Description

• Mitral valve prolapse (MVP) is the billowing of one or both mitral valve leaflets into the left atrium (LA) during ventricular systole.
• MVP can be classified in different ways, including by etiology (primary or secondary; see “Etiology and Pathophysiology”) or by morphology (classic MVP and nonclassic MVP; see “Test Interpretation”).
• MVP is often asymptomatic and often has a benign clinical course; however, it may occasionally be associated with symptoms, such as palpitations, or complications, such as mitral regurgitation (MR) (see “Complications”).
• Synonyms include systolic click-murmur syndrome, billowing mitral cusp syndrome, myxomatous mitral valve, floppy valve syndrome, redundant cusp syndrome, Barlow syndrome.

Epidemiology

Prevalence

• The prevalence of MVP is estimated at 2–3% of the general population and is equally distributed by gender and across the age spectrum (1).
• Prior to current echocardiographic criteria, earlier studies estimated the prevalence at 5–15% and indicated a higher prevalence among women and with increased age.

Etiology and Pathophysiology

• The pathophysiology of MVP typically involves myxomatous degeneration of the mitral valve leaflets. Myxomatous degeneration is characterized by expansion of the valve spongiosa layer, structural alterations in collagen, and structurally abnormal chordae (1).
• Papillary muscle or chordae disruption, dysfunction, or rupture may also cause MVP; this can occur without a process causing myxomatous degeneration, or as part of the natural history of a process causing myxomatous degeneration.
• The etiology of MVP is multifactorial and includes the following (1),(2):
  • Primary MVP: sporadic, familial
  • Secondary MVP
    • “Syndromic” MVP: myxomatous degeneration associated with connective tissue disorders: Marfan syndrome, Ehlers-Danlos syndrome, osteogenesis imperfecta, pseudoxanthoma elasticum, Loeys-Dietz syndrome
    • Associated with congenital heart disease: atrial septal defect, Ebstein anomaly
• Papillary/chordae disruption, dysfunction or rupture (infarction, endocarditis, rheumatic fever, trauma, hypertrophic cardiomyopathy)

Genetics

• The genetics of MVP is an active area of research (1),(2).
• In primary MVP, both autosomal dominant and X-linked familial MVP have been identified.
• Autosomal dominant: variable penetrance. Multiple genetic loci have been identified (1).
  • MMVP1 on chromosome 16 p11.2–p12.1
  • MMVP2 on chromosome 11 p15.4
  • MMVP3 on chromosome 13 q31.3–q32.1
• X-linked: One gene has been identified (1): filamin A gene, Xq28.
• Connective tissue disorders, which often have a genetic basis, are associated with secondary MVP (see “Etiology and Pathophysiology” above).

Risk Factors

• Medical conditions implicated in the development of MVP include both heritable and sporadic congenital abnormalities as well as other disease processes (see “Etiology and Pathophysiology” above).
• MVP appears to be more common with a leaner body mass (1).

Commonly Associated Conditions

• Conditions implicated in the development of MVP include both heritable and sporadic congenital abnormalities as well as other disease processes (see “Etiology and Pathophysiology” above).
• MVP is implicated in the development of other medical conditions/complications, such as MR and stroke (see “Complications” below).
• Some associated conditions that are less clearly either (i) a cause of MVP or (ii) caused by MVP include (3) von Willebrand disease; primary hypomastia; thoracic skeletal abnormalities; prolapse of the tricuspid, pulmonic, or aortic valves.