MITRAL REGURGITATION

Written by Dimitrios Vrachatis, Specialist Cardiologist, PhD, National and Kapodistrian University of Athens.

What is mitral regurgitation?

Mitral regurgitation is abnormal backward flow of blood from the left ventricle into the left atrium through the mitral valve.

What is the mitral valve?

The mitral valve connects the left atrium and left ventricle. Its complex structure, known as the mitral apparatus, includes two leaflets, papillary muscles and chordae tendineae.

Normally, after blood passes from the atrium into the ventricle during relaxation, the valve closes tightly to prevent backward flow.

How is mitral regurgitation diagnosed?

Diagnosis uses an echocardiogram. An electrocardiogram or prolonged Holter monitoring may also be performed if arrhythmias are suspected.

Advanced cases may require transoesophageal echocardiography or cardiac MRI to establish severity and mechanism accurately.

What are the symptoms?

Mitral regurgitation can be misleading: it may remain asymptomatic for a long time and only be diagnosed after heart failure develops.

Acute, sudden regurgitation is very different from chronic regurgitation, which develops gradually.

Chronic Mitral Regurgitation

When regurgitation develops gradually, the heart has time to adapt. The left atrium enlarges and the left ventricle develops eccentric hypertrophy.

This maintains adequate function for a time, until compensation eventually fails. Symptoms develop gradually and may include:

Palpitations due to extra beats or atrial fibrillation
Fatigue or breathlessness
Chest pain
Dizziness or feeling faint
Swollen legs
Needing more than one pillow to sleep

Acute Mitral Regurgitation

When regurgitation develops suddenly, the left atrium cannot accommodate the increased blood volume. Pressure rises and is transmitted to the lungs, causing acute pulmonary oedema, or acute heart failure. Emergency surgery is therefore required.

Classification

By cause, regurgitation is:

Primary: damage to a component of the valve apparatus
Secondary: caused by left ventricular dysfunction

By severity, it is classified as:

Mild
Moderate
Severe

Causes

This valve disease has several possible causes:

Congenital valve abnormalities
Mitral valve prolapse
A myocardial infarction involving the papillary muscles
Rupture of the chordae tendineae
Rheumatic fever
Infective endocarditis
Cardiomyopathies, among others

Follow-up

Once moderate mitral regurgitation is diagnosed, regular follow-up is needed to identify deterioration and any need for intervention promptly.

What treatment is available?

Treatment is complex. Intervention, such as valve repair or replacement, depends on the cause and the stage of cardiac enlargement and functional impairment. It concerns severe regurgitation only. Medication is not specific to regurgitation itself: it may treat the underlying cause or associated heart failure.

Surgical Repair or Replacement?

Repair is preferred over prosthetic replacement when technically feasible.

Choosing the right time is critical: intervention should take place as soon as symptoms or signs of functional or structural deterioration appear.

This applies to chronic regurgitation. Acute regurgitation requires immediate cardiac surgery.

Mechanical or Biological Prosthetic Valve?

The choice depends on age and individual characteristics. Mechanical valves last longer, reducing the likelihood of another operation, but require lifelong anticoagulation with acenocoumarol or warfarin. Biological valves do not require anticoagulation for the valve itself but have a shorter lifespan.

Are minimally invasive options available?

For some patients with symptomatic severe regurgitation who are at high surgical risk, catheter-based techniques such as edge-to-edge repair using devices like MitraClip may be possible.