Mitral valve prolapse

Mitral valve prolapse

Mitral valve prolapse (MVP) is the systolic billowing of one or both mitral leaflets into the left atrium during systole.It may occur in the setting of myxomatous valve disease or in persons with normal mitral valve leaflets.

Prevalence and Risk Factors

MVP is the most common valvular disorder in the United States, occurring in 2.4% of the general population. There is a similar prevalence in men and women, with a greater risk of complications in men.

Pathophysiology and Natural History

Many patients with MVP have normal mitral leaflets, with little or no mitral regurgitation, and a benign prognosis. Survival rates among affected patients are similar to those of age- and gender-matched individuals without MVP. In other patients, MVP is caused by myxomatous valve disease, with typical findings of elongated and thickened leaflets, interchordal hooding, and chordal elongation . Patients with myxomatous MVP are at increased risk for cardiovascular complications, particularly when prolapse is associated with at least moderate mitral regurgitation or LV dysfunction. Although most patients with MVP do not develop severe mitral regurgitation, MVP is a common underlying cause of progressive mitral regurgitation, often necessitating mitral valve repair or replacement^.
The causes of myxomatous mitral valve disease are not certain, but appear to involve dysregulation of extracellular matrix proteins. Myxomatous mitral valve disease usually occurs sporadically, although there are well-described cases of familial clustering that involve an autosomal dominant mode of inheritance^. Three genetic loci for autosomal dominant myxomatous mitral valve disease have been described, but the precise genes and mutations have not yet been identified. Myxomatous MVP also may occur in conjunction with certain connective tissue disorders, such as Marfan syndrome and Ehlers-Danlos syndrome.

Signs and Symptoms

Most patients with MVP are asymptomatic. In the past, multiple nonspecific symptoms (atypical chest pain, dyspnea, palpitations, anxiety, and syncope) and clinical findings (low body weight, low blood pressure, and pectus excavatum) were associated with MVP and termed mitral valve prolapse syndrome. Prospective testing has failed to confirm most of these associations. The classic findings of MVP on physical examination are a midsystolic click, with a late systolic murmur, heard best at the cardiac apex.

Diagnosis

Two-dimensional echocardiography is the most important test for diagnosing MVP (Class I).¹ The diagnosis is made when there is displacement of one or both mitral leaflets by 2 mm or more into the left atrium during systole (Fig). Because the mitral annulus is known to have a saddle shape, a normal mitral valve can appear to prolapse in certain echocardiographic views, most notably in the apical two- and four-chamber views. Therefore, the diagnosis of MVP should be based on a long-axis parasternal or apical three-chamber view. In patients with MVP, echocardiography is also useful in determining the presence and severity of MR and assessing left atrial and ventricular chamber size, LV function, and leaflet thickening and redundancy. Unless severe mitral regurgitation is present, findings on the chest radiograph and ECG typically are unremarkable. A more detailed discussion of the diagnosis of mitral valve prolapse may be found in the AHA/ACC guidelines.

Summary

• Mitral valve prolapse is present if there is more than 2 mm displacement of the mitral valve leaflets into the left atrium during systole in a parasternal long-axis or apical three-chamber view on echocardiography.

Treatment

Medical Treatment

Asymptomatic patients require no specific treatment and they should be reassured of their excellent prognosis. Although antibiotic prophylaxis for endocarditis was once advocated for certain patients with MVP, more recent guidelines do not recommend antibiotic prophylaxis in this group of patients.Beta blockers are useful for alleviating symptoms of palpitations, anxiety, and chest pain in certain patients.

Figure

MVP patients without mitral regurgitation should be evaluated every 3 to 5 years. Echocardiography should be performed if the patient has new cardiovascular symptoms or if the physical examination suggests that significant mitral regurgitation has developed. Patients with severe mitral regurgitation or high-risk features should be reviewed with an echocardiogram yearly or more often if their clinical condition warrants it.

Surgery

In MVP patients with severe mitral regurgitation, the indications for mitral valve surgery are similar to those for patients with other causes of severe regurgitation. When surgery is required, mitral valve repair is usually feasible . Repair is characterized by low mortality and long-lasting durability; the 10-year reoperation-free survival rate ranges between 93% and 96%.A more detailed discussion of the management of mitral valve prolapse may be found in the AHA/ACC guidelines.

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