What are the treatment options for a patient with symptomatic mitral stenosis, possibly with atrial fibrillation and significant valve narrowing?

Treatment of Symptomatic Mitral Stenosis

For symptomatic patients with moderate to severe mitral stenosis (valve area <1.5 cm²) and favorable valve morphology, percutaneous mitral commissurotomy (PMC) is the treatment of choice and should be performed urgently to prevent irreversible pulmonary hypertension, right heart failure, and death. 1, 2

Initial Assessment and Risk Stratification

Before determining the intervention approach, you must:

• Obtain transthoracic echocardiography immediately to measure mitral valve area (planimetry is the reference standard), mean gradient, pulmonary artery systolic pressure, and assess valve morphology for PMC suitability 1, 3
• Perform transesophageal echocardiography to exclude left atrial thrombus before any intervention, as this is an absolute contraindication to PMC 1, 4
• Assess NYHA functional class as this drives intervention timing—NYHA class II-IV symptoms mandate intervention 1, 3, 2
• Evaluate valve morphology using scoring systems to determine PMC candidacy: favorable anatomy includes commissural fusion with balanced chordal attachments, while unfavorable features include parachute mitral valve, supramitral rings, severe calcification, or small mitral annulus 1

Treatment Algorithm Based on Valve Morphology

Favorable Valve Anatomy (Most Patients)

PMC is the Class I indication for: 1

• All symptomatic patients (NYHA II-IV) with moderate to severe mitral stenosis
• Asymptomatic patients with pulmonary hypertension (≥50 mmHg at rest or ≥60 mmHg with exercise)
• Patients with high thromboembolic risk (history of systemic embolism, dense spontaneous contrast, new-onset atrial fibrillation) 1, 2

Expected outcomes from PMC: Mitral valve area increases from approximately 1.0 cm² to 1.7-2.0 cm², mean gradient decreases from 14-16 mmHg to 6-7 mmHg, and pulmonary artery pressure decreases significantly 1

Unfavorable Valve Anatomy

Proceed directly to surgical mitral valve replacement or open commissurotomy when: 1, 3

• Severe or bicommissural calcification is present
• Parachute mitral valve or supramitral ring exists
• Extensive subvalvular apparatus destruction
• More than mild mitral regurgitation coexists
• Left atrial thrombus is present (absolute contraindication to PMC) 4

In young patients with mild to moderate mitral regurgitation and favorable anatomy, open surgical commissurotomy may be preferred by experienced surgical teams over PMC 1

High Surgical Risk Patients with Calcified Valves

PMC should be considered as initial palliative treatment (Class IIa indication) even with calcified valves if the patient is a high-risk surgical candidate 1, 3

Management of Atrial Fibrillation

If atrial fibrillation is present (common in mitral stenosis):

• Initiate immediate anticoagulation with warfarin (target INR 2.0-3.0) regardless of CHA₂DS₂-VASc score, as mitral stenosis itself confers high thromboembolic risk 2, 4, 5, 6
• Achieve strict heart rate control with beta-blockers, rate-limiting calcium channel blockers (verapamil, diltiazem), or digoxin to prolong diastolic filling time and prevent pulmonary congestion 3, 2, 4
• Target heart rate <80 bpm at rest and <110 bpm with exercise as tachycardia is the primary trigger for acute decompensation 3, 2
• New-onset atrial fibrillation in asymptomatic patients with moderate to severe mitral stenosis is a Class IIb indication for PMC (after excluding left atrial thrombus) 1

Important caveat: Patients with atrial fibrillation have lower cardiac outputs and smaller final valve areas after PMC compared to those in sinus rhythm (1.6 cm² vs 1.8 cm²), but long-term outcomes at 5 years are similar between groups 7

Medical Management (Purely Palliative)

Medical therapy does not prevent disease progression but can temporize symptoms: 2, 4

• Diuretics to reduce pulmonary congestion and peripheral edema 3, 4
• Heart rate control agents (beta-blockers preferred) to prolong diastolic filling time 3, 2, 4
• Anticoagulation with warfarin (INR 2.0-3.0) for atrial fibrillation, history of embolism, left atrial thrombus, dense spontaneous contrast, or enlarged left atrium (>50 mm diameter or >60 mL/m²) 2, 4, 5

Critical perioperative warning: Avoid vasopressors like midodrine in mitral stenosis, as increased afterload reduces cardiac output and exacerbates pulmonary congestion 3

Special Clinical Scenarios

Asymptomatic Patients Requiring Intervention

PMC is indicated even without symptoms if: 1, 2

• Pulmonary artery systolic pressure >50 mmHg at rest
• Need for major non-cardiac surgery
• Desire for pregnancy (pregnancy increases cardiac output and can precipitate heart failure) 3, 2

Degenerative/Calcific Mitral Stenosis in Elderly

This is a distinct entity from rheumatic disease: 1, 8, 9

• Extensive annular calcification without commissural fusion makes PMC ineffective 1, 4, 8
• Surgical valve replacement is very high risk in this population 1, 9
• Transcatheter mitral valve replacement (using TAVI bioprostheses) is emerging as a feasible option for inoperable patients, though left ventricular outflow tract obstruction remains a significant concern 1, 9

Restenosis After Prior Intervention

When symptomatic restenosis occurs: 1

• PMC can be considered if the predominant mechanism is commissural refusion and valve characteristics remain favorable 1
• Most cases require valve replacement 1

Post-Intervention Follow-Up

After successful PMC: 1, 2, 4

• Follow-up similar to asymptomatic patients with yearly clinical and echocardiographic examinations
• More frequent monitoring if asymptomatic restenosis develops
• If PMC is unsuccessful, surgery should be considered early unless definite contraindications exist 1

Common Pitfalls to Avoid

• Do not use NOACs (non-vitamin K antagonist oral anticoagulants) in moderate to severe mitral stenosis—warfarin is mandatory due to lack of data supporting NOAC efficacy in this population 6
• Do not delay intervention in symptomatic patients—irreversible pulmonary hypertension and right heart failure can develop 2
• Do not assume asymptomatic status based on patient report alone—family members may observe diminished activity levels that patients are unaware of due to gradual adaptation 4
• Do not perform PMC without excluding left atrial thrombus via TEE—this is an absolute contraindication 1, 4