Mitral Stenosis
Definition
Mitral stenosis (MS) is obstruction of diastolic flow from the LA to the LV due to structural abnormality of the mitral valve, leading to LA pressure overload, pulmonary congestion, and reduced cardiac output. Rheumatic fever is the most common aetiology worldwide; degenerative MS with mitral annular calcification (MAC) is a distinct pathology increasingly encountered in elderly patients.
Key Concepts
Rheumatic Mitral Stenosis
- Most common aetiology globally; mainly affects young patients and women in low-income countries; declining in high-income countries
- MVA ≤1.5 cm² = clinically severe rheumatic MS
- Evaluation: 2D planimetry (most common), 3D TTE/TOE for additional detail; mean gradient and pulmonary pressures have prognostic value
- Subvalvular involvement (leaflet/chordal calcification, commissural fusion) is the key determinant of suitability for percutaneous mitral commissurotomy (PMC)
- TOE mandatory in PMC candidates to exclude LA thrombus; and in those with recent embolism sources/vhd-esc-2025
very high
Anticoagulation in Rheumatic MS
- VKA with INR target 2–3 mandatory if AF coexists with MVA ≤2.0 cm²
- DOACs are contraindicated (Class III B) in patients with rheumatic MS and MVA ≤2.0 cm² — based on RCT subgroup analyses showing inferior outcomes vs VKA
- In sinus rhythm: OAC indicated after systemic embolism, LA thrombus, or dense LA spontaneous contrast / enlarged LA (M-mode >50 mm or volume >60 mL/m²) sources/vhd-esc-2025
very high
Indications for Intervention — Rheumatic MS
- Class I B: PMC in symptomatic patients without unfavourable characteristics
- Class I C: PMC in any symptomatic patient with contraindication or high risk for surgery
- Class I C: MV surgery in symptomatic patients not suitable for PMC
- Class IIa C: PMC as initial treatment in symptomatic patients with suboptimal anatomy but no unfavourable clinical characteristics
- Class IIa C: PMC in asymptomatic patients without unfavourable characteristics and high thromboembolic risk (history of embolism, dense LA contrast, new-onset AF) or high haemodynamic decompensation risk (SPAP >50 mmHg, need for major NCS, pregnancy/desire for pregnancy)
Contraindications to PMC
- MVA >1.5 cm² (unless symptoms unexplained by another cause)
- LA thrombus (PMC possible after 1–3 months OAC if appendage-only thrombus resolves)
- MR more than mild
- Severe or bi-commissural calcification
- Absence of commissural fusion
- Severe concomitant AV disease or severe combined tricuspid stenosis + regurgitation requiring surgery
- Concomitant CAD requiring CABG sources/vhd-esc-2025
very high
Degenerative Mitral Stenosis with Mitral Annular Calcification (MAC)
- Distinct age-dependent pathology; predominantly elderly women with significant comorbidities
- MAC associated with increased risk of AF, stroke, and death independent of valve dysfunction
- Most MAC does not cause significant MV dysfunction; when MS occurs, calcific extension into leaflets or subvalvular apparatus
- Mean transmitral gradient associated with increased mortality irrespective of MR severity
- Evaluation: CCT mandatory if intervention planned (degree and location of calcification); TOE important (acoustic shadowing limits TTE planimetry)
- Indications: Intervention recommended when symptomatic and not responsive to medical therapy — but both PMC (no commissural fusion) and surgery are high-risk
- TMVI (Class IIb C, new 2025): Transcatheter MV implantation may be considered in symptomatic patients with extensive MAC and severe MV dysfunction at experienced Heart Valve Centres — risk of LVOT obstruction, valve embolisation, stroke, and haemolysis; mortality remains 10–30% at 1 year even after successful treatment sources/vhd-esc-2025
very high
Invasive Hemodynamic Assessment of MS
- Catheterization is indicated when noninvasive gradient/valve area estimates are inconsistent, or when symptoms or pulmonary hypertension appear disproportionate to echo severity sources/hemodynamics-circ-2012
high - PAWP overestimates true transmitral gradient by 30–50% even with phase-shift correction, due to pressure transmission delay through the pulmonary circulation; confirmed by simultaneous oximetry that the catheter is truly wedged sources/hemodynamics-circ-2012
high - Transseptal catheterization for direct left atrial pressure is mandatory when therapeutic decisions (e.g., PMC candidacy) depend on accurate gradient data sources/hemodynamics-circ-2012
high - Exercise hemodynamics (supine bicycle in cath lab): transmitral gradient and PAWP may rise dramatically at low workloads, unmasking haemodynamically significant MS that appears mild at rest sources/hemodynamics-circ-2012
high - Absolute pulmonary pressure measurements at catheterization are important to distinguish pulmonary hypertension secondary to MS, LV diastolic dysfunction, pulmonary veno-occlusive disease, or intrinsic pulmonary vascular disease sources/hemodynamics-circ-2012
high
Medical Therapy
- Diuretics, beta-blockers, digoxin, non-DHP calcium channel blockers, or ivabradine for symptomatic relief via heart rate control and volume management
- Cardioversion unlikely to succeed if severe untreated MS; can be attempted for recent-onset AF after successful PMC or in moderate MS with amiodarone
Follow-up
- Asymptomatic severe rheumatic MS without intervention: yearly TTE
- Moderate MS: follow-up every 2–3 years
- After PMC: post-procedural MVA and mean gradient are key outcome predictors; watch for asymptomatic restenosis; monitor other valve involvement sources/vhd-esc-2025
very high
Perioperative Management of MS and NCS
- Evaluate for MV intervention: Severe symptomatic MS should be evaluated for PMC or MV surgery before elevated-risk elective NCS — if MS is the primary driver of symptoms, correction of the stenosis is preferable to proceeding with NCS under haemodynamic compromise. (sources/periop-aha-2024, rating: very high)
- If MV intervention not feasible — invasive haemodynamic monitoring (COR 2a): Direct LA pressure monitoring or PA catheter may be considered to optimise fluid management, guide vasopressor use, and detect pulmonary oedema perioperatively. (sources/periop-aha-2024, rating: very high)
- Heart rate control (COR 2b): Tachycardia severely worsens transmitral gradient by reducing diastolic filling time — maintain strict heart rate control (target <80 bpm resting, <100 bpm with activity) using beta-blockers or rate-limiting CCBs; avoid atrial pacing and any agent causing tachycardia. (sources/periop-aha-2024, rating: very high)
- Haemodynamic goals: Low-to-normal heart rate; high-normal SVR (to maintain CO via adequate diastolic filling); adequate but not excessive preload (LA pressure dependant on mitral gradient — volume overload causes pulmonary oedema); sinus rhythm strongly preferable. (sources/periop-aha-2024, rating: very high)
Contradictions / Open Questions
- TMVI for degenerative MS/MAC: very limited evidence; complications (LVOT obstruction, embolisation, haemolysis) remain frequent; should be considered only at the most experienced Heart Valve Centres; Heart Team must avoid futility
- Low-gradient severe rheumatic MS (MVA <1.5 cm², mean gradient <10 mmHg): management challenging; often elderly with unfavourable anatomy; limited evidence
- PMC in suboptimal anatomy: outcome heterogeneous; operator experience plays a large role in outcome
Connections
- Related to concepts/Valvular-Heart-Disease
- Related to entities/Atrial-Fibrillation
- Related to entities/Pulmonary-Hypertension
- Related to concepts/Tricuspid-Regurgitation
- Related to concepts/Perioperative-Cardiovascular-Assessment
- Related to sources/periop-aha-2024