What is the management for severe mitral stenosis?

Management of Severe Mitral Stenosis

Percutaneous mitral balloon commissurotomy (PMBC) is the first-line treatment for symptomatic severe rheumatic mitral stenosis with favorable valve anatomy; surgical mitral valve replacement is reserved for patients with unfavorable anatomy or failed PMBC. 1, 2

Initial Assessment and Etiology Determination

The critical first step is distinguishing rheumatic mitral stenosis (RMS) from degenerative mitral stenosis (DMS), as interventions differ fundamentally between these etiologies 3:

• Rheumatic MS: Characterized by commissural fusion, amenable to PMBC
• Degenerative MS: Lacks commissural fusion (due to mitral annular calcification), making PMBC ineffective 3, 4

Medical Management (Palliative Only)

Medical therapy provides symptom relief but does not prevent disease progression 1:

Symptom Control

• Diuretics for pulmonary congestion or peripheral edema 1, 2
• Beta-blockers or rate-limiting calcium channel blockers for heart rate control, particularly crucial in atrial fibrillation to prolong diastolic filling time 1, 2
• Digoxin specifically for heart rate control in patients with atrial fibrillation 1, 2

Anticoagulation (Mandatory in Specific Situations)

Use vitamin K antagonists (target INR 2-3), NOT NOACs 1, 5:

• History of systemic embolism 1, 2
• Atrial fibrillation (paroxysmal or permanent) 5, 2
• Dense spontaneous contrast in left atrium on echocardiography 1, 2
• Enlarged left atrium (M-mode diameter >60 mL/m²) 1, 2

Intervention Indications

Symptomatic Patients (NYHA Class II-IV)

PMBC is indicated for all symptomatic patients with severe MS (valve area ≤1.5 cm²) and favorable valve morphology 1, 2:

• Minimal valve calcification
• No significant mitral regurgitation (≤2/4 grade) 6
• Minimal subvalvular thickening 7

Asymptomatic Patients (Intervention Indicated If ANY of the Following)

• Pulmonary artery systolic pressure >50 mmHg 1, 2
• New-onset atrial fibrillation 1, 2
• High thromboembolic risk (history of embolism or dense spontaneous contrast) 1, 2

Intervention Selection Algorithm

For Rheumatic Mitral Stenosis

Step 1: Assess Valve Morphology Favorable anatomy includes 7, 6:

• Minimal leaflet calcification (especially at commissures)
• Preserved leaflet mobility
• Minimal subvalvular thickening and fusion

Step 2: Choose Intervention Based on Anatomy

Favorable anatomy:

• First choice: PMBC 1, 2, 7
• Success rate depends on valve anatomy, patient characteristics, and operator expertise 7
• Immediate results predicted by mitral valve area, subvalvular thickening, and commissural calcification 7

Unfavorable anatomy:

• Open mitral commissurotomy if valve anatomy allows and patient is surgical candidate 2, 8
• Mitral valve replacement for heavy calcification or significant subvalvular fusion 2
• PMBC may still be attempted in high-risk surgical patients even with suboptimal anatomy 7, 9

For Degenerative Mitral Stenosis

Medical management is primary therapy 4:

• PMBC has no role due to absence of commissural fusion 3, 4
• Surgical mitral valve replacement only when symptoms are severely limiting despite medical therapy 4
• These patients are typically elderly with multiple comorbidities and high surgical risk 4

Special Populations

Pregnancy

• PMBC can be performed relatively safely in symptomatic patients (NYHA III-IV) despite medical therapy 3
• Mitral valve surgery carries significant risk to mother and fetus, reserved only when mother's life is at risk 3
• Diuresis must be cautious to minimize placental hypoperfusion 3

Left Atrial Thrombus

• Absolute contraindication to PMBC 6
• Requires transesophageal echocardiography for exclusion before procedure 6

Monitoring After Intervention

Post-PMBC parameters determining long-term outcomes 7:

• Mitral valve area achieved
• Residual mitral regurgitation severity
• Mean transmitral gradient
• Pulmonary artery pressure

Follow-up for asymptomatic severe MS not yet intervened upon:

• Every 2-3 years per European Society of Cardiology 1, 2
• Every 3-5 years per American College of Cardiology/American Heart Association 1

Critical Pitfalls to Avoid

• Never use NOACs in mitral stenosis patients with atrial fibrillation—only vitamin K antagonists are appropriate 1, 5
• Do not delay anticoagulation in patients with enlarged left atrium or dense spontaneous contrast, even without atrial fibrillation 5
• Do not assume medical therapy prevents progression—it is purely palliative; regular monitoring for intervention indications is essential 1, 5
• Do not attempt PMBC in degenerative mitral stenosis—it will fail and may cause harm 3, 5
• Severe mitral regurgitation (≥2/4 grade) is the most common immediate complication of PMBC 7
• Pressure half-time method for valve area assessment is invalid immediately after PMBC 6