Mitral Valve Prolapse

Mitral valve prolapse (MVP), also known as floppy mitral valve syndrome, is a valvular heart disease characterised by the displacement of an abnormally thickened mitral valve leaflet into the left atrium during systole. It can be classified broadly as classic and nonclassic, with the primary diagnostic tool being echocardiography.

Signs and Symptoms

The hallmark of MVP is a mid-systolic click followed by a late systolic murmur heard best at the apex, which can be accentuated by standing and Valsalva manoeuvre and diminished with squatting. Symptoms may include palpitations, atypical chest pain, dyspnea on exertion, and signs of autonomic nervous system dysfunction such as lightheadedness and headaches.

Complications

Severe cases of classic MVP may lead to complications such as mitral regurgitation, infective endocarditis, congestive heart failure, and, in rare cases, cardiac arrest. Mitral regurgitation, where blood flows abnormally from the left ventricle back into the left atrium, is frequently associated with MVP and can be graded on a scale from 0 (none) to 4 (severe).

Risk Factors

Risk factors for MVP include connective tissue disorders like Ehlers-Danlos syndrome, Marfan syndrome, polycystic kidney disease, and Graves' disease. Individuals with MVP often have a low BMI and are typically leaner than those without the condition. Rheumatic fever, a significant cause of damaged heart valves worldwide, can also contribute to MVP.

Diagnosis

Echocardiography remains the gold standard for diagnosing MVP, allowing for visualisation of mitral leaflets relative to the mitral annulus and measurement of leaflet thickness and displacement. MVP is classified into several subtypes, including classic, nonclassic, symmetric, asymmetric, flail, or non-flail based on leaflet thickness, connection to the mitral annulus, and concavity.

Treatment

Many individuals with MVP, especially those without symptoms, require no treatment. Symptomatic patients may benefit from beta-blockers. In cases of severe mitral regurgitation, surgical repair or replacement of the mitral valve may be necessary, with repair being generally preferred over replacement. Blood thinners may be required for those with prior stroke or atrial fibrillation.

Prevention of Infective Endocarditis

Individuals with MVP are at higher risk for infective endocarditis, a bacterial infection of the heart tissue. While prophylactic antibiotics were previously recommended before invasive procedures, current guidelines suggest this only for patients with the highest risk of adverse outcomes.

Prognosis

Generally, MVP is benign. However, patients with a murmur, as opposed to an isolated click, show increased mortality rates. Regular monitoring and treatment of complications are essential to reduce risks.

Epidemiology

MVP affects approximately 2-3% of the population. Studies like the Framingham Heart Study and the Taiwanese CHIEF heart study have provided estimates of its prevalence. MVP is observed in about 7% of autopsies in the United States and is more prevalent in those with a lower BMI and certain somatic symptoms.

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Self-assessment MCQs (single best answer)

What is the primary diagnostic tool for Mitral Valve Prolapse (MVP)?

Which of the following is a hallmark auscultation finding in MVP?

Which manoeuvre can accentuate the murmur of MVP?

What is a common complication of severe classic MVP?

Which connective tissue disorder is a risk factor for MVP?

In the context of MVP, what does the term "flail" describe?

What is the treatment of choice for severe mitral regurgitation associated with MVP?

Which of the following best describes the epidemiology of MVP?

What staining method is used to demonstrate thickening of the spongiosa layer in myxomatous degeneration?

Which of the following is NOT a typical symptom of MVP?