For an adult with symptomatic primary mitral regurgitation and left ventricular ejection fraction ≤60% or end‑systolic dimension ≥40 mm, when should an Alfieri edge‑to‑edge mitral‑valve repair be performed, what technical requirements (annuloplasty ring, residual orifice ≥2 cm²) must be met, and when is mitral‑valve replacement indicated?

Alfieri Mitral Valve Repair (Edge-to-Edge Repair)

Timing of Intervention

For adults with symptomatic primary mitral regurgitation and LVEF ≤60% or LVESD ≥40 mm, mitral valve surgery is indicated immediately, with repair strongly preferred over replacement. 1, 2, 3

Symptomatic Patients with LV Dysfunction

• Surgery is a Class I indication for all symptomatic patients with severe primary MR when LVEF is between 30-60% and/or LVESD ≥40 mm. 1, 2
• These patients have already developed LV systolic dysfunction, and delaying surgery leads to irreversible myocardial damage and worse long-term survival. 1, 4
• Even patients with LVEF as low as 30% should undergo surgery if symptomatic, as this improves survival and prevents further deterioration. 2, 3

Symptomatic Patients with Preserved LV Function

• Surgery should be performed in patients with mild symptoms (NYHA Class II) and severe MR when LVEF >60% and LVESD <40 mm, especially if repair is feasible. 1
• The presence of symptoms alone with severe MR is sufficient indication for intervention, regardless of LV parameters. 1, 2

Asymptomatic Patients

• Surgery is indicated for asymptomatic patients once LVEF falls to ≤60% or LVESD reaches ≥40 mm (Class I indication). 1, 2, 3
• These thresholds represent the point where compensatory mechanisms fail and irreversible damage begins. 1, 2
• For patients of small stature, adjust the LVESD threshold downward to 22 mm/m² body surface area. 2
• Surgery should be considered earlier (Class IIa) when serial imaging shows progressive LV dilation or declining EF approaching these thresholds. 1
• Additional Class IIa indications in asymptomatic patients with preserved LV function include new-onset atrial fibrillation or resting pulmonary hypertension (PASP >50 mmHg). 1, 2, 3

Technical Requirements for Alfieri/Edge-to-Edge Repair

Surgical Edge-to-Edge Repair

• Mitral valve repair is strongly preferred over replacement (Class I recommendation) when a successful and durable repair can be achieved. 1, 2, 3
• Repair is particularly favored for posterior leaflet pathology, where success rates exceed 95%. 1
• For anterior leaflet or bileaflet involvement, repair is still preferred when a durable repair is achievable. 1
• Annuloplasty ring placement is typically required with edge-to-edge repair to ensure durability and prevent recurrent MR. 3
• The residual mitral valve orifice area should be ≥2 cm² to avoid iatrogenic mitral stenosis, though specific guidelines do not mandate this exact threshold. 1

Transcatheter Edge-to-Edge Repair (TEER/MitraClip)

• TEER should only be considered in symptomatic patients with severe primary MR who are at high or prohibitive surgical risk and have favorable anatomy. 2, 3
• Anatomic criteria for TEER include LVEF 20-50%, LVESD ≤70 mm, and PASP ≤70 mmHg. 2, 3
• An independent eligibility assessment should confirm that MR can be reduced to mild or less with high certainty. 5
• TEER is not a substitute for surgery in patients who are good surgical candidates, as surgery remains the gold standard. 2, 6

When Mitral Valve Replacement is Indicated

Primary Indications for Replacement

• Replacement should be performed only when repair is not technically feasible or when repair attempts fail. 1
• Even when replacement is necessary, chordal-sparing techniques must be used to preserve LV geometry and function. 1
• Patients with far-advanced LV dysfunction (LVEF <30%) may require replacement if repair is not possible, but only if chordal preservation can be achieved. 1

Contraindications to Repair

• Extensive calcification of the mitral apparatus that prevents adequate leaflet coaptation
• Severe leaflet destruction or retraction that cannot be reconstructed
• Rheumatic disease with severe leaflet thickening and commissural fusion (though guidelines focus on degenerative disease) 1

Critical Pitfalls to Avoid

Timing Errors

• Do not wait for LVEF to fall below 60% or LVESD to exceed 40 mm before referring symptomatic patients—these thresholds indicate existing LV dysfunction, not optimal timing. 1
• Recent evidence suggests that surgery should be considered even earlier, before LVEF falls below 65% or left atrial volume index reaches 53 mL/m², as these predict postoperative LV dysfunction and worse long-term survival. 7
• Patients with ClassI triggers (symptoms, LVEF <60%, LVESD ≥40 mm) have significantly worse 15-year survival (42%) compared to those operated earlier based on high repair probability (70% survival). 4

Referral Failures

• Over 50% of patients with guideline-based indications for surgery are not referred to cardiothoracic surgery, often because MR is not addressed by the treating physician. 8
• All patients meeting surgical criteria should be referred to experienced mitral valve centers where repair rates exceed 95% and operative mortality is <1%. 1, 2, 3

Inappropriate TEER Use

• TEER should not be offered to good surgical candidates simply because it is less invasive—surgery provides superior long-term outcomes in appropriate candidates. 2, 6
• TEER in primary MR is only appropriate for high/prohibitive surgical risk patients with favorable anatomy. 2, 3

Monitoring Strategy

• Asymptomatic severe MR requires echocardiographic follow-up every 6 months to detect early LV dysfunction. 1, 2, 3
• More frequent reassessment is needed if progressive LV dilation is occurring on serial studies. 2, 3
• Exercise echocardiography should be considered in asymptomatic patients to unmask symptoms or pulmonary hypertension. 1