Mitral Regurgitation: Causes, Diagnosis, and Intervention

Mitral regurgitation (MR), also known as mitral valve insufficiency, is a common valvular heart condition where the mitral valve does not close properly, allowing blood to leak backwards into the left atrium. This backflow increases the workload on the heart and can lead to symptoms such as shortness of breath, fatigue, palpitations, and, in severe cases, heart failure. MR affects millions worldwide and can range from mild and asymptomatic to severe and life-threatening.

Early and accurate diagnosis is critical to preventing progression and preserving heart function. Modern evaluation relies heavily on advanced imaging—such as transthoracic echocardiography, 3D transesophageal echocardiography, cardiac CT, and cardiac MRI—to assess valve anatomy, quantify regurgitation, and guide decision-making.

Once the mechanism and severity of MR are established, treatment planning can begin. Options range from medical management and minimally invasive repair techniques like transcatheter edge-to-edge repair (TEER) to advanced interventions such as transcatheter mitral valve replacement (TMVR)  for patients unsuitable for surgery. By integrating imaging findings with patient-specific factors, clinicians can tailor interventions to achieve the best possible outcomes.

What Causes Mitral Regurgitation?

Mitral regurgitation arises from various underlying mechanisms, commonly classified as:

• Primary (Degenerative) MR: Structural abnormalities of the mitral valve apparatus, including mitral valve prolapse (MVP), myxomatous degeneration, or fibroelastic deficiency, which cause leaflet mal-coaptation.
• Secondary (Functional) MR: The mitral valve leaflets are structurally normal but fail to close effectively due to left ventricular dilation or remodelling, often secondary to ischemic heart disease or cardiomyopathy.
• Other causes include rheumatic heart disease, infective endocarditis, mitral annular calcification, and ischemic damage following myocardial infarction.

Each cause requires specific clinical considerations for diagnosis and management.

Symptoms and Disease Progression

Symptoms of mitral regurgitation can develop gradually and may include:

• Shortness of breath, especially during exertion or when lying flat 
• Fatigue and decreased exercise tolerance 
• Palpitations or irregular heartbeat due to atrial fibrillation 
• Swelling in legs or abdomen (in advanced cases) 

Mild MR can remain asymptomatic for years but may progress to cause volume overload, left atrial enlargement, pulmonary hypertension, and heart failure if untreated. Understanding disease progression through regular follow-up imaging is key to timely intervention.

Diagnostic Coding and Clinical Documentation

Accurate clinical documentation supports appropriate patient care and reimbursement. Common ICD-10 codes related to mitral regurgitation include:

• I34.0 – Nonrheumatic mitral valve insufficiency
• I34.1 – Nonrheumatic mitral valve prolapse 
• I05.1 – Rheumatic mitral insufficiency 
• Z95.2 – Presence of prosthetic heart valve (post mitral valve repair or replacement)

Documentation should reflect MR severity (e.g., “trace,” “mild,” “moderate”) to guide monitoring and treatment planning.
 

Differentiating Mitral Valve Prolapse and Mitral Regurgitation

Mitral valve prolapse (MVP) is a frequent cause of MR but does not always lead to significant regurgitation. MVP is characterized by leaflet displacement into the left atrium during systole and is often benign. However, progression to MR can occur, particularly if chordae tendineae rupture or leaflet thickening develops.

Distinguishing MVP from MR is essential for patient management. Echocardiography remains the diagnostic standard for MVP, with advanced CT imaging valuable in complex anatomy or pre-procedural planning.
 

How Imaging Is Used to Diagnose Mitral Regurgitation

Timely and accurate diagnosis of mitral regurgitation (MR) is essential for determining the best course of treatment and long-term management. Noninvasive imaging tools—particularly echocardiography, transesophageal echo, and 4D flow MRI—form the foundation of evaluation. These tools provide insight into valve anatomy, regurgitant flow, and functional impact on the heart.

Echocardiographic Evaluation

A mitral regurgitation echo is often the first step in diagnosis. This test evaluates regurgitant volume, jet direction, chamber size, and overall cardiac function. Early-stage cases like trace mitral valve regurgitation or mild to moderate mitral valve regurgitation are typically found during routine echocardiography.

For more precise visualization, TEE—especially 3D TEE mitral valve imaging—offers enhanced resolution. This includes the bicommissural view TEE, short axis mitral valve plane, and the ability to assess specific leaflet segments such as A1, A2, A3. These views help differentiate between types of regurgitation and identify causes such as mitral valve prolapse or leaflet restriction.

Other echocardiographic parameters like mitral valve area pressure half-time, DVI mitral valve, and flow reversal are used to quantify severity and guide next steps. These tools are also helpful in identifying conditions like nonrheumatic mitral valve insufficiency and mild mitral valve regurgitation—often asymptomatic but clinically significant over time.

For advanced echo analysis, visit our echocardiography software page.

4D Flow MRI in Functional Assessment

When TTE and TEE findings are inconclusive or complex, 4D flow MRI plays a critical role. This technique captures time-resolved, three-dimensional data that maps the path and volume of blood through the mitral orifice.

It’s particularly useful in cases of:

• Moderate to severe mitral regurgitation
• Concomitant pulmonary hypertension
• Mitral valve regurgitation and mitral valve prolapse overlap
• Situations where mild mitral valve regurgitation and exercise cause symptoms

Our MR 4D Flow solution provides objective flow quantification, assisting in the staging of disease and tracking changes over time.

Learn more on the MR 4D Flow product page.

Supporting Diagnosis with Clinical Criteria

The integration of imaging with clinical findings and guidelines is critical. This includes:

• Recognizing when trace mitral valve regurgitation is normal
• Understanding symptoms of mitral valve prolapse
• Identifying distinguishing features of mitral valve prolapse vs mitral regurgitation
• Adhering to ASE mitral stenosis and ESC diagnostic criteria
• Recognizing common co-pathologies like mild tricuspid valve regurgitation and mitral valve regurgitation

Planning a complex case? Explore 3mensio mitral valve for procedural imaging and planning.

Imaging for Repair Planning

When intervention is considered—whether surgical or transcatheter—imaging becomes even more critical. TEE MV repair guidance is standard for robotic mitral valve repair and intraoperative assessment. Interventional tools like MitraClip echo and MitraClip TEE help optimize device placement and assess for residual jets. Segmental imaging aids in approaches like Alfieri stitch mitral valve or commissuroplasty valve procedures. Imaging also plays a key role in identifying who is a candidate for mitral valve clip based on anatomy and regurgitation severity.

Conclusion

Mitral regurgitation is a complex condition requiring precise diagnosis, tailored intervention, and multidisciplinary expertise to achieve optimal outcomes. Advances in imaging, device technology, and transcatheter techniques such as Transcatheter Mitral Valve repair and Transcatheter Mitral Valve Replacement have expanded treatment options for patients previously deemed inoperable.