Mitral valve disease encompasses two primary pathological conditions of the left atrioventricular valve: mitral stenosis (MS) and mitral regurgitation (MR), which often coexist. MS is characterized by narrowing of the mitral valve orifice, impairing left ventricular filling and elevating left atrial pressure. MR is characterized by incomplete leaflet closure, causing retrograde systolic blood flow from the left ventricle to the left atrium, leading to left ventricular volume overload and eventual heart failure.

• Etiology:
  • Mitral Stenosis: Over 90% of global cases are caused by rheumatic heart disease (RHD), from post-rheumatic fever scarring, thickening, and commissural fusion of valve leaflets and chordae. Rare causes include congenital stenosis, degenerative calcific MS, and carcinoid syndrome.
  • Mitral Regurgitation: Classified into primary (organic) MR (structural valve abnormalities: myxomatous degeneration/mitral valve prolapse, RHD, infective endocarditis, chordal rupture) and secondary (functional) MR (left ventricular dilation/dysfunction from ischemic heart disease or cardiomyopathy).
• Clinical Manifestations:
  • MS: Early symptoms include exertional dyspnea, palpitations, and fatigue. Advanced disease presents with orthopnea, paroxysmal nocturnal dyspnea, hemoptysis, atrial fibrillation (present in ~50% of patients), right heart failure, and thromboembolic stroke. Severe MS is defined as mitral valve area <1.0 cm².
  • MR: Acute MR (chordal rupture, papillary muscle infarction) presents with sudden severe dyspnea, pulmonary edema, and cardiogenic shock. Chronic MR is asymptomatic for decades, with progressive exertional dyspnea, fatigue, palpitations, and eventual left ventricular dysfunction and heart failure.
• Diagnosis: TTE is the first-line gold standard, assessing valve morphology, stenosis/regurgitation severity, left atrial size, left ventricular function, and pulmonary pressure. TEE is used for pre-procedural planning for transcatheter intervention and surgical repair.

• Mitral Stenosis Management:
  • Conservative Management: For asymptomatic mild-moderate MS, with serial surveillance, diuretics for symptom control, heart rate control for AF, and lifelong anticoagulation for AF or prior thromboembolism. Rheumatic fever prophylaxis is mandatory for all rheumatic MS patients.
  • Percutaneous Mitral Balloon Commissurotomy (PMBC): First-line treatment for symptomatic severe rheumatic MS with favorable valve morphology, a minimally invasive transseptal procedure with a >95% procedural success rate.
  • Surgical Treatment: Indicated for severe MS unsuitable for PMBC, severe MS with moderate-severe MR, or left atrial thrombus despite anticoagulation. Procedures include mitral valve repair (select cases) and mitral valve replacement (MVR).
• Mitral Regurgitation Management:
  • Conservative Management: For asymptomatic mild-moderate MR with preserved left ventricular function, with serial surveillance, guideline-directed medical therapy (GDMT) for underlying heart failure/ischemia.
  • Surgical Treatment: Gold standard for severe primary MR, with mitral valve repair (MVRp) strongly preferred over replacement for superior long-term survival and left ventricular preservation. Minimally invasive surgery is widely used.
  • Transcatheter Mitral Valve Intervention (TMVI): Minimally invasive procedures for high-risk/inoperable patients. Transcatheter edge-to-edge repair (TEER, MitraClip) is the most established, guideline-recommended for inoperable severe primary MR and selected secondary MR patients.