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: ↑ left atrial volume with normal left atrial compliance and ↑ LV end-diastolic volume → rapid ↑ in LA and pulmonary pressures → 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
- Holosystolic murmur (high-pitched, blowing)
- See also auscultation in valvular defects
American Heart Association (AHA) staging for MR 
- Used to monitor intervals and determine the need for interventions
- Based on echocardiographic criteria of valve anatomy, hemodynamics, and associated cardiac findings (e.g., LV dilation)
- Criteria vary between primary and secondary 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
- Rule out myocardial infarction and consider other .
- Perform transthoracic echocardiography (TTE).
- For suspected acute MR, obtain emergency preoperative diagnostics.
- Consider additional diagnostics (e.g. coronary angiography) based on the suspected etiology.
Acute MR is a medical and surgical emergency, as patients can decompensate rapidly. 
- Indications: to assess the valve apparatus, size and function of left ventricle and atrium, and grade the severity of MR 
|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: 
- 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.
- Chronic MR: ECG changes usually reflect cardiac remodeling.
- Indications: assess for pulmonary edema, rule out other causes of acute dyspnea
- 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.
- Arrange early interfacility transfer if cardiothoracic surgery is not available locally.
- 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) 
- rhythm control to improve hemodynamics.  : Consider
- 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. 
Surgical management 
All patients with acute primary MR should undergo urgent surgical repair or valve replacement.
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). 
- Cardiology consult for further treatment options
Surgical management and transcatheter mitral repair
Chronic primary MR 
- Indications: severe primary MR with any of the following
Chronic secondary MR 
- Indications: Consider for patients with severe MR (stage D) and persistent symptomatic heart failure (NYHA classes III–IV) despite optimal medical management. 
- Heart failure, pulmonary edema
- Cardiogenic shock
- Atrial fibrillation
- Pulmonary artery hypertension
We list the most important complications. The selection is not exhaustive.
- Perform ABCDE assessment.
- Initiate cardiac monitoring and pulse oximetry.
- Rule out myocardial infarction.
- Treat complications of MR.
- Obtain .
- Obtain TTE to confirm the diagnosis.
- Consult cardiology and cardiothoracic surgery.
- Consider early interfacility transfer if required.
- Pursue definitive management, e.g., surgical valve repair or replacement, PCI, or operative revascularization for MI.
- Initiate .
- Transfer to operating room or ICU.