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Mitral Stenosis

Clinical Subject Page

Mitral Stenosis

Also called

Narrowing of the Mitral valve

ICD-10

I34.2

Specialty

Cardiology

Onset

chronic

Reviewed

June 2026

On This Page

Overview

Mitral stenosis (MS) is a narrowing of the mitral valve, which reduces blood flow from the left atrium to the left ventricle. This causes increased pressure in the left atrium, leading to pulmonary congestion, pulmonary hypertension, and eventually heart failure if untreated.

Etiology & Risk Factors

Most Common Cause

  • Rheumatic fever (most common cause worldwide)

Other Causes

  • Calcification of the mitral valve annulus
  • Autoimmune diseases
    • Systemic lupus erythematosus (SLE)
    • Rheumatoid arthritis (RA)
  • Congenital mitral stenosis
  • Conditions that may mimic MS:
    • Bacterial endocarditis with large mitral valve vegetation
    • Left atrial myxoma
  • Degenerative aortic stenosis (may reduce the mitral annular area)

Risk Factors

  • History of rheumatic fever (most important risk factor)
  • Increasing age (risk of mitral annular calcification)
  • Autoimmune diseases (e.g., SLE, RA)
  • Congenital heart disease

Pathophysiology

    • Mitral valve stenosis causes obstruction of blood flow from the left atrium (LA) to the left ventricle (LV).
    • This results in reduced LV filling during diastole → decreased stroke volume → decreased cardiac output (forward heart failure).
    • Blood backs up into the left atrium, causing increased left atrial pressure.
    • The increased pressure is transmitted to the pulmonary veins and lungs, leading to:
      • Pulmonary venous congestion
      • Cardiogenic pulmonary edema
      • Pulmonary hypertension
    • Long-standing pulmonary hypertension can cause right ventricular hypertrophy and right-sided (backward) heart failure.

    Simple Flow

    Mitral valve narrowing → Obstruction of LA → LV blood flow → ↑ Left atrial pressure → Pulmonary congestion → Pulmonary hypertension → Right ventricular hypertrophy → Right-sided heart failure

Clinical Presentation

  1. Common Symptoms

    • Dyspnea (shortness of breath) – most common symptom
    • Fatigue
    • Palpitations (often due to atrial fibrillation)
    • Orthopnea
    • Paroxysmal nocturnal dyspnea (PND)
    • Hemoptysis
    • Hoarseness (Ortner syndrome)
    • Dysphagia
    • Symptoms of embolic disease (e.g., stroke)

    Late Features

    • Symptoms of right-sided heart failure
      • Leg swelling (edema)
      • Increasing breathlessness

    Physical Examination

    • Irregular pulse (if atrial fibrillation is present)
    • Diastolic murmur heard best at the apex
    • Loud first heart sound (S1)
    • Opening snap after S2
    • Signs of right heart failure (e.g., peripheral edema)

History Taking

  • “Do you get short of breath when walking or climbing stairs?”
  • “Do you become breathless when lying flat?”
  • “Do you wake up at night feeling short of breath?”
  • “Do you feel your heart racing or skipping beats?”
  • “Do you feel tired more easily than before?”
  • “Have you coughed up blood?”
  • “Have you noticed swelling in your legs or ankles?”
  • “Have you ever had rheumatic fever or recurrent sore throats?”
  • “Have you ever had a stroke or sudden weakness?”
  •  

Mitral Stenosis Vs Mitral Regurgitation

Cardiology · Valvular Heart Disease — Mitral Stenosis vs Mitral Regurgitation

🚧 Mitral Stenosis
Narrowed mitral valve orifice → obstructed LA→LV flow
Normal area: 4–6 cm²  |  Severe: <1 cm²
Most common cause: Rheumatic fever
↺ Mitral Regurgitation
Incompetent mitral valve → systolic backflow LV→LA
Volume overload of both LA and LV
Most common cause: MVP / rheumatic / ischaemic
Pathophysiology
Mitral Stenosis
Valve orifice narrows → pressure gradient across MV during diastole
LA pressure rises → LA enlargement + pulmonary venous HTN
Pulmonary HTN → RV pressure overload → cor pulmonale
LV is underfilled (preload ↓) — LV function usually preserved
AF common due to LA dilation → risk of LA thrombus → stroke
Mitral Regurgitation
Systolic backflow LV→LA → LA volume overload
LA enlarges → increased pulmonary venous return → LV volume overload
Compensated phase: LV dilates (eccentric hypertrophy), EF appears normal
Decompensated: LV contractility fails → EF falls → HF
Acute MR (papillary rupture/chordae): no time to compensate → flash pulmonary oedema
Auscultation & Heart Sounds
Mitral Stenosis
Murmur Mid-diastolic rumble at apex
Timing Diastolic — after S2, continues toward S1
Radiation Does not radiate
Character Low-pitched, rumbling
Special Loud S1  |  Opening snap after S2
Positional Louder in left lateral decubitus

S1┈┈┈S2┈OS┈╾╾╾rumble╿╿╿┈S1
└ Shorter S2–OS interval = more severe stenosis (higher LA pressure)
Presystolic accentuation (if sinus rhythm) — murmur increases just before S1
S1 loudness ↓ as stenosis worsens (valve less mobile)
Mitral Regurgitation
Murmur Pansystolic (holosystolic) murmur at apex
Timing Throughout systole — S1 to S2
Radiation Axilla / left infrascapular
Character Blowing, high-pitched
Special Soft/absent S1  |  S3 gallop (volume overload)
Positional Louder with squatting & expiration

S1┈╾╾╾╾╾╾╾╾╾S2┈┈┈┈┈┈S1
└ Uniform throughout systole — does not change with S1 or S2
MVP exception: late systolic murmur preceded by mid-systolic click
Acute MR may have a soft or early systolic murmur (LA pressure equalises rapidly)
ECG Findings
Mitral Stenosis
P wave Broad, notched P in II — “P mitrale” (>120 ms)
P in V1 Biphasic — prominent negative terminal deflection
QRS Usually normal (LV not overloaded)
Late finding RVH pattern (RAD, dominant R in V1) if pulmonary HTN
Rhythm Atrial fibrillation common (LA dilation)

┈/╾╿┈P-mitrale┈┈┈┈narrow QRS┈┈┈┈
└ P mitrale = LA enlargement signature — notched P >2.5 mm wide in II
Mitral Regurgitation
P wave Broad, notched P — “P mitrale” (LA enlargement)
QRS LVH pattern — tall R in V5/V6, deep S in V1/V2
Axis LAD (LV volume overload)
Rhythm AF common (LA dilation, same as MS)
Key diff LVH present in MR — absent in MS

┈/╾╿┈P-mitrale┈┈tall QRS (LVH)┈┈
└ LVH on ECG = volume overload — key distinguisher from pure MS
CXR Findings
Mitral Stenosis
LA enlargement: double shadow right heart border, splaying of carina (>70°), posterior displacement of oesophagus on lateral
Pulmonary venous HTN: upper lobe diversion → Kerley B lines → pulmonary oedema
Mitral valve calcification visible on lateral CXR
LV size normal (underfilled)
Late: RV enlargement, prominent pulmonary arteries
Mitral Regurgitation
LA enlargement (same signs as MS but often more prominent in chronic MR)
LV enlargement — cardiomegaly with leftward and downward cardiac apex displacement
Pulmonary oedema in acute MR or decompensated chronic MR
Key difference: LV enlargement present in MR — absent (or even small LV) in MS
Echocardiography
Mitral Stenosis
Hockey stick deformity of anterior mitral leaflet (doming in diastole)
Reduced E-F slope on M-mode (slow valve opening)
Planimetry of MVA <1 cm² = severe; PHT method for area
Mean gradient >10 mmHg = severe (Doppler)
LA enlarged, LV normal or small; leaflet calcification/fusion assessed for PTMC suitability (Wilkins score)
Mitral Regurgitation
Colour Doppler: systolic jet from LV into LA (direction indicates mechanism)
EROA ≥0.4 cm² or RVol ≥60 ml = severe (PISA method)
LV dilated (EDV ↑) with preserved or reduced EF
LA enlarged; pulmonary vein systolic flow reversal in severe MR
Surgery indicated when EF ≤60% or ESD ≥40 mm (LV decompensation threshold)
Symptoms & Clinical Features
Mitral Stenosis
Exertional dyspnoea → orthopnoea → PND (pulmonary venous HTN)
Haemoptysis (pulmonary venous rupture or Eisenmenger)
Palpitations (AF) → systemic embolism / stroke
Malar flush (mitral facies) — peripheral vasoconstriction + facial telangiectasia
Hoarseness — Ortner syndrome (enlarged LA compressing recurrent laryngeal nerve)
Symptoms precipitated by: pregnancy, tachycardia, AF (loss of atrial kick)
Mitral Regurgitation
Chronic: long asymptomatic phase — compensated for years
Exertional dyspnoea, fatigue (reduced forward CO)
Palpitations (AF), orthopnoea, PND
Acute MR: sudden flash pulmonary oedema, cardiogenic shock (ruptured papillary muscle post-MI)
Hyperdynamic apex, laterally displaced (LV volume overload)
Feature Mitral Stenosis Mitral Regurgitation
Murmur timingMid-diastolic rumblePansystolic blowing
Best heardApex, left lateral decubitusApex, radiates to axilla
S1Loud (early) → soft (late/calcified)Soft / obscured
Extra soundsOpening snap (OS) after S2S3 gallop (volume overload)
ECG P waveP mitrale (broad, notched)P mitrale (broad, notched)
ECG QRSNormal (RVH if pulm HTN)LVH pattern
CXR heart sizeLA enlarged, LV normalLA + LV both enlarged
Pulmonary oedemaChronic (gradual venous HTN)Acute (sudden decompensation)
LV functionPreserved (underfilled)Dilated → EF may fall
AF riskVery high (thrombus → stroke)High (LA dilation)
Main causeRheumatic feverMVP, rheumatic, ischaemic, IE
InterventionPTMC (balloon) or MVRRepair preferred over replacement
Surgery triggerMVA <1.5 cm² + symptomsEF ≤60% or ESD ≥40 mm

Investigations

  • 1. Transthoracic Echocardiography (TTE) – Gold Standard

    • Most important test for diagnosis and treatment planning.
    • Shows:
      • Reduced mitral valve area (MVA) (≤ 1.5 cm² = severe MS)
      • Thickened, calcified mitral leaflets
      • Commissural fusion
      • Increased diastolic pressure gradient
      • Left atrial enlargement
      • Pulmonary hypertension
      • Right ventricular dilation

    2. ECG

    • May be normal early.
    • Can show:
      • Left atrial enlargement (P mitrale)
      • Atrial fibrillation
      • Right ventricular hypertrophy (late disease)

    3. Chest X-ray

    • Left atrial enlargement
    • Pulmonary congestion
    • Right ventricular enlargement

    4. Laboratory Tests

    • BNP/NT-proBNP
    • CBC
    • BMP
    • Liver function tests
    • CRP (if rheumatic heart disease is suspected)

    5. Additional Tests (when indicated)

    • Transesophageal echocardiography (TEE) before intervention or if TTE is inconclusive
    • Exercise stress test if symptoms do not match TTE findings
    • Cardiac catheterization if disease severity is unclear or before surgery

Diagnosis

  • Diagnostic Approach

    • Suspect MS based on symptoms (e.g., dyspnea, fatigue, palpitations) and physical examination.
    • Confirm the diagnosis with transthoracic echocardiography (TTE).

    Gold-Standard Test

    Transthoracic Echocardiography (TTE)

    • Best initial and most important test for diagnosing MS.
    • Typical findings:
      • Reduced mitral valve area (MVA)
      • MVA ≤ 1.5 cm² = severe mitral stenosis
      • Thickened, calcified mitral valve leaflets with commissural fusion
      • Increased mean diastolic pressure gradient
      • Left atrial enlargement
      • Pulmonary hypertension
      • Right ventricular dilation

    Supportive Tests

    • ECG
      • Left atrial enlargement (P mitrale)
      • Atrial fibrillation
      • Right ventricular hypertrophy (late finding)
    • Chest X-ray
      • Left atrial enlargement
      • Pulmonary congestion
      • Right ventricular enlargement
    • TEE
      • If TTE is inconclusive
      • Before intervention to detect left atrial thrombus or significant mitral regurgitation
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Management

1. Medical Management

  • Asymptomatic patients: Regular follow-up with TTE.
  • Treat heart failure symptoms and associated conditions.
  • Manage atrial fibrillation and other complications if present.

2. Interventional Management

Indications:

  • Symptomatic severe MS (MVA ≤ 1.5 cm²)
  • Asymptomatic severe MS with:
    • Pulmonary artery systolic pressure >50 mmHg, or
    • New-onset atrial fibrillation

3. Procedures

Percutaneous Mitral Balloon Commissurotomy (PMBC)

  • Preferred treatment for most patients with severe MS.
  • Balloon is used to open the narrowed mitral valve.

Surgery

  • Open commissurotomy or mitral valve replacement
  • Indicated if:
    • Anatomy is unsuitable for PMBC
    • Left atrial thrombus is present
    • Significant associated valve disease (e.g., severe mitral regurgitation)

Complications

    • Atrial fibrillation (AF) → increases the risk of thromboembolic events (e.g., stroke)
    • Pulmonary edema
    • Pulmonary hypertension
    • Congestive heart failure (CHF)
    • Enlarged left atrium causing:
      • Esophageal compression → dysphagia
      • Recurrent laryngeal nerve palsy → hoarseness (Ortner syndrome)

Prognosis

  • Mitral stenosis is slowly progressive, and many patients remain asymptomatic for years.
  • Prognosis worsens as the valve becomes more narrowed and complications such as atrial fibrillation, pulmonary hypertension, and heart failure develop.
  • Early diagnosis, regular follow-up, and timely intervention (e.g., balloon commissurotomy or surgery) improve outcomes
  •  

Key Points / Clinical Pearls

    • Most common cause: Rheumatic fever
    • Gold-standard test: Transthoracic echocardiography (TTE)
    • Classic murmur: Opening snap followed by a diastolic murmur at the apex
    • Most common symptom: Dyspnea
    • Severe MS: Mitral valve area ≤ 1.5 cm²
    • Preferred treatment for severe symptomatic MS: Percutaneous mitral balloon commissurotomy (PMBC)
    • Common complications: Atrial fibrillation, stroke, pulmonary hypertension, and heart failure