What is the overview of mitral stenosis management?

Mitral Stenosis Overview

Definition and Pathophysiology

Mitral stenosis is characterized by narrowing of the mitral valve orifice that obstructs left ventricular inflow, with severe disease defined as a valve area ≤1.0 cm² (normal >4 cm²), leading to elevated left atrial and pulmonary artery pressures. 1

• The mitral valve apparatus consists of four interconnected structures: the mitral annulus, the anterior and posterior leaflets, the chordae tendineae, and the papillary muscles—abnormalities in any component can result in stenosis 1
• Rheumatic MS accounts for 85% of all mitral stenosis cases worldwide and involves commissural fusion with thickening at the leaflet tips 1
• Degenerative MS results from mitral annular calcification (MAC) with progressive calcium deposition, valve thickening, and chordal shortening—notably without commissural fusion 1
• The incidence of rheumatic mitral stenosis has greatly decreased in industrialized countries, while degenerative calcific mitral valve disease is now encountered mainly in elderly patients 2

Diagnostic Assessment

Echocardiography is the preferred method for diagnosing mitral stenosis and assessing severity, with valve area by planimetry serving as the reference measurement. 2, 1

Key Echocardiographic Parameters:

• Severe MS criteria: MVA ≤1.0 cm², mean transmitral gradient ≥10 mmHg, diastolic pressure half-time ≥150 ms 1, 3
• Mean transvalvular gradient and pulmonary pressures reflect hemodynamic consequences and have prognostic value 2
• TOE should be performed to exclude LA thrombus before percutaneous mitral commissurotomy (PMC) or after an embolic episode 2
• Stress testing is indicated in patients with no symptoms or symptoms equivocal or discordant with the severity of mitral stenosis 2
• Exercise echocardiography provides additional objective information by assessing changes in mitral gradient and pulmonary artery pressure 2

Clinical Findings:

• Classic auscultatory finding is a low-pitched, rumbling diastolic murmur best heard at the apex with the bell of the stethoscope with the patient in the left lateral decubitus position 3
• An opening snap (OS) follows S2 and precedes the diastolic murmur—the interval between S2 and OS shortens as mitral stenosis severity increases 3
• First heart sound (S1) is typically accentuated due to prolonged closure of the mitral valve from high left atrial pressure 3

Medical Management

Medical therapy is palliative and does not prevent disease progression; it focuses on symptom relief and complication prevention while monitoring for indications for intervention. 4

Symptom Control:

• Diuretics are recommended for symptom relief when edema or congestion is present 4, 3
• Heart rate control with beta-blockers or calcium channel blockers is effective for symptom relief in patients with atrial fibrillation to prolong diastolic filling time 4, 3
• Digoxin is recommended for heart rate control specifically in patients with atrial fibrillation and mitral stenosis 4, 3

Anticoagulation:

• Anticoagulation is indicated in patients with a history of systemic embolism 4, 3
• Anticoagulation is indicated in patients with dense spontaneous contrast in the left atrium on echocardiography 4, 3
• Anticoagulation is indicated in patients with an enlarged left atrium (M-mode diameter >60 mL/m²) 4, 3
• Patients with mitral stenosis and atrial fibrillation should be kept on vitamin K antagonists and not receive NOACs 4, 3

Indications for Intervention

Intervention should be limited to patients with clinically significant (moderate to severe) mitral stenosis with valve area <1.5 cm². 2, 1

Symptomatic Patients:

• NYHA class II-IV symptoms with severe MS (MVA ≤1.5 cm²) warrant intervention 1, 3
• PMC may be considered in symptomatic patients with a valve area >1.5 cm² if symptoms cannot be explained by another cause and if the anatomy is favorable 2

Asymptomatic Patients with High-Risk Features:

• Elevated pulmonary artery systolic pressure >50 mmHg at rest 2, 4, 3
• New-onset atrial fibrillation 4, 3
• High risk of thromboembolism (history of systemic embolism, dense spontaneous contrast in the left atrium) 2, 4, 3
• Need for major non-cardiac surgery or desire for pregnancy 2

Treatment Options

Percutaneous mitral balloon commissurotomy (PMC) is the first-line intervention for symptomatic severe rheumatic MS with favorable valve morphology. 4, 1, 3

PMC Indications:

• Favorable valve morphology with minimal calcification and no significant mitral regurgitation 3
• Suitable for patients with previous surgical commissurotomy if valve morphology remains favorable 2
• Contraindications include: LA thrombi, pre-existing >Grade II mitral regurgitation, marked degenerative destruction of the subvalvular apparatus, or extensive calcification 2

Surgical Options:

• Open mitral commissurotomy for patients with favorable valve anatomy but unsuitable for PMC 3
• Mitral valve replacement should be considered as the primary surgical option for degenerative MS 1
• Mitral valve replacement for patients with unfavorable valve anatomy (heavy calcification, significant subvalvular fusion) 3

Monitoring and Follow-up

Asymptomatic severe mitral stenosis requires echocardiographic assessment every 2-3 years, with more frequent monitoring for very severe stenosis or borderline hemodynamics. 1, 3

• Yearly monitoring is appropriate for patients with very severe stenosis 1
• Clinical evaluation for development of symptoms, atrial fibrillation, or pulmonary hypertension 3
• Regular echocardiographic assessment is essential to monitor disease progression 4

Common Pitfalls and Caveats

• Medical therapy alone is palliative and does not prevent disease progression; regular monitoring for development of indications for intervention is essential 4
• Accurate assessment of MVA in patients with MAC is challenging due to alterations in atrial and valvular structures 5
• Degenerative MS presents unique challenges as percutaneous or surgical commissurotomy is rarely employed due to extensive annular calcification without commissural fusion 6
• The type of treatment and its timing should be decided based on clinical characteristics, valve anatomy, and local expertise 2