Occurs when blood leaks back through the mitral valve during systole

Aetiology

• Most common cause is rheumatic heart disease
• Rarer causes are seen in developed countries and include:
  • Mitral annular calcification (age-related)
  • Infective endocarditis
  • MI causing valve prolapse
  • Secondary to left ventricular dysfunction e.g. from cardiomyopathy, or post-MI
  • Congenital mitral stenosis (rare)
  • Mucopolysaccharidosis (metabolic disorder affecting connective tissue)
  • Carcinoid syndrome, causing valve disease
  • Systemic disease, including systemic lupus erythematosus (SLE) and rheumatoid arthritis
• Depending on aetiology MR can present acutely or chronically

Clinical presentation

Acute MR

Acute mitral regurgitation is usually a cardiac emergency and presents with sudden onset symptoms of:

• Shortness of breath
• Exertional dyspnoea
• Fatigue
• Weakness

Chronic MR

With chronic mitral regurgitation, the symptoms are associated with the degree of impairment:

• Patients with mild to moderate MR may be asymptomatic until there is significant systolic dysfunction, pulmonary hypertension or symptomatic atrial fibrillation (AF)
• Fatigue and exertional dyspnoea are most common, a result of decreased cardiac output as well as increased pulmonary pressures due to increased left atrial pressures

Signs

• Pan-systolic murmur best heard at the apex (5th intercostal space in the left midclavicular line)
• Murmur radiates to the axilla
• Displaced apex