What is the treatment for a patient with severe mitral regurgitation?

Treatment of Severe Mitral Regurgitation

Surgical mitral valve repair is the definitive treatment for severe mitral regurgitation, reducing mortality by approximately 70% compared to medical management, and should be performed in all symptomatic patients regardless of left ventricular function, as well as in asymptomatic patients with LVEF ≤60% or LVESD ≥40 mm. 1

Critical First Step: Distinguish Primary from Secondary MR

The treatment algorithm diverges completely based on MR etiology, making this distinction essential:

• Primary (degenerative) MR involves structural valve abnormalities including prolapse, flail leaflet, or chordal rupture 1
• Secondary (functional) MR results from left ventricular dysfunction with structurally normal leaflets 1
• Transthoracic echocardiography is the fundamental diagnostic tool to make this distinction 1

Treatment Algorithm for Primary (Degenerative) MR

Symptomatic Patients

Surgery is indicated for ALL symptomatic patients with severe primary MR, regardless of left ventricular function (Class I recommendation). 2, 1

• Mitral valve repair is strongly preferred over replacement when anatomically feasible, reducing mortality by approximately 70% 1, 3
• Surgery should be performed within 2 months once indications are met, as even mild symptoms at time of surgery are associated with worse cardiac function post-operatively 2

Asymptomatic Patients

Surgery is indicated when ANY of the following are present:

Class I indications:

• LVEF ≤60% 2, 1
• LVESD ≥40 mm (or ≥22 mm/m² BSA in patients of small stature) 2, 1

Class IIa indications:

• New-onset atrial fibrillation 2, 1
• Pulmonary artery systolic pressure >50 mmHg at rest 2, 1
• Flail leaflet with LVESD ≥40 mm 2

Class IIb indications (when high likelihood of durable repair exists and surgical risk is low):

• Left atrial volume index ≥60 mL/m² BSA with sinus rhythm 2, 1
• Pulmonary hypertension on exercise (systolic PAP ≥60 mmHg) 2, 1

Surgical Technique Considerations

• Valve repair is preferable to replacement in all cases where anatomically feasible 2, 1
• Best outcomes occur in centers with operative mortality <1% and repair rates ≥80-90% 3
• When repair is not feasible, valve replacement should be performed with chordal-sparing techniques to preserve ventricular function 4

Treatment Algorithm for Secondary (Functional/Ischemic) MR

Mandatory First-Line Therapy: Optimize Medical Management

Guideline-directed medical therapy (GDMT) is mandatory as the first step before considering any intervention for secondary MR. 1

GDMT includes:

• ACE inhibitors/ARBs or sacubitril/valsartan 1
• Beta-blockers 1
• Mineralocorticoid receptor antagonists 1
• SGLT2 inhibitors 1
• Diuretics and nitrates as needed 1

Cardiac Resynchronization Therapy

• CRT should be implemented in patients meeting guideline criteria, as it may reduce MR severity through improved papillary muscle synchronization 1

Surgical Indications for Secondary MR

Surgery is indicated when:

Class I indication:

• Patient is undergoing CABG AND has severe ischemic MR AND LVEF >30% 1, 4
• For severe ischemic MR with LVEF >30%, mitral valve surgery should be performed concomitantly with CABG 4

Class IIb indications:

• Patient remains symptomatic despite optimal GDMT and has low surgical risk 1
• Severe ischemic MR with LVEF ≤30% undergoing CABG (surgery may be considered) 4
• Moderate ischemic MR with viable posteroinferior wall undergoing CABG (CABG alone without mitral surgery may be considered) 4

Surgical Technique for Secondary MR

• Mitral valve repair with small undersized rigid annuloplasty ring is the preferred method (Class IIa, Level B) 4
• Mitral valve replacement should be considered in patients with unfavorable morphological characteristics or high risk of MR recurrence 4
• Chordal-sparing techniques must be used during replacement to preserve ventricular function 4

Medical Therapy Limitations

There is no evidence to support the use of vasodilators, including ACE inhibitors, in chronic primary MR. 2

• Beta-blockers and RAAS inhibitors have the strongest evidence for beneficial effects in primary MR, potentially lessening MR severity and preventing LV dysfunction deterioration 5
• However, in hypertrophic cardiomyopathy or mitral valve prolapse, vasodilators can paradoxically increase MR severity 5
• Medical therapy alone is not a substitute for surgery when surgical indications are met 2, 6

Acute Mitral Regurgitation Management

For acute severe MR:

• Nitrates and diuretics reduce filling pressures 2
• Sodium nitroprusside reduces afterload and regurgitant fraction 2
• Intra-aortic balloon pump should be added for hemodynamic support 2
• Inotropic agents are indicated in cases of hypotension 2

Surveillance and Follow-up

For asymptomatic patients with severe MR not meeting surgical criteria:

• Clinical and echocardiographic evaluation every 6-12 months 1
• BNP monitoring may guide timing of intervention 1

For moderate MR:

• Annual echocardiography 1

For mild MR:

• Monitoring every 3-5 years 1

Critical Pitfalls to Avoid

The most common reason patients do not receive appropriate surgery is that MR is not addressed by the treating physician and patients are lost to clinical follow-up. 7

• Over 50% of patients not receiving surgery have at least one guideline indication for intervention 7
• Less than half of patients with moderate-severe and severe primary MR receive surgery in contemporary practice, and many are not even referred for surgical consultation 7
• Do not delay intervention in symptomatic patients or those with high-risk features, as irreversible pulmonary hypertension and RV dysfunction develop rapidly 8
• Lower LVESD thresholds (≥40 mm vs ≥45 mm) should be used to trigger surgery, as waiting for traditional cutoffs may result in irreversible LV dysfunction 2, 1

Additional Diagnostic Considerations When Needed

• Transesophageal echocardiography is indicated when TTE is non-diagnostic, for pre-surgical planning, and intraoperative imaging 1
• Cardiac MRI should be used when echocardiographic measurements are ambiguous, particularly for quantifying LV/RV function and MR severity 1
• Exercise echocardiography should be performed in asymptomatic patients to unmask symptoms or assess dynamic worsening of MR 1