5-3.5) plus aspirin 75-100 mg daily indefinitely 2
• Bioprosthetic mitral valve: Warfarin with target INR 2.5 (range 2.0-3.0) for first 3 months, then aspirin alone if no atrial fibrillation 6, 2

Pregnancy Considerations:

• Consider bioprosthetic valve rather than mechanical for women of childbearing age to avoid hazards of anticoagulation during pregnancy 1