What Is Mitral Regurgitation?

Mitral regurgitation (MR) is a condition in which the mitral valve—located on the left side of the heart—does not close completely. When this happens, some blood leaks backward instead of moving forward through the heart as it should.

The mitral valve sits between the left atrium (upper chamber) and left ventricle (lower chamber). With each heartbeat, it opens to allow blood to flow downward and then closes tightly to keep blood from leaking back up. In mitral regurgitation, that seal is incomplete, allowing blood to move in the wrong direction.

Small leaks may cause little to no symptoms. Larger leaks, however, force the heart to work harder and can eventually lead to heart enlargement, heart failure, and rhythm disturbances.

Why Mitral Regurgitation Matters

When blood leaks backward through the mitral valve:

• Less blood is pumped forward to the body

• Pressure builds up in the lungs

• The heart compensates by enlarging and working harder

Over time, these changes can reduce heart efficiency and lead to worsening symptoms and complications—especially if MR goes undetected.

Mitral regurgitation is the most common valve disorder in the United States, particularly in adults over age 65.

Types of Mitral Regurgitation

There are two main categories:

Primary (Degenerative) Mitral Regurgitation

The problem lies in the valve itself. Structural damage prevents the leaflets from closing properly.
Common causes include:

• Mitral valve prolapse

• Connective tissue disorders

• Prior infections (endocarditis, rheumatic disease)

• Congenital valve abnormalities

Secondary (Functional) Mitral Regurgitation

The valve is structurally normal, but the heart chambers supporting it are enlarged or weakened.
Common causes include:

• Cardiomyopathy

• Prior heart attack

• Long-standing atrial fibrillation

MR can also be described as:

• Chronic (developing gradually)

• Acute (sudden and severe)

Symptoms of Mitral Regurgitation

Mild MR may cause no symptoms. As regurgitation worsens, symptoms may include:

• Shortness of breath (especially with activity or lying flat)

• Fatigue or reduced exercise tolerance

• Heart palpitations

• Swelling in the legs or feet

• Cough or chest discomfort

• Lightheadedness or near-fainting

Sudden onset of severe shortness of breath, chest tightness, or rapid breathing is a medical emergency and requires immediate care.

How Echocardiography Diagnoses Mitral Regurgitation

Echocardiography is the primary tool used to diagnose and monitor mitral regurgitation.

An echocardiogram allows providers to:

• Visualize valve structure and leaflet motion

• Detect backward blood flow using color Doppler

• Measure severity of regurgitation

• Assess heart size and pumping function

• Evaluate pressure changes in the lungs

Most patients start with a transthoracic echocardiogram (TTE). If more detail is needed—especially for surgical planning—a transesophageal echocardiogram (TEE) may be performed.

Echocardiography also plays a crucial role in timing intervention, often identifying changes before symptoms become severe.

How Mitral Regurgitation Is Managed

Treatment depends on:

• Severity of regurgitation

• Presence of symptoms

• Heart size and function

• Whether MR is primary or secondary

Management options may include:

• Monitoring with routine echocardiograms for mild cases

• Medications to manage symptoms or associated heart failure

• Valve repair (surgical or transcatheter)

• Valve replacement when repair is not possible

Unlike medications, repairing or replacing the valve addresses the underlying problem, not just symptoms.

Why Early Detection Is So Important

Mitral regurgitation often progresses silently. By the time symptoms appear, heart damage may already be underway.

Regular echocardiographic monitoring helps:

• Detect worsening MR early

• Prevent irreversible heart enlargement

• Optimize timing of intervention

• Improve long-term outcomes

The Bottom Line

Mitral regurgitation is a common valve condition that ranges from mild and manageable to severe and life-threatening. Because symptoms may be subtle or delayed, echocardiography is essential for diagnosis, severity assessment, and long-term management.

If you’ve been told you have a heart murmur, experience unexplained shortness of breath, or have known heart disease, an echocardiogram is often the most important next step.