Cardiology > Mitral Stenosis

Background

Mitral stenosis (MS) is a narrowing of the mitral valve orifice that impedes blood flow from the left atrium to the left ventricle during diastole. This obstruction results in increased left atrial pressure, pulmonary venous congestion, and ultimately right heart strain. Over time, it can lead to atrial fibrillation, thromboembolic events, pulmonary hypertension, and right-sided heart failure. 

II) Classification or Types

By Etiology: 

• Rheumatic Mitral Stenosis: Most common; characterized by leaflet thickening, commissural fusion, and chordal shortening. 

• Congenital Mitral Stenosis: Rare; includes parachute mitral valve or supravalvular mitral ring. 

• Degenerative/Calcific MS: Seen in elderly; primarily involves annular calcification. 

• Radiation-induced MS: Occurs years after chest radiation. 

By Severity (based on mitral valve area on echo): 

• Mild: >1.5 cm² 

• Moderate: 1.0–1.5 cm² 

• Severe: <1.0 cm² 

III) Epidemiology 

• Sex: More common in females (2:1 ratio). 

• Age: Rheumatic MS typically manifests decades after initial infection (30–50 years old). 

• Region: High prevalence in developing countries due to untreated streptococcal infections. 

• Socioeconomic Status: Higher in lower-income populations with limited healthcare access and rheumatic fever prevention. 

Etiology

I) What Causes It

• Rheumatic heart disease (most common globally) 

• Congenital valve malformations 

• Mitral annular calcification (elderly) 

• Infective endocarditis with fibrosis 

• Chest radiation therapy (late complication) 

• Rarely: systemic diseases (e.g., lupus, carcinoid syndrome) 

II) Risk Factors

• History of rheumatic fever 

• Recurrent streptococcal pharyngitis 

• Untreated bacterial infections in childhood 

• Female sex 

• Living in endemic regions 

• History of chest irradiation 

Clinical Presentation

I) History (Symptoms)

• Progressive exertional dyspnea 

• Orthopnea and paroxysmal nocturnal dyspnea (PND) 

• Hemoptysis (due to pulmonary venous hypertension or rupture) 

• Fatigue and decreased exercise tolerance 

• Palpitations (often due to atrial fibrillation) 

• Thromboembolic events (e.g., stroke) 

• In pregnancy: marked worsening due to increased blood volume 

II) Physical Exam (Signs)

Vital Signs: 

• Irregularly irregular pulse (atrial fibrillation) 

• Possible signs of low cardiac output in advanced stages 

Cardiac Exam: 

• Opening snap after S2, best heard at apex 

• Low-pitched diastolic rumbling murmur best at apex with bell in left lateral decubitus position 

• Loud S1 (if valve still pliable) 

• Signs of pulmonary hypertension (loud P2, right ventricular heave) 

Pulmonary: 

• Crackles (from pulmonary edema) 

• Wheezing (“cardiac asthma”) 

Peripheral: 

• Peripheral edema (late finding) 

• Elevated jugular venous pressure (with right heart failure) 

• Ascites (in advanced cases) 

Differential Diagnosis (DDx)

• Pulmonary hypertension (primary or secondary) 

• Mitral regurgitation 

• Atrial myxoma 

• Constrictive pericarditis 

• Heart failure with preserved ejection fraction (HFpEF) 

• Tricuspid stenosis 

• COPD/asthma 

• Pulmonary embolism 

Diagnostic Tests

Initial Tests: 

• Echocardiography (TTE): 

• Valve area estimation 

• Mean gradient >5 mmHg suggests significant MS 

• Left atrial enlargement, pulmonary pressures 

• Presence of thrombus (with TEE) 

• Electrocardiogram (ECG): 

• Atrial fibrillation 

• Left atrial enlargement (P mitrale) 

• Chest X-ray: 

• Left atrial enlargement (straightened left heart border) 

• Pulmonary venous congestion 

• Kerley B lines 

• BNP/NT-proBNP: 

• May be elevated with heart failure symptoms 

• Cardiac MRI/CT: 

• When echo is inconclusive or for surgical planning 

• Cardiac catheterization: 

• To measure pulmonary artery pressure and confirm severity 

• Required pre-op to assess coronary anatomy if surgery planned 

Basic Lab 

Treatment

I) Medical Management:

• Symptom relief: 

• Diuretics for pulmonary congestion 

• Beta-blockers or nondihydropyridine calcium channel blockers for heart rate control 

• Digoxin in atrial fibrillation 

• Anticoagulation: 

• All patients with MS and atrial fibrillation (warfarin preferred) 

• Consider in large left atrium (>55 mm) or left atrial thrombus 

• Infective endocarditis prophylaxis: 

• Not routinely recommended unless prior endocarditis or prosthetic valves 

II) Interventional/Surgical:

• Percutaneous Mitral Balloon Valvotomy (PMBV): 

• First-line for symptomatic severe rheumatic MS with favorable valve morphology (Wilkins score ≤8) 

• Contraindicated with left atrial thrombus or moderate/severe MR 

• Mitral Valve Replacement (MVR): 

• For non-pliable valves, presence of MR, or when PMBV is contraindicated 

• Surgical Repair (rare): 

• Only feasible in select congenital cases 

Patient Education, Screening, Vaccines

• Emphasize medication adherence 

• Teach signs of worsening heart failure or atrial fibrillation 

• Daily weight monitoring for fluid retention 

• Avoid exertion in severe cases until evaluated 

• Dental hygiene to prevent endocarditis 

Vaccines: 

• Annual influenza, pneumococcal, and COVID-19 vaccines 

Consults/Referrals

• Cardiology: All moderate to severe cases 

• Interventional cardiology: For consideration of PMBV 

• Cardiothoracic surgery: For MVR 

• Infectious disease: If endocarditis suspected 

• Obstetrics (high-risk): In pregnant women with MS 

• Neurology: If stroke or TIA from embolism 

Follow-Up

• Regular echocardiograms (every 1–2 years if moderate/severe) 

• Monitor for development of atrial fibrillation and thromboembolic complications 

• Optimize rate control and anticoagulation 

• Reassess candidacy for intervention if symptoms progress 

• Monitor functional status and quality of life