Mitral Regurgitation
The mitral valve is the heart valve between the left atrium and the left ventricle. Mitral regurgitation is where this valve leaks, allowing blood to flow backwards as well as forwards.
What causes mitral regurgitation?
Mitral regurgitation is caused either by a problem with the valve itself (primary or degenerative mitral regurgitation) or by a problem with the heart chamber the valve is anchored to (secondary or functional mitral regurgitation).
Primary mitral regurgitation is most often due to mitral leaflet prolapse — where the leaflets do not properly come together when the valve should be closed. Secondary mitral regurgitation is caused by enlargement of one of the chambers the valve is anchored to. Most commonly this is a dilated left ventricle, often due to a cardiomyopathy or after a previous heart attack.
How is mitral regurgitation assessed?
Patients with mitral regurgitation usually have a murmur on examination. From there, imaging takes over.
- Electrocardiogram (ECG) — looks for atrial fibrillation (common with longstanding mitral disease) and chamber enlargement.
- Transthoracic echocardiogram (TTE) — the principal test. Establishes the cause (primary or secondary), grades the severity (mild, moderate or severe), and assesses heart function.
- Transoesophageal echocardiogram (TOE) — much higher-resolution images of the mitral valve, essential for planning any intervention.
- Cardiac MRI — used in selected patients to quantify the regurgitant volume more precisely and assess left ventricular function, particularly when echo findings are equivocal.
- Cardiac CT — adds anatomical detail and is part of the planning workup when transcatheter intervention is being considered.
- Stress echocardiography — clarifies the haemodynamic significance in patients whose symptoms seem out of proportion to the resting findings.
- Ambulatory ECG monitoring — if atrial fibrillation is suspected but not yet documented.
Patients with significant mitral regurgitation are followed up at regular intervals. When the leak becomes severe and the patient develops symptoms, or when heart function starts to deteriorate, treatment should be considered.
How is mitral regurgitation treated?
Mild and moderate mitral regurgitation is generally managed with medication and observation. Once it becomes severe and the patient develops symptoms, mitral valve repair or replacement should be considered.
For most patients, open-heart surgery remains the preferred treatment — and where possible the surgeon will repair the valve, as this gives the best long-term result. If the valve is not repairable, mitral valve replacement (with either a tissue or mechanical valve) is offered. For patients who are at increased risk for surgery — for example because of age, frailty, or other significant medical problems — and for most patients with secondary mitral regurgitation, a minimally invasive technique called mitral transcatheter edge-to-edge repair (TEER), with the Pascal or MitraClip device, may be recommended.