Mitral valve prolapse

Mitral valve prolapse (MVP) is caused by a structural defect of the mitral valve that results in mitral leaflets bulging into the left atrium during systole. In the US, MVP is the most common heart valve abnormality and the most common cause of mitral regurgitation (MR). Although MVP is typically asymptomatic, symptoms (eg., palpitations, fatigue, dyspnea) may arise, especially if associated with MR. A mitral prolapse click is a classic auscultatory finding MVP and diagnosis is made with echocardiography. No specific treatment is needed unless severe, symptomatic MR is present, in which case mitral valve repair or replacement is required.

• Prevalence: 2–3 % (one of the most common valvular abnormalities in the US)
• The most common cause of mitral regurgitation in developed countries

References:^[1][2]

Epidemiological data refers to the US, unless otherwise specified.

• Mostly idiopathic
• Connective tissue disorders: Marfan syndrome, Ehlers-Danlos syndrome, osteogenesis imperfecta
• Fragile X syndrome ^[3]
• Myocardial infarction: infarction of papillary muscles → rupture of chordae tendineae → mitral valve prolapse
• Acute rheumatic heart disease
• Infective endocarditis
• Autosomal dominant polycystic kidney disease

References:^[4]

• The most common underlying pathology in the case of mitral valve prolapse is myxomatous degeneration (deposition of glycosaminoglycan such as dermatan sulfate) of the mitral valve due to a primary disease or connective tissue disorder
  • Long, floppy mitral valve leaflets with excessive valvular tissue → the mitral annulus becomes dilated and the chordae tendineae become elongated (and may rupture) → prolapse of one or both mitral valve leaflets into the left atrium during systole
  • The leaflets may also exhibit fibrous thickening at regions where they rub against each other.
• Mitral valve prolapse sets into motion a vicious cycle of events.
  • If prolapse happens without the rupture of chordae tendineae → mitral valve leaflets billow into the left atrium → mild to moderate mitral regurgitation
  • If the papillary muscles become severely ischemic and the chordae tendineae rupture → mitral valve leaflets flail about in the left atrium → severe mitral regurgitation

References:^[4]

• Most patients are asymptomatic.
• Rarely: atypical chest pain and anxiety
• In case of complications: fatigue, dyspnea, cough, syncope, and palpitations (see “Complications” below)
• Auscultatory findings
  • Mitral valve prolapse click: high-frequency, midsystolic click that is best heard at the mitral region
  • High-frequency, mid-to-late systolic murmur that is best heard at the mitral region and may radiate to the axilla (squatting diminishes the murmur)
  • Patients with severe MR: S3 may be heard as a result of left ventricular overload (especially in the left decubitus position)

References:^[4]

• ECG: mostly normal
• Transthoracic echocardiography (test of choice) to confirm diagnosis
  • Echocardiographic definition of MVP: displacement of the mitral valve during systole by more than 2 mm above the mitral valve annulus in the parasternal long-axis view
    • Classical MVP (∼ 60%): leaflet thickness ≥ 5 mm
    • Non-classical MVP (∼ 40%): leaflet thickness < 5 mm
• Transesophageal echocardiography (TEE) is used as an adjunct to TTE and intraoperatively to guide mitral valve repair procedures.

References:^[4]

• No treatment is required in most cases.
• Patients with severe mitral regurgitation : mitral valve repair or replacement (see “Therapy” in “Mitral regurgitation”)
• Additional treatment is required when complications arise (see “Complications” below)

References:^[4]

• Atrial fibrillation
• Ventricular ectopics : MVP patients with ventricular ectopics should be asked to avoid caffeine; β-blockers may be used for symptomatic relief.
• Transient ischemic attacks (TIA) and/or stroke : Patients who experience TIA or stroke will require prophylactic doses of aspirin (also see “Therapy” in stroke)
• Infective endocarditis : MVP patients with a past history of infective endocarditis require prophylaxis against infective endocarditis (see prophylaxis for endocarditis).
• Right heart failure
• Sudden cardiac death (rare)

References:^[5][6][7]

We list the most important complications. The selection is not exhaustive.