12.8 Treatment strategies in mitral regurgitation
Echocardiography is not only the primary modality to diagnose mitral regurgitation but also to determine the best treatment strategy. Basically one needs to make the following decisions:
- Whether regurgitation is relevant
- If and when surgery is required.
- Which surgical approach one should attempt (repair vs. replacement).
- Whether surgery cannot be performed and a conservative approach (or transplantation) must be adopted.
- Whether mitral valve repair should be performed when bypass surgery is indicated.
- When an interventional approach (Mitraclip) is feasible.
Progression of the disease is usually based on sequential echo investigations. Transesophageal echo may also be useful when transthoracic echo fails to determine the exact severity, mechanism, or morphology of the valve.

Finally, exercise echocardiography may be used to obtain information about the functional reserve of the ventricle. It may unmask "dynamic" forms of mitral regurgitation, in which mitral regurgitation increases during exercise.
12.8.1 Structural mitral regurgitation
Patients with acute severe mitral regurgitation should be operated on as early as possible. In the presence of severe chronic mitral regurgitation all symptomatic patients (as long as their ejection fraction is still above 30% and the end-systolic diameter is > 55 mm) are candidates for surgery.
Surgery is also indicated when the ejection fraction is below 60% and LV diameter > 45 mm.
| Indication |
|---|
| LVEF < 60 % |
| ESD > 45 mm |
| New afib |
| sPAP >50 mmHg |
| or when the patient is symptomatic |
| LVF < 30%: No surgery (conservative, HTX) |
The best treatment strategy for asymptomatic patients with severe mitral regurgitation and preserved left ventricular function is less clear. This is also reflected in the guidelines of international societies, which state that one may select the strategy of watchful waiting or surgery. Important variables that must be considered here are the risk of surgery, the likelihood of repair, the presence of arrhythmia, and the magnitude of pulmonary artery pressure (> 50 mmHg).
When left ventricular function drops below 30% and end-systolic diameter is above 55 mm, it might be too late for surgery because left ventricular function will deteriorate further after surgery (see hemodynamics of mitral regurgitation). A conservative approach or heart transplantation are possible options.

| Echocardiographic approach in asymptomatic patients |
|---|
| Monitor LVF and size |
| Check for pulmonary hypertension |
| Atrial size/Risk for Afib |
| Other tests! |
| Earlier surgery if repair is likely! |
| Other factors to consider |
|---|
| Type of valve |
| Contraindication to warfarin |
| Additional Indication for heart surgery (CABG, other valve, aneurysm) |
| Patient's age |
| Comorbidities |
| Alternative new approaches (e.g. MitralClip) |
12.8.2 Functional Mitral Regurgitation
The outcome of the treatment of functional mitral valve regurgitation is poor, especially when left ventricular function is severely reduced. Mitral valve repair (annuloplasty) should be considered when cardiac surgery is indicated for other reasons and regurgitation is at least moderate. Whether or not one should perform isolated mitral valve surgery is a more difficult decision. Other tests such as exercise/stress echocardiography may be required to determine the functional reserve of the ventricle.
12.8.3 Repair versus replacement
Mitral valve repair is better than valve replacement. It should be attempted whenever possible because patients with artificial valves are subject to a high risk of complications in prosthetic valves. In addition, repair preserves left ventricular function to a greater extent. However, not all valves can be repaired. Although it is ultimately the surgeon's decision, echocardiography may provide valuable information as to whether repair is feasible. Factors that do not favor repair are the following:

- Severely calcified valves and annulus
- Post-rheumatic mitral valves
- Extensive valve involvement (e.g. mitral valve prolapse)
- Involvement of the anterior vs. posterior leaflet
- Commissural defects
12.8.4 Recent developments
Several interventional valve procedures are being developed at the present time. These provide a therapeutic option for patients who are no candidates for mitral valve surgery. This less invasive approach may be used as an alternative for patients who have severely reduced left ventricular function or those who rank as high-risk patients for surgery (logistic Euroscore around 20%). The most promising technique (and the only one which is currently approved) is the MitraClip procedure. Using a transfemoral venous access, a clip is placed between the anterior and posterior leaflet to increase coaptation. Placement of this clip leads to a double orifice valve, similar to the Alfieri technique. It is a surgical "bail out" method to "repair" the mitral valve. This procedure has been shown to reduce the degree of mitral regurgitation in patients with organic (structural) or functional mitral regurgitation. Echocardiography plays an important role in selecting candidates for the MitraClip procedure. Criteria taken into account here are the presence of a central origin of the jet, a coaptation depth >11 mm, and length less than 2 mm. Thus, detailed assessment of the mitral valve with transthoracic and transesophageal echocardiography must be performed prior to the intervention. Three-dimensional echocardiography can provide additional information, especially the view in which the mitral valve is displayed en face.

Transesophageal echocardiography should also be used to monitor the various steps of procedures such as transeptal puncture, navigation of the delivery system, positioning of the clip arms, deployment of the clip, and assessment of mitral regurgitation after the procedure
12.9 General remarks
Assessment of the mitral valve requires a thorough understanding of mitral valve anatomy, function, and pathologies. You will need good imaging skills and expertise to mentally reconstruct the various cut planes in order to obtain a true "3D appreciation" of the pathology of jets. Mitral regurgitation affects the heart and other pathologies in many ways. To understand these effects you must also be able to correctly interpret the hemodynamic consequences of regurgitation. You will be confronted with questions like: Is mitral regurgitation really significant? Can it explain symptoms? Is the ventricle still able to cope with volume overload? Many decisions will be based on the answers you obtain to these questions.
Therefore, it is important to talk to clinicians and surgeons, follow patients closely, and perform additional tests whenever necessary.