When is valve replacement surgery indicated for a patient with congestive heart disease (CHD) and significant mitral regurgitation?

Surgical Indications for Mitral Valve Replacement in Congestive Heart Disease with Mitral Regurgitation

Surgery is indicated for symptomatic patients with severe mitral regurgitation and LVEF >30%, and for asymptomatic patients with LV dysfunction (LVEF 30-60% or LVESD ≥40 mm), with mitral valve repair strongly preferred over replacement when technically feasible. 1

Primary vs Secondary Mitral Regurgitation: Critical Distinction

The surgical approach differs fundamentally based on whether the mitral regurgitation is primary (organic valve disease) or secondary (functional, due to ventricular dysfunction):

Primary Mitral Regurgitation

Symptomatic Patients:

• Surgery is mandatory for all symptomatic patients with severe primary MR and LVEF >30% (Class I recommendation) 1, 2
• Symptoms include decreased exercise tolerance, exertional dyspnea, or heart failure 2
• Severe MR is defined by: vena contracta ≥0.7 cm, regurgitant volume ≥60 mL, regurgitant fraction ≥50%, or ERO ≥0.40 cm² 2
• Even patients with LVEF 30% or slightly below may be considered if they remain refractory to medical therapy 3

Asymptomatic Patients with LV Dysfunction:

• Surgery is required when LVEF falls to 30-60% and/or LVESD ≥40 mm to prevent irreversible ventricular damage 1, 2
• This represents the critical threshold where compensatory mechanisms fail and myocardial damage becomes irreversible 3, 4
• Delaying surgery beyond these thresholds results in worse long-term outcomes and persistent heart failure even after correction 4, 5
• For patients of small stature, adjust LVESD threshold to 22 mm/m² body surface area 3

Asymptomatic Patients with Preserved LV Function:

• Surgery is reasonable when new-onset atrial fibrillation develops 1, 3
• Surgery is reasonable when resting pulmonary hypertension (PA systolic pressure >50 mmHg) is present 1, 3
• At experienced centers with >95% repair success and <1% mortality, early surgery may be considered even without these triggers 1

Secondary (Functional) Mitral Regurgitation

The surgical indications are much weaker for secondary MR and require a different approach:

Medical Optimization First:

• All patients must receive optimal guideline-directed medical therapy before considering surgery, including ACE inhibitors/ARBs, beta-blockers, and aldosterone antagonists 2, 3
• Cardiac resynchronization therapy must be implemented if the patient meets device indications 2, 3
• Reassess MR severity after medical optimization, as it may improve significantly 2

Surgical Indications:

• Surgery is indicated when severe secondary MR is present in patients already undergoing CABG with LVEF >30% (Class I recommendation) 1, 2
• Isolated mitral valve surgery may be considered for severely symptomatic patients (NYHA III-IV) who remain symptomatic despite optimal medical therapy, but this is a weaker recommendation (Class IIb) 2, 3
• There is no proven survival benefit from isolated valve intervention for secondary MR 2

Repair vs Replacement Decision

Mitral valve repair is strongly preferred over replacement in all scenarios where durable repair is achievable:

• Repair is mandatory when primary MR is limited to the posterior leaflet 1, 2
• Repair is preferred for anterior leaflet or bileaflet involvement when successful, durable repair is possible 1, 2
• Repair preserves the mitral valve apparatus and left ventricular geometry, maintaining better LV function compared to replacement 6, 5
• Valve repair provides superior overall survival (68% vs 52% at 10 years), lower operative mortality (2.6% vs 10.3%), and better preserved ejection fraction compared to replacement 5
• For secondary MR, the choice between repair and replacement remains controversial with no clear survival advantage for either approach 2

Common Pitfalls to Avoid

Delaying surgery in primary MR:

• Waiting for symptoms to worsen or LVEF to decline results in irreversible ventricular damage 2, 4
• Postoperative congestive heart failure occurs in 23% at 5 years and 37% at 14 years, with dismal survival (44% at 5 years) once heart failure develops 4
• The main determinant of postoperative heart failure is decreased LV function preoperatively 4

Operating on secondary MR without medical optimization:

• Isolated mitral surgery for secondary MR without optimizing medical therapy and CRT (if indicated) has no proven benefit 2, 3
• Secondary MR may improve substantially with optimal heart failure therapy alone 2

Choosing replacement over repair:

• Replacement interrupts the annulus-papillary muscle continuity, adversely affecting LV systolic function 6
• Repair maintains LV geometry and decreases wall stress, improving survival 6, 5

Concomitant Surgery

When patients require cardiac surgery for other indications:

• Concomitant mitral valve repair or replacement is indicated for severe primary MR 1
• Concomitant repair is reasonable even for moderate primary MR 1
• For severe secondary MR with LVEF >30%, concomitant surgery is indicated during CABG 1, 3