Mitral Regurgitation

Key points

• Incomplete systolic closure of the mitral orifice resulting in backflow of blood from the left ventricle to the left atrium
• The characteristic finding is an apical holosystolic murmur; radiation to the axilla is common
• Most patients have mild regurgitation, are asymptomatic, and never need valve surgery
• Moderate-to-severe regurgitation can cause gradual compensatory changes to the heart over a period of many years, possibly in the absence of symptoms. Physicians must be alert to the onset of these changes to prevent irreversible damage to the left ventricle or left atrium
• Echocardiography is used to confirm the diagnosis, determine the severity and cause of regurgitation, and assess the need for surgery
• Treatment consists of valve surgery. Valve repair is preferable to valve replacement, and the likelihood of obtaining a repair should be considered when a patient is being evaluated for surgery
• For those who are not surgical candidates, a percutaneous mitral valve clip can be an option to reduce the degree of mitral regurgitation
• For most patients, medical treatment is limited to prophylaxis for endocarditis. Young patients with rheumatic mitral regurgitation require rheumatic fever prophylaxis
• Acute mitral regurgitation may manifest with fulminant pulmonary edema or cardiogenic shock; the murmur in this setting is usually only in early- and mid-systole

Background

Description

• Incomplete systolic closure of the mitral orifice resulting in backflow of blood from the left ventricle to the left atrium
• Caused by an abnormality of the mitral apparatus, which includes the valve leaflets, annulus, chordae tendineae, papillary muscles, and wall of the left ventricle
• Echocardiography reveals a small amount of mitral regurgitation in most healthy adults
• Of note, with significant mitral regurgitation, when caught early, 'normal' left ventricle ejection fraction (LVEF) is usually higher than typical norms (ie, >70%), as there is little keeping blood in the left ventricle during systole due to significant backward (or regurgitant flow) as well as normal cardiac output. It is often concerning to see LVEF drop to below 60% in the setting of severe mitral regurgitation. This is also why LVEF usually needs to be greater than 30% for consideration of surgery, as repair of the regurgitant lesion usually results in a transient, acute, drop in LVEF

Epidemiology

• About 18,000 patients undergo mitral valve surgery each year in the U.S.
• Prevalence increases greatly with age. Fewer than 3% of children have valvular regurgitation of any type. In contrast, studies have shown mild mitral regurgitation in 19% of adults by a mean age of 54 years and in more than 80% of people aged 80 years or more
• Mitral valve prolapse and pneumatic mitral regurgitation are more prevalent in female patients; however, mitral regurgitation is highly prevalent in both men and women who are middle-aged or older. More men than women undergo mitral valve surgery
• May be associated with congenital abnormalities of the heart in Ehlers-Danlos syndrome, Marfan syndrome, and Down syndrome
• Mitral valve prolapse may have a genetic component
• Rheumatic fever is the most common cause of mitral regurgitation outside of industrialized nations. It was rare in the U.S. during the 1970s, but outbreaks occurred in the 1980s
• Rheumatic mitral valve disease is more common in crowded living conditions where streptococcal pharyngitis is readily transmitted

Causes and risk factors

Causes: 

• Mitral valve prolapse (myxomatous degeneration of the mitral valve, sometimes referred to Barlow disease)
• Papillary muscle ischemia or infarction, with possible rupture, secondary to coronary artery disease
• Infective endocarditis
• Myxomatous transformation of the leaflets
• Dilated cardiomyopathy
• Annular calcification, associated with aging
• Rheumatic heart disease should particularly be considered in patients with mitral regurgitation aged younger than 40 years
• Ruptured chordae tendinae
• Ventricular dilation from either ischemic or nonischemic cardiomyopathy
• Mitral annular dilation
• Hypertrophic cardiomyopathy
• Congenital or genetic disorders: Ehlers-Danlos syndrome, Marfan syndrome, and Down syndrome
• Osteogenesis imperfecta
• Systemic lupus erythematosus
• Trauma
• Anorectic drugs: fenfluramine and dexfenfluramine
• Anthracycline chemotherapy
• Radiation injury
• Carcinoid heart disease
• Congenital parachute valve
• 'Senile' or calcific degeneration

Contributory or predisposing factors:

• Aging
• Myocardial infarction or coronary artery disease
• Systemic hypertension
• Hemodynamic stress: pregnancy, anemia, or infection

Associated disorders

Mitral stenosis.

Screening

• There are no public health recommendations for screening. The best way to discover significant mitral regurgitation is through a thorough history and physical
• If there is a murmur or concern for valvular disease, an echocardiogram should be the first test to evaluate for mitral regurgitation

Primary prevention

Summary approach

Prompt treatment of rheumatic fever and potential endocarditis with antibiotics as well as good blood pressure control may help to reduce the development of significant mitral regurgitation.

Population at risk

Illicit drug abusers are at risk for repeated episodes of endocarditis with damage to the mitral valve.

Preventive measures

• Avoid risk factors for endocarditis, including intravenous drug use
• Prompt diagnosis and treatment of rheumatic fever
• Manage hypertension