Cardiology > Mitral Regurgitation

1. Background
2. I) Definition
   Mitral regurgitation (MR) is the retrograde flow of blood from the left ventricle into the left atrium during systole due to incompetent closure of the mitral valve. This volume overload increases left atrial and pulmonary pressures, eventually leading to left ventricular dilation, atrial fibrillation, pulmonary hypertension, and heart failure if untreated.
3. II) Classification/Types

By Etiology: 

• Primary (Degenerative) MR: Intrinsic valve disease (e.g., myxomatous degeneration, mitral valve prolapse, rheumatic disease, endocarditis). 

• Secondary (Functional) MR: Result of left ventricular dilation or papillary muscle dysfunction, seen in ischemic or dilated cardiomyopathy. 

By Onset: 

• Acute MR: Sudden onset, often due to papillary muscle rupture (MI), endocarditis, or trauma. 

• Chronic MR: Progressive valve degeneration or functional remodeling over time. 

By Severity (based on echocardiographic criteria): 

• Mild 

• Moderate 

• Severe (quantified using regurgitant volume, effective regurgitant orifice area, and vena contracta width) 

III) Pathophysiology 

1. IV) Epidemiology

• Sex: Myxomatous degeneration more common in women; ischemic MR more common in men. 

• Age: Prevalence increases with age due to degenerative changes. 

• Geography: Degenerative MR more common in high-income countries; rheumatic MR in low- and middle-income countries. 

• Comorbidities: Often associated with hypertension, coronary artery disease, or heart failure. 

2. Etiology
3. I) Causes 

• Myxomatous valve degeneration (e.g., mitral valve prolapse) 

• Rheumatic heart disease 

• Infective endocarditis 

• Ischemic heart disease (papillary muscle rupture/dysfunction) 

• Cardiomyopathy (dilated or hypertrophic) 

• Congenital anomalies (e.g., cleft mitral valve) 

• Mitral annular calcification 

• Chest trauma or radiation 

1. II) Risk Factors

• Age >60 years 

• Coronary artery disease or prior MI 

• Rheumatic fever history 

• Connective tissue disorders (e.g., Marfan, Ehlers-Danlos) 

• Atrial fibrillation 

• Endocarditis 

3. Clinical Presentation
4. I) History (Symptoms)

• Fatigue and reduced exercise tolerance 

• Dyspnea on exertion, orthopnea, PND 

• Palpitations (especially with atrial fibrillation) 

• Signs of heart failure (in advanced disease) 

• Acute MR: Sudden onset dyspnea, pulmonary edema, hypotension 

• II) Physical Exam (Signs)
  Vital Signs:

• Tachycardia 

• Hypotension (in acute MR) 

• Cardiac Exam: 

• Holosystolic murmur best heard at the apex, radiating to the axilla 

• S3 gallop (suggests volume overload) 

• Displaced hyperdynamic apical impulse (in chronic severe MR) 

• Pulmonary: 

• Rales or crackles in pulmonary edema 

• Possible signs of pulmonary hypertension in chronic MR 

• Peripheral: 

• Peripheral edema (in right-sided heart failure) 

• Elevated JVP (advanced disease) 

4. Differential Diagnosis (DDx)

• Mitral stenosis 

• Aortic regurgitation 

• Tricuspid regurgitation 

• Heart failure with preserved/reduced EF 

• Cardiomyopathy (dilated, hypertrophic) 

• Atrial septal defect 

• Constrictive pericarditis 

5. Diagnostic Tests

Initial Tests: 

• Transthoracic Echocardiogram (TTE): 

• Confirms MR severity 

• Assesses valve morphology, regurgitant volume, and LV function 

• Measures left atrial and ventricular size 

• Transesophageal Echo (TEE): 

• Superior for valve visualization, especially in endocarditis or surgical planning 

• Electrocardiogram (ECG): 

• Atrial fibrillation 

• Left atrial enlargement or LV hypertrophy 

• Chest X-ray: 

• Left atrial and ventricular enlargement 

• Pulmonary vascular congestion 

• BNP/NT-proBNP: 

• Elevated in decompensated MR with heart failure 

• Cardiac MRI: 

• Precise quantification of regurgitant volume and chamber size 

• Cardiac Catheterization: 

• Coronary anatomy before surgery 

• Assess hemodynamics in unclear cases 

• 6. Treatment 

• I) Medical Management: 

• Heart Failure Management: 

• Diuretics for volume overload 

• Afterload reducers (ACE inhibitors, ARBs) in functional MR 

• Beta-blockers in chronic MR with LV dysfunction 

• Rate Control and Anticoagulation: 

• Beta-blockers, calcium channel blockers, or digoxin for atrial fibrillation 

• Anticoagulation (warfarin) in atrial fibrillation, prior embolism, or left atrial thrombus 

• Endocarditis Prophylaxis: 

• Not routine unless prior endocarditis or prosthetic valve 

• II) Interventional/Surgical: 

• Surgical Mitral Valve Repair or Replacement: 

• Indicated for severe symptomatic MR 

• Also for asymptomatic severe MR with LV EF ≤60% or LV end-systolic dimension >40 mm 

• Valve repair preferred over replacement when feasible 

• Transcatheter Mitral Valve Repair (e.g., MitraClip): 

• For select high-risk surgical patients with severe symptomatic MR 

• More commonly used in functional MR 

• 7. Patient Education, Screening, Vaccines 

• Importance of adherence to medications and follow-up 

• Monitor for symptoms of worsening heart failure (e.g., dyspnea, edema) 

• Weight tracking to detect fluid retention 

• Limit sodium intake if volume overload present 

• Avoid excessive physical exertion in symptomatic patients 

• Vaccinations: 

• Influenza annually 

• Pneumococcal vaccine 

• COVID-19 vaccination 

• 8. Consults 

• Cardiology: All moderate to severe MR or symptomatic patients 

• Cardiothoracic Surgery: Evaluation for mitral valve surgery 

• Interventional Cardiology: For transcatheter interventions 

• Electrophysiology: If recurrent or symptomatic atrial fibrillation 

• Infectious Disease: If endocarditis suspected 

• Primary Care/Internal Medicine: For chronic disease optimization 

• 9. Follow-Up 

• Regular TTE: 

• Annually for asymptomatic severe MR 

• Every 6–12 months if LV size/function changes 

• Monitor for development of atrial fibrillation 

• Assess progression of symptoms and candidacy for intervention 

• Optimize management of comorbid conditions (e.g., hypertension, CAD) 

• Reinforce education on warning signs and when to seek care