Mitral Stenosis ✅

Related Subjects: | Mitral Regurgitation (Incompetence) | Mitral Stenosis | Mitral Stenosis vs Regurgitation | Mitral Valve Prolapse | Atrial Fibrillation (AF) | Cardiac Valve Replacement | Prosthetic Valves |Acute Heart Failure and Pulmonary Oedema |Aortic Regurgitation (Incompetence) |Aortic Stenosis |Aortic Sclerosis |Transcatheter aortic valve implantation (TAVI) |Infective Endocarditis

📖 About Mitral Valve Disease (Mitral Stenosis)

Mitral stenosis (MS) is narrowing of the mitral valve, causing obstruction to blood flow from the left atrium (LA) to the left ventricle (LV) during diastole. This raises LA pressure, leading to pulmonary congestion, reduced LV filling, and eventually pulmonary hypertension, right heart strain, and atrial fibrillation.

• 🌍 Most common cause worldwide: rheumatic heart disease.
• 👵 In older patients in the UK: degenerative / calcific disease may contribute, although true rheumatic-type MS is less common.
• 📏 Normal mitral valve area: around 4–6 cm².
• ⚠️ Symptoms often begin when the valve area falls below about 2 cm².
• 🚨 Severe MS is usually <1.5 cm², with very severe disease often <1.0 cm²; however, severity should be judged using multiple echo parameters, not valve area alone.

🧬 Aetiology

• ❤️ Rheumatic heart disease: leaflet thickening, commissural fusion and shortening/fusion of the subvalvular apparatus → classic "fish-mouth" appearance.
• 🧒 Congenital MS: e.g. parachute mitral valve, supramitral ring, commissural fusion; often associated with other congenital lesions.
• 🪨 Mitral annular / leaflet calcification: more common in older adults, CKD, and long-standing degenerative valve disease.
• ☢️ Rare causes: prior chest radiation, connective tissue disease, mucopolysaccharidoses, carcinoid-related valve pathology.
• 🧱 Functional obstruction / MS mimic:
  • 🎭 Left atrial myxoma
  • 🩸 Left atrial thrombus
  • 🫀 Cor triatriatum
  • 📈 Severe HOCM causing impaired LV inflow
• 🔗 Lutembacher syndrome: mitral stenosis with an atrial septal defect.

🧠 Pathophysiology

• ⬇️ Narrowed mitral valve → impaired LV filling during diastole.
• ⬆️ LA pressure → LA enlargement and predisposition to atrial fibrillation.
• 🌬️ Back-pressure into pulmonary veins → dyspnoea, orthopnoea, and pulmonary oedema.
• 🫁 Long-standing pulmonary venous hypertension can lead to reactive pulmonary arterial hypertension.
• 💥 Increased RV afterload → right ventricular hypertrophy and later right heart failure.
• ⏱️ Tachycardia worsens symptoms because it shortens diastole, reducing time for blood to cross the stenotic valve.

🩺 Clinical Features

• 😮‍💨 Symptoms: exertional dyspnoea, orthopnoea, PND, reduced exercise tolerance, fatigue, palpitations, haemoptysis.
• 🫀 AF symptoms: palpitations, dizziness, sudden worsening breathlessness, acute pulmonary oedema.
• 👩 Classic appearance: malar flush may be seen in severe longstanding disease.
• 🖐️ Pulse: may be irregularly irregular in AF; often low volume.
• 📍 Apex beat: tapping, palpable first heart sound in some patients.
• 🔊 Heart sounds: loud S1, opening snap after S2, followed by a low-pitched mid-diastolic rumble best heard at the apex with the bell in the left lateral position.
• 📉 Severity clue: the shorter the S2–opening snap interval, the higher the LA pressure and generally the more severe the stenosis.
• 🫁 Pulmonary hypertension signs: loud P2, RV heave / parasternal lift.
• 🧠 Complications from LA enlargement: embolic stroke, hoarseness from left recurrent laryngeal nerve compression (Ortner syndrome), and sometimes dysphagia from oesophageal compression.

🚨 Decompensation Triggers

• 🏃 Exercise or emotional stress
• 🤒 Infection / sepsis
• 🤰 Pregnancy
• ⚡ Rapid AF or other tachyarrhythmias
• 💧 Fluid overload

🔍 Differential Diagnosis / Mimics

• 🎭 Left atrial myxoma – may produce positional symptoms and a “tumour plop”.
• 🫀 Tricuspid stenosis
• 💓 Severe mitral regurgitation with flow murmur
• 🧱 Mitral annular calcification with functional inflow obstruction

🧪 Investigations

• 📈 ECG:
  • AF is common
  • P mitrale = broad, notched P waves from left atrial enlargement
  • RVH / right axis deviation if pulmonary hypertension develops
• 🩻 CXR: left atrial enlargement, straightening of the left heart border, upper lobe diversion, pulmonary oedema, and features of pulmonary hypertension in advanced disease.
• 🫀 Transthoracic echocardiography (TTE): the key first-line test. Assesses valve morphology, leaflet mobility, commissural fusion, valve area, mean gradient, LA size, pulmonary pressures, MR, and suitability for balloon intervention.
• 🔎 TOE / TEE: useful if TTE images are limited, to better define anatomy, or to exclude left atrial appendage thrombus before cardioversion or percutaneous intervention.
• 🧪 Blood tests: FBC, U&E, LFTs, CRP, TFTs if AF present, BNP if breathlessness differential is unclear.
• 🧵 Cardiac catheterisation: now mainly reserved for selected cases when non-invasive assessment is uncertain or when coronary anatomy/intervention planning is needed.

📏 Severity

• ✅ Normal valve area: 4–6 cm²
• 🟢 Mild MS: >1.5 cm²
• 🟡 Moderate MS: 1.0–1.5 cm²
• 🔴 Severe MS: <1.0–1.5 cm² depending on context and associated haemodynamics

⚠️ Do not judge severity by valve area alone. Mean gradient, heart rate, rhythm (especially AF), pulmonary pressures, symptoms, and valve morphology all matter.

⚠️ Complications

• 💓 Atrial fibrillation
• 🧠 Systemic thromboembolism / embolic stroke
• 🫁 Pulmonary hypertension
• 🫀 Right ventricular failure
• 🩸 Haemoptysis
• 🗣️ Hoarseness (Ortner syndrome)
• 🍽️ Dysphagia from massive LA enlargement
• 🦠 Infective endocarditis is uncommon in isolated MS

💊 Anticoagulation pearl: In AF with clinically significant / moderate–severe mitral stenosis, use warfarin rather than a DOAC.

💊 Management

• 🩺 Medical treatment
  • 💦 Diuretics for pulmonary congestion and oedema.
  • ⏱️ Rate control if AF or sinus tachycardia worsens symptoms:
    • β-blockers are often helpful
    • Rate-limiting calcium-channel blockers may be used in selected patients
    • Digoxin may help in AF, especially if there is heart failure
  • 🩸 Anticoagulation: warfarin if AF is present in clinically significant MS; also consider anticoagulation if there has been systemic embolism or LA thrombus.
• 🛠️ Intervention
  • 🎈 Percutaneous mitral balloon commissurotomy / valvotomy is preferred in symptomatic severe MS if valve anatomy is favourable and there is no significant MR and no LA thrombus.
  • 🔪 Surgery / valve replacement is considered when balloon valvotomy is unsuitable, anatomy is heavily calcified, subvalvular disease is marked, or there is associated significant MR.
• 👶 Pregnancy
  • 🤰 Pregnancy increases blood volume and heart rate, so MS may decompensate rapidly.
  • 📋 Severe or symptomatic MS requires pre-pregnancy specialist counselling.
  • 💊 During pregnancy: careful fluid balance, beta-blockers where appropriate, and diuretics if needed.
  • 🛠️ Balloon valvotomy may be considered if symptoms remain severe despite medical treatment.
• 🌿 Lifestyle / follow-up
  • 🧂 Avoid excessive salt if congested
  • 🏃 Avoid strenuous exertion if symptomatic
  • 🩻 Regular echo follow-up depending on severity and symptoms
  • 📞 Seek urgent review if sudden worsening breathlessness, palpitations, syncope, or haemoptysis develops

🩺 Case 1 – Young Woman with Rheumatic Mitral Stenosis

A 28-year-old woman from South Asia presents with progressive exertional breathlessness, orthopnoea and palpitations. Examination shows malar flush, a tapping apex beat, loud S1 and an opening snap followed by a mid-diastolic murmur at the apex. Echo confirms moderate mitral stenosis.

• ✅ Likely approach: beta-blocker if tachycardic / symptomatic, diuretics if congested, anticoagulation if AF develops, specialist follow-up with repeat echo.
• 🎈 If symptoms progress and anatomy is suitable: consider percutaneous balloon valvotomy.
• ⚠️ Avoid: untreated tachycardia, poor follow-up, and pregnancy without specialist counselling if disease becomes severe.

🩺 Case 2 – Older Patient with Severe Calcific MS and AF

A 70-year-old man presents with worsening dyspnoea, ankle swelling and haemoptysis. He has an irregularly irregular pulse. Echo shows severe calcific mitral stenosis, marked LA enlargement and pulmonary hypertension.

• ✅ Management: warfarin for AF, diuretics for congestion, rate control, and specialist valve-team referral.
• 🔪 Likely intervention: surgery / valve replacement rather than balloon valvotomy if the valve is heavily calcified.
• ⚠️ Avoid: delaying referral, allowing uncontrolled AF, or assuming pulmonary vasodilators are routine treatment for MS-related pulmonary hypertension.

💡 High-Yield Exam Pearls

• 🎓 Rheumatic disease is the classic cause of true MS worldwide.
• 🎓 AF is common because chronic pressure overload enlarges the LA.
• 🎓 Tachycardia worsens MS because it shortens diastole.
• 🎓 Loud S1 + opening snap + mid-diastolic rumble at the apex = classic exam finding.
• 🎓 A shorter S2–opening snap interval suggests more severe disease.
• 🎓 TTE is the main diagnostic test; TOE is especially useful for thrombus exclusion and procedural planning.
• 🎓 In AF with significant MS, use warfarin, not a DOAC.
• 🎓 Balloon commissurotomy is first choice when anatomy is favourable.

📚 References

• 📘 NICE Guideline NG208: Heart valve disease presenting in adults: investigation and management. National Institute for Health and Care Excellence, 2021 (last reviewed 2025).
• 🫀 British Society of Echocardiography (BSE): Robinson S, et al. The assessment of mitral valve disease: a guideline from the British Society of Echocardiography. Echo Research & Practice, 2021.
• 🌍 ESC/EACTS Guidelines: Vahanian A, et al. 2025 ESC/EACTS Guidelines for the management of valvular heart disease. European Society of Cardiology / European Association for Cardio-Thoracic Surgery.
• 💊 BNF / NICE: Oral anticoagulants – Treatment Summary. British National Formulary, NICE.