Mitral Stenosis

Meet the patient

A 28-year-old woman, 26 weeks pregnant, is brought to the emergency department at midnight. She has woken gasping, coughing up pink froth, and her pulse is fast and completely irregular. She has a plum-coloured flush across her cheeks, and when you listen at the apex in the left lateral position you hear a loud snapping first sound, a click just after the second sound, and a low rumble running through diastole.^[1][2]

She has never been told she had a heart problem. The registrar reaches for the GTN infusion and the ACE-inhibitor — and that is precisely the wrong move, because this ventricle is preload-dependent behind a fixed obstruction, and a vasodilator will drop her pressure through the floor.^[1]

The exam question hiding in this bed is previously silent rheumatic mitral stenosis, decompensated by pregnancy and new atrial fibrillation. Everything below exists to make you reach for rate control and the echo first, to know the auscultatory triad on first hearing it, and to choose PMC versus MVR by the anatomy, not the murmur.^[1][9]

What mitral stenosis is — and why it is the most satisfying valve lesion

Mitral stenosis is a narrowing of the mitral valve orifice that obstructs diastolic flow from the left atrium (LA) to the left ventricle (LV). The valve opens passively during early LV relaxation, driven by the LA-to-LV pressure gradient; with stenosis, diastolic flow requires a sustained pressure gradient, and the left atrial pressure rises in proportion to the severity of narrowing.^[1][2]

The normal mitral valve area (MVA) is 4 to 6 cm squared. Clinical impact appears as the area falls: MVA under 1.5 cm squared is severe; under 1.0 cm squared is very severe; symptoms at rest are uncommon until the area is well below 1.5 cm squared and the mean transmitral gradient exceeds about 10 mmHg, with secondary pulmonary hypertension.^[1][2][10]

Why MS rewards knowing it well:^[1]

• It is a mechanical obstruction with a mechanical cure — the most satisfying valvular lesion, because the natural history can be normalised by PMC or MVR, unlike aortic stenosis (almost always replaced) or MR (repair versus replacement depending on aetiology).^[1][2]
• It is the dominant remaining valvular disease of the developing world (rheumatic heart disease), so its epidemiology, presentation and prevention strategy are high-yield for international exams (NEET-PG, INICET).^[9]
• The exam loves the mitral auscultatory triad and the ways the findings change with severity, posture, atrial rhythm and intervention.^[1][2]
• Management requires a precise anatomy-driven decision — PMC versus MVR — that exercises the candidate's understanding of valve morphology (Wilkins score, Cormier classification), and an evidence-based anticoagulation strategy — warfarin for valvular AF, not DOACs.^[10][11]

Classification — severity by area, anatomy by Wilkins

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Severity is graded by valve area, mean gradient and pulmonary pressure (haemodynamic classification), and intervention candidacy is graded by anatomy (Wilkins and Cormier) and by aetiology.^[1]

Severity (haemodynamic)

^{[7] [19] [20]}

Two gradings coexist and examiners use both. The echocardiographic grading describes the lesion (mild MVA over 1.5, moderate 1.0 to 1.5, severe under 1.0 cm squared; mean gradient under 5, 5 to 10, over 10 mmHg; PASP under 30, 30 to 50, over 50 mmHg, measured at heart rates of 60 to 80 in sinus rhythm)^[20], while the guidelines define clinically significant MS as MVA at or below 1.5 cm squared — the threshold at which intervention is considered — and very severe MS as MVA at or below 1.0 cm squared^[7][19]. On continuous-wave Doppler, MVA equals 220 divided by the pressure half-time (PHT) (the empirical Hatle formula), so PHT 150 ms or more corresponds to severe and 220 ms or more to very severe MS^[20][19]. The Wilkins echocardiographic score (Wilkins, Weyman, Abascal; Br Heart J 1988) sums four components graded 1 to 4 each — leaflet mobility, leaflet thickening, subvalvular thickening, calcification — total range 4 to 16. A score at or below 8 with pliable non-calcified leaflets is favourable for PMC. The Cormier classification groups anatomy into three classes (group 1: pliable non-calcified anterior leaflet with mild subvalvular disease — ideal; group 2: pliable non-calcified anterior leaflet with severe subvalvular disease; group 3: calcification of the mitral valve of any extent as assessed by fluoroscopy — an unfavourable characteristic for PMC).^[8][7]

Classification by aetiology

^{[1] [2] [5] [9]}

Epidemiology — the disease that geography decides

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The dominant cause of MS worldwide is rheumatic heart disease (RHD) — a sequela of acute rheumatic fever (ARF) following inadequately treated group-A beta-haemolytic streptococcal pharyngitis (Streptococcus pyogenes). Although ARF and chronic RHD have all but disappeared from high-income countries with widespread penicillin treatment, RHD remains a leading cause of cardiovascular morbidity and mortality in low- and middle-income countries (South Asia, sub-Saharan Africa, Indigenous Australia, parts of Latin America).^[1][5][9]

Key epidemiological facts:^[1]

• Women predominate — both rheumatic and degenerative MS are commoner in females; 72 percent of the 4,531 patients with rheumatic-heart-disease AF in INVICTUS were women.^[7][22]
• Symptomatic MS typically presents in the third to fourth decade — two decades or more after the index attack of ARF, which occurs at 5 to 15 years of age.^[23][5]
• Genetic susceptibility contributes — familial clustering, with rheumatic-fever concordance of 19 percent in monozygotic versus 2.5 percent in dizygotic twins, and HLA class II DR/DQ associations that differ by population (HLA-DR15, DRB4, DRB5 and DQB102 in a North Indian RHD cohort).^[26][9]
• Socioeconomic risk factors: overcrowding, poverty, limited access to primary care and to benzathine penicillin G prophylaxis, recurrent streptococcal pharyngitis, and high background RHD prevalence.^[5][9]

^{[7] [19] [22] [24]}

Risk-factor summary:^[1]

• Prior acute rheumatic fever (the strongest clinical antecedent) — occurs at age 5 to 15 in the index attack.^[5]
• Lack of or non-adherence to secondary prophylaxis (benzathine penicillin G 1.2 million units IM monthly).^[5]
• Multiple recurrences of ARF — each recurrence accelerates valve damage.^[5][9]
• Chronic kidney disease, diabetes, hyperparathyroidism — predispose to calcific or degenerative MS (a different aetiology, prominent in elderly patients).
• Female sex for the rheumatic form.^[9]
• Tachycardia of any cause (pregnancy, fever, atrial fibrillation, hyperthyroidism) precipitates decompensation by shortening diastolic filling time and raising the transmitral gradient.^[1][5][9]

Pathophysiology — the pressure cascade and the preload-dependence paradox

Enlarge

The pathological hallmark of rheumatic MS is commissural fusion accompanied by leaflet thickening, fibrosis and variable calcification, plus subvalvular chordal shortening and fusion — the fish-mouth or buttonhole orifice when viewed from the LA in severe disease.^[1][2][9]

The functional consequence is a fixed obstruction to diastolic flow — flow is now driven by a sustained pressure gradient across the valve, and the LA pressure rises in proportion to severity, modulated by the cardiac cycle and heart rate.^[1]

The pressure cascade — eight steps to right-heart failure

1. Raised LA pressure. The LA-to-LV diastolic gradient rises from a few mmHg (normal) to 10 mmHg or above (severe MS) as the area falls. LA pressure elevation is the initiating event of every downstream consequence.^[1][2]
2. Pulmonary venous congestion. The raised LA pressure transmits back through the pulmonary veins, raising pulmonary capillary wedge pressure and producing exertional dyspnoea, orthopnoea and paroxysmal nocturnal dyspnoea when capillary hydrostatic pressure exceeds plasma oncotic reserve.^[1]
3. Reactive pulmonary arterial hypertension (PAH). Sustained pulmonary venous hypertension triggers a reactive, vasoconstrictive component — intimal proliferation, medial hypertrophy and plexogenic arteriopathy in the pulmonary arterioles. Right ventricular pressure overload and right ventricular failure follow when the PAH becomes severe (PASP above 50 mmHg).^[1][2][7]
4. Atrial enlargement and AF. The chronic pressure and volume load on the LA dilates it (a giant LA — sometimes the whole left cardiac silhouette on chest X-ray), and atrial fibrillation develops in about 30 percent of patients with isolated rheumatic MS (29 percent in a prospective series of rheumatic valvular disease, with age and LA diameter the strongest predictors). AF is dangerous in MS for two reasons: filling across the obstructed valve depends heavily on the atrial kick, which AF abolishes, and the irregularly rapid ventricular response shortens diastole and elevates the transmitral gradient — a perfect storm for acute pulmonary oedema.^{[24][27][1][2]}
5. Thromboembolism. Sluggish flow in the dilated LA, particularly in the left atrial appendage, predisposes to thrombus. Systemic embolism (cerebral, mesenteric, renal, peripheral) may be the first clinical manifestation of previously silent MS: in a prospective cohort of 534 patients with an MVA of 2.0 cm squared or less, LA thrombus, a smaller valve area and older age predicted embolism in sinus rhythm, and previous embolism predicted recurrence in AF.^[25][1]
6. Haemoptysis. Rupture of pulmonary venules from raised pulmonary venous pressure produces pink frothy sputum or frank haemoptysis — an early symptom, frequently dismissed as "bronchitis" or "pulmonary tuberculosis" in endemic regions.^[1]
7. Ortner syndrome. The enlarged LA or dilated pulmonary artery compresses the left recurrent laryngeal nerve, producing hoarseness — the Ortner (cardiovocal) syndrome, a high-yield clinical pearl unique to severe MS or other causes of a giant LA or PA.^[6]
8. Tachycardia precipitates decompensation. Any cause of tachycardia (AF with rapid rate, exertion, fever, pregnancy, hyperthyroidism) shortens diastolic filling time, raises the transmitral gradient (because flow per unit time must be pushed through a smaller area), and can precipitate acute pulmonary oedema even in a previously stable patient.^[1][2][10]

Why MS kills: the preload-dependence paradox

The patient's forward cardiac output depends on adequate diastolic filling across the obstructed valve. Excessive preload reduction (large diuretic doses, nitrates) or excessive afterload reduction (ACE-inhibitors, ARBs, nifedipine, hydralazine) may collapse transvalvular flow before pulmonary pressures fall, precipitating hypotension and shock. This is the single most important reason MS patients do not respond to standard heart-failure afterload reducers — the valve, not the LV, is the bottleneck.^[1][2][10]

^{[1] [2] [8] [10]}

Clinical presentation — the young woman, the triad, the decompensation

The classic presentation is a young woman in her 20s to 40s from an endemic region presenting with exertional dyspnoea, sometimes with haemoptysis, palpitations (AF), a history of stroke or transient ischaemic attack (systemic embolism), or hoarseness (Ortner syndrome).^[1][2][9]

Symptoms (the high-yield list)

• Dyspnoea on exertion — the earliest and most common symptom; reflects pulmonary congestion as the gradient rises.^[1][2]
• Orthopnoea and paroxysmal nocturnal dyspnoea (PND) — with progression of LA pressure rise at rest; presents as night-time cough or wheeze (often misdiagnosed as asthma).^[1]
• Fatigue and effort intolerance — reduced cardiac output across a fixed obstruction.^[2]
• Palpitations — the onset of atrial fibrillation, often new, frequently symptomatic with breathlessness at rest.^[1][10]
• Haemoptysis — pink frothy sputum from pulmonary oedema, or frank red blood from ruptured pulmonary venules; an early symptom.^[1]
• Hoarseness — Ortner syndrome from compression of the left recurrent laryngeal nerve by the enlarged LA or pulmonary artery.^[6]
• Systemic embolism — stroke or peripheral ischaemia as the presenting feature of previously silent MS with AF.^[1][10][11]
• Chest pain — atypical, possibly reflecting coexistent coronary disease or pulmonary hypertension (RV ischaemia).^[2]

Signs — the bedside examination

General: mitral facies — a plum-coloured malar flush (a cyanotic cheek blush from peripheral vasoconstriction in chronic low output); the pulse may be irregularly irregular (AF) or regular; a tapping apical impulse (felt but not displaced — the loud S1 is felt as a tap).^[1][2]

Palpation: a diastolic thrill at the apex in severe disease; a right ventricular heave at the left sternal edge in pulmonary hypertension; a palpable P2 in the pulmonary area.^[2]

Auscultation (the mitral triad):^[1]

1. Loud (tapping) S1 — best heard at the apex; reflects a high transmitral gradient tensing the leaflets shut in early systole; softens as the valve becomes calcified and rigid.^[1]
2. Opening snap (OS) — a high-frequency sound after A2 at the apex or just medial to it; the A2-OS interval shortens with rising LA pressure and severity; an absent OS means calcified immobile valves.^[1][2]
3. Mid-diastolic rumble — a low-pitched rumble best heard at the apex with the bell in the left lateral position, beginning after the OS and lasting through to (or until) S1; the length of the murmur is a marker of severity; presystolic accentuation in sinus rhythm.^[1][2]

Signs of pulmonary hypertension and right-heart failure: loud P2, a right ventricular heave, a Graham Steell murmur — an early diastolic murmur of functional pulmonary regurgitation at the left sternal edge; a raised JVP with prominent a-waves (in sinus rhythm) or absent a-waves (in AF), tricuspid regurgitation, hepatomegaly, peripheral oedema, ascites.^[1][2]

Dynamic findings: the murmur lengthens with exertion and in the left lateral position (use both to bring out the murmur in a suspected case); the A2-OS interval shortens after exercise.^[1][2]

Atypical presentation

• Late disease with a soft S1 and absent OS — calcified rigid leaflets; severity is now read from haemodynamics, not auscultation.^[1][2]
• Asymptomatic severe MS — found incidentally on echo; becomes symptomatic with pregnancy, AF, fever, hyperthyroidism or anaemia.^[1][2]
• Pulmonary hypertension dominating the picture — RV heave, loud P2, peripheral oedema; the mitral findings may be subtle.^[2]
• Embolic stroke as the first presentation — silent MS presents with AF and cerebral embolism in a young patient; LA thrombus, a smaller valve area and older age were the predictors of embolism in a prospective MS cohort.^[25][1][2]

The differential — MS mimics and "pseudo-MS"

The differential is best framed in two groups: MS mimics (true diastolic obstruction of a different cause) and "pseudo-MS" (other causes of a diastolic murmur at the apex or pulmonary congestion).^[1][2][9]

^{[1] [2]}

The decisive single test for the MS differential is the transthoracic echocardiogram (TTE) — it confirms MS, excludes LA myxoma and cor triatriatum, grades severity, defines anatomy for intervention (leaflet mobility, calcification, MR, LA thrombus), and identifies pulmonary pressure.^[1][2]

Bedside assessment — confirm and quantify before the echo arrives

The bedside examination confirms suspected MS and quantifies severity before the echo arrives.^[1]

• General inspection — mitral facies (malar cyanotic flush), nutritional status (cachexia in advanced disease), any marfanoid habitus (consider an alternative diagnosis).^[1][2]
• Pulse — rate, rhythm (AF in about 30 percent of rheumatic MS), volume; pulsus parvus et tardus is NOT an MS finding (a small late pulse is aortic stenosis).^[24][2]
• JVP — raised with prominent a-waves in pulmonary hypertension and RV overload; giant a-waves with sinus rhythm suggest concomitant TS; a-waves are absent in AF.^[2]
• Palpation — tapping apex (not displaced); diastolic thrill at the apex in severe MS; left parasternal heave (RV hypertrophy); palpable P2 at the pulmonary area.^[1][2]
• Auscultation — the full mitral triad at the apex in the left lateral position; loud P2 and any Graham Steell murmur at the left sternal edge.^[1][2][7]

Dynamic manoeuvres to bring out a subtle murmur: exercise (lengthens the murmur), the left lateral position with the bell (murmur longest), expiration (brings the LV closer to the chest wall).^[1]

Severity clues at the bedside (haemodynamic, not just louder):^[1]

• A long murmur persisting close to S1 (in sinus rhythm) — more severe.^[1][2]
• A short A2-OS interval — the higher the LA pressure, the earlier the valve opens, so the interval shortens as stenosis worsens.^[1][2]
• A soft S1 plus absent OS — calcified rigid valve, often severe.^[2]
• Pulmonary hypertension signs — loud P2, RV heave, raised JVP, peripheral oedema — the more severe the sequelae, the more severe the MS driving them.^[1][7]

Investigations — echo is pivotal; everything else is context

Investigations establish the diagnosis, severity, anatomy, and comorbid status for intervention.^[1][2]

First-line

1. 12-lead ECG — left atrial enlargement (a broad, notched P wave in lead II — P mitrale; a biphasic P with deep terminal negativity in V1 — a P terminal force more negative than 0.04 mm·s, the Morris index); AF if an irregular narrow-complex rhythm without P waves; right-axis deviation, right ventricular hypertrophy in pulmonary hypertension.^[1][2]

2. Chest X-ray — straightening of the left cardiac border (enlarged LA appendage), double density at the right cardiac border (enlarged LA), widening of the carinal angle by the enlarged left atrium, pulmonary venous congestion, Kerley B lines, interstitial oedema, and in advanced disease prominent pulmonary arteries and right-heart enlargement.^[1]

3. Transthoracic echocardiogram (TTE) — the pivotal test. Confirms the diagnosis, measures MVA by planimetry, pressure half-time (PHT) and the continuity equation, mean and peak transmitral gradients by continuous-wave Doppler, pulmonary artery systolic pressure (PASP) from the tricuspid regurgitation velocity, LA size, RV size and function, concomitant MR, mitral leaflet anatomy (mobility, thickening, subvalvular, calcification — the Wilkins components), and excludes LA myxoma and cor triatriatum.^[1][2][8]

Pre-intervention

4. Transoesophageal echocardiogram (TOE) — mandatory before any percutaneous mitral commissurotomy (PMC) and before electrical cardioversion of AF in MS to exclude left atrial (LA) or left atrial appendage (LAA) thrombus; also used to refine anatomy when TTE is suboptimal.^[1][2]

5. ECG-gated cardiac CT — for valve calcification quantification when echo is equivocal, and coronary CT angiography for surgical planning in patients over 40.^[7]

6. Stress echocardiography — exercise echo is indicated when symptoms are absent, or equivocal or discordant with the resting severity; a mean gradient rising above 15 mmHg on exercise supports intervention when the resting MVA exceeds 1.5 cm squared, and an exercise systolic pulmonary pressure of 60 mmHg or more is a prognostic marker. Exercise is preferred to pharmacological stress because it reproduces physiological haemodynamics.^[7][19][23]

7. Cardiac catheterisation — rarely needed for diagnosis; used when non-invasive tests are discordant, or for coronary assessment before surgical MVR.^[1][2]

8. Cardiac MR (CMR) — an adjunct when echo is suboptimal or for RV quantification; not routine.^[2]

Named scores and criteria — reproduced verbatim

Wilkins echocardiographic score (Br Heart J 1988) — four components, each graded 1 to 4 (1 is normal or least, 4 is worst):^[8]

^{[8] [20]}

Total 4 to 16; at or below 8 is favourable for PMC.^[1]

^{[7] [20]}

Acute decompensation — rate control first, vasodilators last

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Acute decompensation in MS is usually driven by rate and rhythm (new fast AF), volume load (pregnancy, fluids), or failure of chronic management (missed prophylaxis, non-adherence). The pattern is typically acute pulmonary oedema with preserved or high blood pressure — the LV is fine, but the obstructed valve and rapid rate have precipitated congestion.^[1][2]

The first 30 minutes — the immediate priorities

1. Position upright, give high-flow oxygen to target SpO2 94 to 98 percent (the standard ward target range).^[1][13]
2. Two large-bore IV cannulae, cardiac monitoring, a 12-lead ECG (look for AF, new ischaemia).^[1]
3. IV loop diuretic to relieve pulmonary congestion; titrate to relief of pulmonary oedema and adequate urine output.^[1][2]
4. RATE CONTROL IS THE FIRST-LINE PRIORITY — slowing the heart rate lengthens diastole and reduces the transmitral gradient more effectively than pure preload reduction. Options:
   • IV metoprolol — in a randomised comparison in mild-to-moderate MS in sinus rhythm, an IV 5 mg metoprolol dose followed by oral metoprolol lowered the peak and mean transmitral gradients, lengthened treadmill exercise time and relieved dyspnoea in 18 of the 40 patients treated; the best first choice in a non-asthmatic. Rate control is a Class 2a recommendation in rheumatic MS with AF and a rapid ventricular response.^[16][1]
   • IV diltiazem 0.25 mg/kg over 2 min, then an infusion of 5 to 15 mg/hr, if beta-blockers are contraindicated — but in that same randomised trial (IV 25 mg then 3 months of oral diltiazem) diltiazem gave no symptomatic relief, no change in transmitral gradients and no gain in exercise time.^[16][2]
   • Digoxin, then oral maintenance — most useful in AF when rate control is difficult or LV dysfunction coexists.^[1][2]
5. Cardioversion if the patient is haemodynamically unstable (syncope, hypotension, refractory pulmonary oedema) and AF is of recent onset (under 48 h) or LAA thrombus has been excluded by TOE.^[1][2]
6. Anticoagulate if there is AF, prior embolism or LA thrombus — weight-based heparin (80 units/kg IV bolus then 18 units/kg/hr infusion) reaches therapeutic anticoagulation faster than fixed dosing; convert to oral anticoagulation once stabilised.^[1][12]

Specific ICU pearls (high-yield)

• Avoid aggressive afterload reduction (ACE-inhibitors, ARBs, nitroprusside, nifedipine) — the LV is preload-dependent; reducing afterload without relieving the mitral obstruction can precipitate hypotension and shock. A cautious IV nitrate infusion may help if BP permits and pulmonary oedema is severe, but rate control and diuresis do most of the work.^[1][2]
• Bilevel positive airway pressure (BiPAP) is highly effective in MS pulmonary oedema — titrate IPAP and EPAP to relieve the work of breathing and improve oxygenation while definitive rate control and diuresis take effect.^[1]
• Avoid digoxin in WPW with AF — risk of degeneration to VF; use ibutilide or procainamide if electrical cardioversion is unavailable; otherwise synchronised DCCV.^[2]

Definitive management — mechanical relief, anatomy-driven

Definitive management is mechanical relief of the obstruction in patients who meet criteria; the decision is anatomy-driven (PMC versus MVR).^[1][2][7]

Indications for intervention

Symptomatic severe MS (NYHA class II to IV, MVA at or below 1.5 cm squared — stage D) with favourable valve morphology, less than moderate (2+) MR and no LA thrombus: PMC is a Class 1 recommendation (level A in ACC/AHA 2020; Class I level B in ESC 2021), performed at a Comprehensive Valve Centre. In asymptomatic severe MS with the same favourable anatomy, PMC is Class 2a when resting PASP exceeds 50 mmHg and Class 2b with new-onset AF; ESC adds desire for pregnancy and major non-cardiac surgery as triggers. When MVA is above 1.5 cm squared and symptoms are otherwise unexplained, PMC may be considered if exercise raises the mean gradient above 15 mmHg (or the wedge pressure above 25 mmHg).^[1][7][19]

Step 1 — Medical optimisation (every patient)

• Rate control — oral metoprolol 50 to 100 mg daily: in a placebo-controlled randomised trial in isolated MS in sinus rhythm, six months of metoprolol at this dose held the resting and exercise mean wedge pressure almost flat (rise of 2.5 and fall of 4.6 mmHg) where placebo rose by 9.1 and 16.4 mmHg (p under 0.01), with better symptomatic improvement. Rate control is Class 2a in AF with a rapid ventricular response and in symptomatic sinus tachycardia, but routine beta-blockade in sinus rhythm without tachycardia risks chronotropic incompetence. Add digoxin if rate control is incomplete in AF.^[15][1]
• Diuretic for symptomatic congestion — an oral loop diuretic, titrated to weight and congestion status.^[1]
• Oral anticoagulation — a vitamin K antagonist is indicated (Class 1) in rheumatic MS with AF, a prior embolic event or LA thrombus, target INR 2 to 3; DOACs are NOT recommended in moderate-to-severe MS or with mechanical valves, and INVICTUS (4,531 patients with rheumatic-heart-disease AF) found vitamin K antagonist therapy better than rivaroxaban — fewer strokes and lower mortality without more major bleeding. This is valvular AF.^{[1][7][22][28][10]}
• Secondary rheumatic prophylaxis — benzathine penicillin G 1.2 million units IM every 3 to 4 weeks (600,000 units for a child of 25 to 27 kg or less), for at least 10 years, with lifelong prophylaxis in high-risk patients according to valve-disease severity and streptococcal exposure; high-endemicity programmes shorten the interval to every 15 to 21 days, and sulfadiazine 1 g daily (500 mg under 25 kg) is the alternative in penicillin allergy.^{[7][23][29][14]}
• Lifestyle and triggers — avoid strenuous exertion if symptomatic; treat fever, anaemia, hyperthyroidism aggressively, as each raises the gradient.^[1]

Step 2 — Percutaneous mitral commissurotomy (PMC) — the treatment of choice when anatomy is favourable

• Eligibility: symptomatic severe MS with favourable valve anatomy (pliable, non-calcified leaflets, no LA or LAA thrombus, less than moderate (2+) MR, Wilkins at or below 8, Cormier 1 or 2); ESC lists MVA above 1.5 cm squared, LA thrombus, more than mild MR, severe or bi-commissural calcification, absent commissural fusion, severe concomitant aortic or tricuspid disease needing surgery, and coronary disease needing bypass as contraindications.^[7][1]
• Technique — Inoue balloon PMC: transseptal puncture (now routinely echo-guided, with anticoagulation given before crossing the septum), then an Inoue balloon catheter advanced across the mitral valve and inflated, splitting the fused commissures by mechanical force.^[21][1]
• Evidence: Reyes (NEJM 1994) randomised 60 patients with severe MS and favourable anatomy to balloon valvuloplasty versus open surgical commissurotomy — valve area rose from 0.9 to 2.1 cm squared with the balloon and 0.9 to 2.0 cm squared with surgery, and at three years the balloon group had the larger area (2.4 versus 1.8 cm squared, p under 0.001) with comparable restenosis, lower cost and no thoracotomy^[4]. Ben Farhat (Circulation 1998) randomised 90 patients to balloon, closed and open commissurotomy: residual MS (MVA under 1.5 cm squared) was 0 percent after balloon or open commissurotomy versus 27 percent after closed commissurotomy, with balloon and open commissurotomy equivalent through 7 years of follow-up^[3]. Balloon commissurotomy is now the preferred option for favourable anatomy where the expertise is available.^[3][4]
• Procedural risks: severe MR from leaflet tear — 6.7 percent severe and 11.9 percent moderate in a series of 342 patients; a residual iatrogenic atrial septal defect (about 5 mm, usually closing within 6 months); cardiac tamponade, historically around 4 percent and lower with echo-guided transseptal puncture; embolism and stroke; restenosis — freedom from restenosis was 85, 70 and 44 percent at 5, 10 and 15 years in a cohort of mean age 31.^[21]
• Post-procedure care: bedrest, anticoagulation, telemetry for tamponade; lifelong warfarin if AF or LA thrombus; continue benzathine penicillin prophylaxis.^[1][5]

Step 3 — Mitral valve replacement (MVR) when PMC is contraindicated or unfavourable

• Indications: severe MS with unfavourable anatomy (calcified rigid leaflets, Cormier 3, Wilkins above 8, significant MR, LA thrombus despite anticoagulation), restenosis after PMC, or symptom recurrence after failed intervention.^[1][2][7]
• Options: a mechanical prosthesis — lifelong vitamin K antagonist to an INR target of 3.0 (range 2.5 to 3.5) for a mitral prosthesis, and reasonable to prefer under 65 years of age when anticoagulation is not contraindicated and repair is impossible — or a bioprosthetic valve (no lifelong VKA but structural deterioration over time; reasonable to prefer at 65 years or older, or whenever anticoagulation is contraindicated).^[1][7]
• Surgical risk — individualised to comorbidity, pulmonary pressures and centre experience; intra-operative transoesophageal echo guides repair versus replacement.^[2]

Step 4 — Adjunctive: anticoagulation, prophylaxis, surveillance

• Warfarin in MS plus AF, prior embolism or LA thrombus — INR 2.0 to 3.0.^[1][10][11]
• Endocarditis prophylaxis is not indicated for native-valve MS; antibiotic prophylaxis for high-risk dental procedures is reserved for patients with prosthetic valves (including transcatheter valves), repairs using prosthetic material, or previous infective endocarditis.^[7]
• Surveillance — clinical review 6 to 12 monthly; TTE 1 to 3 yearly for stable disease, sooner if symptoms or PASP rise.^[1][2]

^{[1] [2] [3] [4] [7]}

Special situations you will actually meet

• MS in pregnancy — the rising cardiac output and heart rate of pregnancy decompensate MS in women who were previously asymptomatic; mitral stenosis is the commonest significant valve lesion in pregnant women in endemic regions, and an MVA under 1.5 cm squared is usually poorly tolerated. Beta-blockers are the cornerstone (metoprolol 50 to 100 mg daily), with a loop diuretic as needed for congestion. PMC should be considered for NYHA class III to IV symptoms or a systolic pulmonary pressure above 50 mmHg despite optimal therapy, preferably after the 20th week and in an experienced centre; in 70 pregnant Indian women with critical MS it succeeded in 97 percent at a mean gestation of 29.5 weeks, with significant improvement in NYHA class, valve area and gradient. Deliver at a centre with cardiac surgical backup — maternal and fetal mortality with mitral valve surgery in pregnancy is 20 percent or more.^{[7][18][17][21]}
• New atrial fibrillation in severe MS — the highest-risk group for acute decompensation. Immediate rate control, heparin anticoagulation, and cardioversion if haemodynamically unstable or symptomatic; exclude LA thrombus by TOE before cardioversion unless AF is reliably under 48 h. Rhythm-control strategies rarely hold before the stenosis is relieved.^[1][7][19]
• Asymptomatic severe MS — surveillance with annual TTE; intervention triggers: symptom onset, resting PASP above 50 mmHg (Class 2a), new-onset AF (Class 2b), desire for pregnancy, or planned major non-cardiac surgery. Randomised trials of early PMC in asymptomatic severe MS did not reduce cardiovascular events overall, though asymptomatic patients with AF or a previous thromboembolic event did benefit.^[1][7][19]
• Calcific or degenerative MS in the elderly — usually unfavourable for PMC (no commissural fusion, heavy calcification); MVR with a bioprosthesis is the standard; transcatheter mitral valve implantation (TMVI) is an emerging option for select patients.^[1][7]
• Mixed mitral disease (MS plus moderate MR) — moderate or worse MR pushes the decision to surgical MVR rather than PMC — the balloon would worsen MR by tearing leaflets; PMC is not appropriate.^[1][7]
• Restenosis after PMC — re-intervention depends on anatomy; re-PMC if the valve is still favourable at repeat Wilkins assessment, otherwise MVR.^[1][2]
• Mechanical mitral prosthesis during pregnancy — the highest valve-related pregnancy risk (warfarin teratogenicity in the first trimester; maternal thromboembolism in any trimester). Anticoagulation through pregnancy needs specialist obstetric-cardiology supervision: warfarin carries fetal risk early, heparin-based regimens carry maternal valve-thrombosis risk, and the balance shifts by trimester. Plan delivery with a peri-delivery switch to unfractionated heparin.^[1][2][7]

How patients with mitral stenosis come to harm (the preventable list)

• Treating MS pulmonary oedema with vasodilators or nitrates first-line — the LV is preload-dependent; rate control and careful diuresis are the answer.^[1][2]
• Prescribing a DOAC in MS plus AF — moderate-to-severe MS was excluded from the DOAC trials, and INVICTUS found a vitamin K antagonist better than rivaroxaban; VKA only.^[22][10][7]
• Failing to anticoagulate MS with AF — embolic stroke in a young patient is the high-yield disaster scenario; a vitamin K antagonist is Class 1 with AF, prior embolism or LA thrombus.^[1][25]
• Offering PMC to an unfavourable valve (calcified, high Wilkins, with LA thrombus or significant MR) — a fruitless balloon and increased procedural risk.^[1][7]
• Treating the murmur, not the valve area — a soft murmur may accompany very severe MS if the valve is heavily calcified with low flow; severity is graded by valve area, mean gradient, pressure half-time and PASP.^[1][19]
• Missing pregnancy in a young asymptomatic MS patient — counsel early; intervene before pregnancy if MVA is approaching 1.5 cm squared.^[1][7]
• Forgetting secondary prophylaxis — benzathine penicillin G 1.2 million units IM every 3 to 4 weeks prevents recurrent ARF; register the patient.^[7][29][14]

Prognosis and disposition

The natural history of untreated MS is unfavourable once symptoms develop. Twenty-year survival is excellent while patients remain asymptomatic, but about half deteriorate abruptly with AF or systemic embolism; in degenerative (calcific) MS, driven by age and comorbidity, 5-year survival is under 50 percent.^[19][21]

With PMC: event-free survival in a developing-country cohort with favourable anatomy was 89 percent at 5 years, 79 percent at 10 years and 43 percent at 15 years; older patients with less favourable anatomy in industrialised countries did worse (56 percent event-free at 10 years). Repeat PMC remains reasonable when restenosis is due to commissural refusion and the anatomy is still favourable.^[21][7]

With MVR: prosthetic valve survival is excellent, but lifelong anticoagulation risk (mechanical) or structural deterioration risk (bioprosthetic) frames long-term outcomes.^[1][7]

Predictors of poor prognosis: older age at presentation, atrial fibrillation, severe pulmonary hypertension (PASP above 60 mmHg), a heavily calcified valve, a high Wilkins score, comorbidities limiting intervention, and lack of access to benzathine penicillin prophylaxis with recurrent ARF.^[1][2][5][9]

Disposition:^[1]

• Asymptomatic mild or moderate MS — outpatient follow-up with serial echo every 1 to 3 years; lifestyle advice (avoid dehydration, treat AF onset promptly).^[1]
• Symptomatic severe MS — refer to a structural heart or valve centre for anatomy assessment and the PMC or MVR decision; anticoagulate and titrate rate control in the meantime.^[1][7]
• Acute pulmonary oedema with AF — emergency admission to a monitored bed; HDU or CCU for oxygen, IV diuretic and rate control; structural heart team notification.^[1][2]

Pregnancy and special populations

• Pregnancy — the increasing volume load and heart rate decompensate previously silent MS; beta-blockers (metoprolol 50 to 100 mg daily), a diuretic as needed, and PTMC for severe refractory symptoms; warfarin is teratogenic (avoid in the first trimester for a valve indication); mechanical prostheses need specialist-supervised anticoagulation that changes by trimester; a multidisciplinary team (cardiologist, obstetrician, anaesthetist, neonatologist) for delivery and the puerperium.^{[15][17][18][1][7]}
• Paediatric or adolescent — usually congenital (parachute mitral valve, Shone complex) or early rheumatic; surgical repair is preferred for paediatric anatomy; percutaneous options are reserved for older children with rheumatic anatomy.^[1]
• Elderly (calcific MS) — unfavourable anatomy for PMC; bioprosthetic MVR or TMVI for high-risk surgical candidates; medical management with rate control, diuretic and judicious anticoagulation is the realistic bridge.^[1][7]
• Exercise and sport — exercise haemodynamics matter more than resting numbers: a mean gradient above 15 mmHg or a wedge pressure above 25 mmHg on exercise marks haemodynamically significant disease and supports intervention, and symptoms or a resting PASP above 50 mmHg define the high-risk group. Clearance for competitive sport in clinically significant MS needs specialist assessment, with exercise testing as the tool.^[1][7]
• MS with AF — a vitamin K antagonist lifelong (DOACs are not an option in moderate-to-severe MS), rate control with a beta-blocker plus digoxin as needed, address the valve (PMC or MVR if appropriate).^[1][22][28]
• MS with a mechanical prosthesis — lifelong vitamin K antagonist to an INR target of 3.0 (range 2.5 to 3.5) for a mitral prosthesis; warfarin carries first-trimester fetal risk, so pregnancy needs planned, specialist-supervised anticoagulation; consider INR self-monitoring; antibiotic prophylaxis for high-risk dental procedures applies once a prosthesis is in place.^[1][7]
• Indigenous or low-income populations — system-level prevention: improve housing, address overcrowding, treat streptococcal pharyngitis with penicillin, deliver benzathine penicillin G 1.2 million units IM every 3 to 4 weeks to ARF and RHD patients, and train community health workers in screening echo.^[7][9][29]

Evidence, guidelines and regional differences

Key guidelines:^[1]

• 2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease (Otto CM et al., Circulation 2021) — the contemporary US standard; Class 1 (level A) for PMC in symptomatic (NYHA II to IV) severe MS with favourable morphology, less than moderate (2+) MR and no LA thrombus; a vitamin K antagonist (not a DOAC) for rheumatic MS with AF.^[1]
• 2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease (Nishimura RA et al., Circulation 2014) — the historical foundation for severity grading and PMC indications; Wilkins scoring recommended for anatomy assessment.^[2]
• 2021 ESC/EACTS Guidelines for the Management of Valvular Heart Disease (Vahanian A et al., Eur Heart J 2022) — the European standard, aligning with ACC/AHA on severity grading and PMC; emphasising heart-team decision-making for borderline anatomy.^[7]
• 2015 AHA Revision of the Jones Criteria (Gewitz MH et al., Circulation 2015) — the basis for ARF diagnosis, adding Doppler echocardiography for subclinical carditis and separate criteria for high-risk populations.^[5]

Landmark trials every candidate must know:^[1]

• Reyes (NEJM 1994) — randomised 60 patients to PMC versus open surgical commissurotomy: comparable initial results, a larger valve area with the balloon at 3 years (2.4 versus 1.8 cm squared), lower cost and no thoracotomy.^[4]
• Ben Farhat (Circulation 1998) — randomised 90 patients to balloon, closed surgical and open surgical commissurotomy with 7-year follow-up: balloon and open commissurotomy were equivalent; closed was inferior (27 percent residual stenosis).^[3]
• Wilkins score (Br Heart J 1988) — the score that predicts PMC outcome; at or below 8 is favourable for PMC.^[8]
• Marijon (Lancet 2012) — a comprehensive review of the global burden, pathophysiology and prevention of rheumatic heart disease (about 250,000 deaths a year worldwide) that frames the preventive and public-health approach.^[9]
• INVICTUS (NEJM 2022) — 4,531 patients with rheumatic-heart-disease AF randomised to rivaroxaban or a dose-adjusted vitamin K antagonist: the VKA arm did better (restricted mean survival 1,675 versus 1,599 days; more deaths with rivaroxaban), which is why VKA remains the standard of care in moderate-to-severe MS with AF. Owens (Clin Cardiol 2017) documents the exclusion of rheumatic MS from the DOAC trials.^[22][28][10]

Current controversies: (1) whether any DOAC can replace a vitamin K antagonist in rheumatic MS with AF — INVICTUS says no, while smaller studies (RIVER in bioprosthetic mitral valves, the 40-patient RISE-MS) were neutral^[22][28]; (2) whether moderate-to-severe MS is truly an independent stroke risk factor, since CHA2DS2-VASc performed only modestly in rheumatic AF^[28]; (3) early PMC in asymptomatic severe MS, where randomised trials showed no overall event reduction^[19][7]; (4) transcatheter mitral valve implantation for high-risk surgical candidates with degenerative MS^[7][21]; (5) whether anticoagulation is justified in sinus rhythm on the basis of a very large LA or dense spontaneous echo contrast alone.^[1][19]

The mantra, and the viva honesty line

^[1]

The mantra: loud S1, opening snap, diastolic rumble — rate-control the decompensation, warfarin the AF, and split the commissures if the valve is pliable.^[1][2][10]

Ward-round test — three stems, thirty seconds each

Stem 1 — the pregnant woman from the top of the topic (answer)ShowHide

A 28-year-old, 26 weeks pregnant, wakes with acute pulmonary oedema and a fast irregular pulse; mitral facies, loud S1, opening snap, mid-diastolic rumble at the apex. What is the diagnosis, and what is the FIRST drug to reach for — and the drug to avoid? Model: Previously silent rheumatic mitral stenosis, decompensated by the gestational volume load and new atrial fibrillation. The first lever is rate control — IV metoprolol lengthens diastole and drops the transmitral gradient — alongside an IV loop diuretic and oxygen. Anticoagulate with weight-based heparin (AF plus likely LA stasis). Avoid vasodilators and nitrates: the LV is preload-dependent behind a fixed obstruction and will collapse. Confirm with TTE, exclude LAA thrombus with TOE before any cardioversion, and plan PTMC during pregnancy if severe symptomatic MS is refractory to medical therapy.^{[16][12][17][18][1]}

Stem 2 — the young stroke and the silent valve (answer)ShowHide

A 34-year-old man presents with a middle cerebral artery infarct. He is in AF. An echocardiogram shows MVA 1.1 cm squared, a pliable non-calcified valve, and no LA thrombus. What is the diagnosis, the anticoagulation, and the definitive plan? Model: Silent rheumatic mitral stenosis presenting with embolic stroke from AF. This is valvular AF — anticoagulate with warfarin (NOT a DOAC: moderate-to-severe MS and mechanical valves were excluded from the DOAC trials, so only warfarin has evidence here). Once recovered, the valve anatomy is favourable for PMC (Wilkins likely at or below 8, pliable, no thrombus), so refer for percutaneous mitral commissurotomy — equivalent to open commissurotomy at 7 years (Ben Farhat) with lower cost and faster recovery (Reyes). Continue benzathine penicillin G 1.2 million units IM every 4 weeks for secondary prophylaxis.^{[1][3][4][10][14]}

Stem 3 — the elderly man with a calcified valve (answer)ShowHide

A 72-year-old with diabetes and CKD has exertional dyspnoea; echo shows MVA 1.0 cm squared, a heavily calcified valve with restricted leaflets, moderate MR, and PASP 55 mmHg. Why is PMC the wrong answer, and what is right? Model: This is calcific or degenerative MS with unfavourable anatomy — Cormier 3, Wilkins above 8, and moderate MR. PMC is contraindicated: there is no commissural fusion to split, and the balloon would worsen the MR by tearing calcified leaflets. The right answer is mitral valve replacement (a bioprosthesis, given his age and CKD), or — if surgical risk is prohibitive — medical management with rate control, diuretic and judicious anticoagulation, with transcatheter mitral valve implantation (TMVI) in a selected centre. Do not offer a balloon to a valve it cannot help.^[1][7]

References29ShowHide

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