- Clinical science
Mitral regurgitation (MR) is the leakage of blood from the left ventricle into the left atrium due to incomplete closure of the mitral valve during systole. It is a common form of valvular disease and categorized according to onset (into acute and chronic forms) and etiology. Primary MR involves the structure of the mitral valve whereas secondary MR is a result of different pathologies that lead to valvular incompetence (e.g., cardiomyopathy). Ischemic MR can be acute (e.g., papillary muscle rupture in myocardial infarction) or chronic (in coronary artery disease). Symptoms vary from cardiogenic shock and flash pulmonary edema in acute manifestations to mild symptoms such as cough and dyspnea in chronic cases. Echocardiography is the diagnostic modality of choice; further imaging and treatment options are determined by the etiology. The definitive treatment in primary MR is surgical repair or valve replacement, while therapy of an underlying condition, e.g., percutaneous coronary intervention (PCI) in coronary artery disease, is the mainstay of therapy in secondary MR. Pharmacological treatment aims to reduce the degree of heart failure.
- Primary MR (organic): mitral regurgitation caused by direct involvement of the valve leaflets or chordae tendinae 
- Secondary MR (functional): caused by changes of the left ventricle that lead to valvular incompetence
- Acute MR: Acute dysfunction of the mitral valve leads to volume overload and symptoms of acute heart failure. 
- Chronic MR
- Acute MR: → ↑ LV end-diastolic volume → rapid ↑ LA and pulmonary pressure → pulmonary venous congestion → pulmonary edema
- Chronic (compensated) MR: : progressive dilation of the LV (via eccentric hypertrophy) → ↑ volume capacity of the LV (preload and afterload return to normal values) → ↑ end-diastolic volume → maintains ↑ stroke volume (normal EF)
- Chronic (decompensated) MR: progressive LV enlargement and myocardial dysfunction → ↓ stroke volume → ↑ end-systolic and end-diastolic volume → ↑ LV and LA pressure → pulmonary congestion, possible acute pulmonary edema, pulmonary hypertension, and right heart strain
Acute mitral regurgitation 
- Signs and symptoms
- Auscultation 
Chronic mitral regurgitation
- Signs and symptoms
- Lateral displacement of the apical impulse
- Quiet S1 heart sound
- S3 heart sound in advanced stages of disease
- S4 heart sound may be heard in functional MR.
- Holosystolic murmur (high-pitched, blowing)
- See also auscultation in valvular defects
Transthoracic echocardiography (TTE) is used to confirm the diagnosis and classify severity in patients with suspected MR. Check ECG and troponin in acute MR to rule out myocardial infarct. Consider additional diagnostics (e.g., coronary angiography, blood cultures) depending on patient stability and the suspected underlying condition.
- American Heart Association (AHA) staging for MR 
|AHA staging for mitral valve regurgitation |
|Stage||Extent of mitral regurgitation|
- Uses echocardiography findings to classify leaflet motion (Carpentier types I–III). 
- Used in the planning of surgical repair
- Troponin: Elevation may indicate myocardial ischemia.
- Acute MR: typically normal because of the acute onset of symptoms 
- Chronic MR: normal or elevated as regurgitation severity increases and the left ventricle is remodeled 
- Blood cultures: in suspected infective endocarditis (at least three sets) 
Myocardial infarction must be ruled out in patients presenting with acute mitral regurgitation!
- Acute MR: findings are often nonspecific and include:
- Chronic MR: ECG changes usually reflect cardiac remodeling.
- Used to 
- TTE: modality of choice for the initial assessment of all patients with suspected valvular abnormality 
- Transesophageal echocardiography (TEE): indicated prior to surgery and during the diagnostic workup of MR if TTE is inadequate 
Findings in primary mitral regurgitation 
|Echocardiographic characteristics of primary mitral regurgitation|
|Parameter||Acute MR||Chronic MR|
|Valve movement or function|| || |
|Aortic valve opening || || |
|Pulmonary vein flow || || |
|Left atrium|| || |
|Left ventricle size|| || |
|LVEF|| || |
|Pulmonary artery pressure || || |
|Right ventricle ejection fraction|| || |
Findings in secondary mitral regurgitation 
- May include
- Normal valve anatomy but abnormal function
- Signs of an underlying condition may be present (e.g., apical left ventricular ballooning in takotsubo cardiomyopathy)
- Decompensated MR and acute MR: signs of pulmonary congestion (see ) 
- Acute MR: normal-sized cardiac silhouette 
- Chronic MR: Changes related to cardiac remodeling and associated heart failure may be visible.
- LV enlargement: laterally displaced left cardiac border
- LA enlargement: straightening of the left cardiac border and double density sign 
- Annular calcification may be visible as a C-shaped density. 
In primary MR, additional diagnostics should be considered if echocardiography does not allow for the adequate assessment of mitral valve function. In secondary MR, consider advanced diagnostics to determine the underlying condition (e.g., coronary artery disease).
- Cardiac MRI (CMR): if both TTE and TEE findings are inconclusive, and for suspected cardiomyopathy or ischemic MR 
- Stress echo: in ischemic MR and to help assess the need for surgery 
- CT angiography: in suspected ischemic cardiomyopathy
- Coronary angiography: in suspected ischemic MR, prior to surgical intervention
Acute mitral regurgitation
- Management of acute MR is complex and cardiology and cardiothoracic surgery should be consulted as early as possible.
- All patients with acute primary MR should undergo urgent surgical repair or valve replacement.
- While awaiting surgery, any symptoms of heart failure should be managed with medical therapy (e.g., diuretics, nitrates, antihypertensive drugs).
- If secondary MR is suspected, identify and treat the underlying cause (e.g., revascularization therapy for ischemic MR) 
Surgical therapy 
All patients with acute primary MR should undergo urgent surgical repair or valve replacement.
- Heart failure management: See “Treatment” in heart failure.
- Hypotension: inotropes (e.g., dobutamine ) 
- Atrial fibrillation: consider cardiac resynchronization therapy to improve hemodynamics. 
Heart failure treatment may worsen hypotension; use caution in hemodynamically unstable patients.
- Patients whose symptoms continue to deteriorate despite medical therapy 
- Unstable patients prior to surgery
- Intra-aortic balloon pump (IABP) 
- Consider left ventricular assist device (LVAD) or ECMO in patients who are deteriorating despite pharmacological therapy and IABP. 
Chronic mitral regurgitation
Management of chronic MR is guided by the symptoms and extent of heart failure and the cause of MR. Medical therapy should be initiated in all patients to optimize cardiac function but surgery is the definitive treatment option.
- Identify and treat any underlying cause (particularly in secondary MR). 
- Heart failure management: see “Treatment” in heart failure 
- Cardiology consult for further treatment options
Surgical management and transcatheter mitral repair
Chronic primary MR
- Indications 
- Contraindications: Once LVEF is < 30%, surgery is generally not recommended because of the high mortality rate and low likelihood of symptom improvement. 
Chronic secondary MR  
- Indications: consider for patients with severe MR and persistent symptomatic heart failure (NYHA classes III–IV) despite optimal medical management 
- ABCDE assessment
- Initiate inotropic support (e.g., dobutamine) for hypotension
- Cardiology and cardiac surgery consult
- TTE to confirm the diagnosis
- Consider TEE:
- If TTE is inconclusive
- For preoperative planning (can also be done in the OR)
- Start medical therapy for heart failure (e.g., nitroprusside, diuretics)
- Consider definitive management options based on the underlying cause.
- Primary MR : immediate surgical repair/valve replacement
- Secondary MR: identify and treat the underlying cause
- Continuous cardiac monitoring
- Continuous pulse oximetry
- Place a urinary catheter.
- Transfer to OR or ICU.