Mitral Valve Prolapse

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”).
• Synonym(s): systolic click-murmur syndrome, billowing mitral cusp syndrome, myxomatous mitral valve, floppy valve syndrome, redundant cusp syndrome, Barlow syndrome.

Epidemiology

Prevalence

• Estimated 1–3% of the population (1),(2)
• Equally distributed by gender (1),(2)
• Typically found in adults, although not at a certain stage of adulthood (1),(2)

Etiology and Pathophysiology

• The pathophysiology of MVP typically involves myxomatous degeneration of the mitral valve leaflets, characterized by expansion of the valve spongiosa layer, structural alterations in collagen, and structurally abnormal chordae (1),(3).
• 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):
  • Primary MVP: sporadic or familial
  • Secondary MVP
    • “Syndromic” MVP: myxomatous degeneration associated with connective tissue disorders, for example 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

• In primary MVP, both autosomal dominant and X-linked instances have been found.
  • Autosomal dominant: variable penetrance; several genetic loci so far identified (1)
    • MMVP1: chromosome 16 p11.2–p12.1
    • MMVP2: chromosome 11 p15.4
    • MMVP3: chromosome 13 q31.3–q32.1
  • X-linked: One gene has been identified: filamin A gene, Xq28 (1).
• Connective tissue disorders, which often have a genetic basis, are associated with secondary MVP (see “Etiology and Pathophysiology”).

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.”)
• MVP is more common with leaner BMI (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.”)
• MVP is implicated in the development of other medical conditions/complications, such as MR and stroke. (See “Complications.”)
• Some associated conditions that are less clearly either (i) a cause of MVP or (ii) caused by MVP include von Willebrand disease; primary hypomastia; thoracic skeletal abnormalities; and prolapse of the tricuspid, pulmonic, or aortic valves.