What are the indications for mitral valve replacement (MVR) in patients with severe mitral regurgitation (MR)?

Indications for Mitral Valve Replacement in Severe Mitral Regurgitation

Mitral valve surgery is mandatory for symptomatic patients with chronic severe primary MR and LVEF >30%, and for asymptomatic patients with LV dysfunction (LVEF 30-60% or LVESD ≥40 mm), with repair strongly preferred over replacement when technically feasible. 1, 2

Primary Mitral Regurgitation

Class I Indications (Must Operate)

Symptomatic severe primary MR with LVEF >30%:

• Symptoms include decreased exercise tolerance, exertional dyspnea, or heart failure 2
• Severe MR defined by: vena contracta ≥0.7 cm, regurgitant volume ≥60 mL, regurgitant fraction ≥50%, or ERO ≥0.40 cm² 2
• Delaying surgery in these patients results in irreversible ventricular damage and worse outcomes 2

Asymptomatic severe primary MR with LV dysfunction:

• LVEF 30-60% and/or LVESD ≥40 mm (or ≥22 mm/m² BSA for small stature patients) 1, 2, 3
• This prevents irreversible ventricular damage and improves long-term survival 2

Concomitant surgery:

• Severe primary MR in patients undergoing cardiac surgery for other indications 1

Class IIa Indications (Reasonable to Operate)

Asymptomatic severe primary MR with preserved LV function (LVEF >60%, LVESD <40 mm) when:

• Likelihood of successful durable repair >95% with mortality <1% at a Heart Valve Center of Excellence 1
• New-onset atrial fibrillation develops 1, 3
• Resting pulmonary hypertension present (PA systolic pressure >50 mmHg) 1, 3

Moderate primary MR:

• When undergoing cardiac surgery for other indications 1, 3

Class IIb Indications (May Consider)

• Symptomatic severe primary MR with LVEF ≤30% 1
• Transcatheter mitral valve repair for severely symptomatic patients (NYHA III-IV) with prohibitive surgical risk despite optimal medical therapy 1

Secondary (Functional) Mitral Regurgitation

The approach to secondary MR differs fundamentally from primary MR, with medical optimization required before any surgical consideration. 2, 3

Mandatory Pre-Surgical Steps

Optimize medical therapy first:

• ACE inhibitors/ARBs, beta-blockers, and aldosterone antagonists 2, 3
• Cardiac resynchronization therapy if device indications met 2, 3
• Reassess MR severity after optimization, as it may improve significantly 3

Class I Indications

Concomitant surgery during CABG:

• Severe secondary MR in patients undergoing CABG with LVEF >30% 2, 3

Class IIa Indications

• Severe secondary MR during other cardiac surgery with LVEF >30% 1

Class IIb Indications

Isolated mitral valve surgery:

• Severely symptomatic patients (NYHA III-IV) with persistent symptoms despite optimal medical therapy 2, 3
• This is a weak recommendation as 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. 1, 2, 3

Repair Mandatory

• Primary MR limited to posterior leaflet 1, 3

Repair Preferred

• Anterior leaflet or bileaflet involvement when successful, durable repair is possible 1, 3

Echocardiographic Predictors Favoring Repair

• Chordal length >29 mm 4
• Posterior mitral leaflet length >17 mm 4
• Anterior leaflet length >25 mm 4
• Mitral annulus size >35 mm 4

Factors Favoring Replacement

• Anterior mitral annular calcification 4
• Age >63 years 4
• For secondary MR, the choice between repair and replacement remains controversial with no clear survival advantage for either approach 2

Common Pitfalls to Avoid

Do not delay surgery in symptomatic severe primary MR with preserved LVEF waiting for symptoms to worsen or LVEF to decline—this causes irreversible ventricular damage. 2

Do not perform isolated mitral surgery for secondary MR without first optimizing medical therapy including CRT if indicated. 2, 3

Do not apply primary MR surgical indications to secondary MR—the pathophysiology and surgical indications are fundamentally different. 2