What are the treatment options for a patient with symptomatic mitral stenosis, particularly those with severe mitral stenosis and potential complications such as atrial fibrillation?

Treatment of Symptomatic Mitral Stenosis

For symptomatic patients with severe mitral stenosis and favorable valve anatomy, percutaneous mitral commissurotomy (PMC) is the first-line intervention, while those with unfavorable anatomy, significant calcification, or more than mild mitral regurgitation should proceed directly to surgical valve replacement. 1

Initial Medical Management

Medical therapy serves as a bridge to intervention or for symptom palliation, but does not prevent disease progression:

• Diuretics should be used for symptom relief when pulmonary congestion or peripheral edema is present 1, 2
• Heart rate control is critical, particularly in patients with atrial fibrillation, as tachycardia shortens diastolic filling time and worsens hemodynamics 3, 2
  • Beta-blockers or calcium channel blockers (verapamil, diltiazem) are first-line agents 3
  • Digoxin is specifically recommended by the European Society of Cardiology for rate control in atrial fibrillation with mitral stenosis 1, 2

Anticoagulation Strategy

All patients with mitral stenosis and atrial fibrillation require anticoagulation with vitamin K antagonists (warfarin), targeting INR 2.0-3.0, regardless of CHA2DS2-VASc score. 4, 5

Additional indications for anticoagulation include:

• History of systemic embolism 3, 2
• Left atrial thrombus on imaging 3
• Dense spontaneous echo contrast in the left atrium 1, 3, 2
• Enlarged left atrium (M-mode diameter >50-60 mm or volume >60 mL/m²) 1, 3, 2

Critical caveat: Direct oral anticoagulants (DOACs) are NOT recommended in moderate-to-severe mitral stenosis due to lack of safety data—only vitamin K antagonists should be used 1, 5

Intervention Decision Algorithm

Step 1: Assess Severity and Symptoms

Severe mitral stenosis is defined as:

• Mitral valve area (MVA) <1.0 cm² 1
• Mean gradient >10 mmHg 1, 3
• Pulmonary artery systolic pressure >50 mmHg 1, 3

Step 2: Evaluate Valve Morphology

PMC is indicated for symptomatic patients (NYHA class II-IV) with:

• Favorable valve anatomy (commissural fusion, minimal calcification, preserved subvalvular apparatus) 1
• No more than mild mitral regurgitation 1
• Absence of left atrial thrombus on transesophageal echocardiography 1, 6

Contraindications to PMC requiring surgical intervention:

• More than mild mitral regurgitation 1
• Severe or bicommissural calcification 3
• Left atrial thrombus (unless it resolves after 1-3 months of anticoagulation) 1
• Absence of commissural fusion (degenerative mitral stenosis) 3, 6
• Severe concomitant valvular disease requiring surgery 3

Step 3: Special Populations

High-risk surgical candidates with calcified valves:

• PMC may be considered as a palliative option even with suboptimal anatomy, though restenosis rates are higher 1, 6
• This provides temporary relief and may delay need for surgery 1, 6

Asymptomatic patients with severe mitral stenosis: PMC should be considered only in highly selected cases with:

• New-onset atrial fibrillation 1
• High thromboembolic risk (history of embolism, dense spontaneous contrast) 1
• Pulmonary artery systolic pressure >50 mmHg at rest or >60 mmHg with exercise 1
• Need for major non-cardiac surgery or pregnancy 1

These interventions should only be performed by experienced operators in comprehensive valve centers. 1

Expected Outcomes

PMC typically achieves:

• Increase in MVA from approximately 1.0 cm² to 1.8 cm² 6
• Reduction in mean gradient from 14-16 mmHg to 6-7 mmHg 1
• Decrease in pulmonary artery pressure 1
• Procedural mortality <1% 6
• Severe mitral regurgitation complication rate 3-10% 6

Prognostic factors affecting PMC success:

• Younger age and less calcified valves have better outcomes 1, 6
• Presence of atrial fibrillation results in lower cardiac output and smaller final valve area (1.6 vs 1.8 cm²), though long-term outcomes remain similar to sinus rhythm 7
• Lower post-procedure mitral regurgitation grade predicts better event-free survival 7

Management of Atrial Fibrillation Complication

Atrial fibrillation worsens hemodynamic tolerance and markedly increases thromboembolic risk in mitral stenosis. 5

• PMC should be performed first in severe symptomatic mitral stenosis with atrial fibrillation, followed by consideration of cardioversion or ablation 5
• PMC does not prevent occurrence of atrial fibrillation but may improve outcomes when combined with rhythm management 5
• Rhythm control versus rate control should be individualized based on symptom severity and left atrial remodeling 5

Common Pitfalls

• Do not delay intervention in symptomatic severe mitral stenosis waiting for "optimal" medical management—medical therapy is palliative only 3, 2
• Do not use DOACs in mitral stenosis patients with atrial fibrillation; only warfarin is appropriate 1, 2
• Do not perform PMC without pre-procedure transesophageal echocardiography to exclude left atrial thrombus 1, 6
• Intervention before development of severe pulmonary hypertension is crucial, as near-systemic pulmonary pressures may result in irreversible right ventricular dysfunction 8