How should I treat a symptomatic patient with severe mitral regurgitation, left ventricular end‑systolic dimension >40 mm and ejection fraction ≤60%, taking into account primary (degenerative) versus secondary (functional) etiology?

Treatment of Symptomatic Severe Mitral Regurgitation with LV Dysfunction

For a symptomatic patient with severe mitral regurgitation, LVESD >40 mm, and LVEF ≤60%, mitral valve surgery is strongly recommended regardless of whether the etiology is primary (degenerative) or secondary (functional), with mitral valve repair preferred over replacement whenever technically feasible. 1

Primary (Degenerative) Mitral Regurgitation

Class I Surgical Indication

• Mitral valve surgery is a Class I recommendation (highest level) for symptomatic patients with chronic severe primary MR and LVEF >30%. 1
• Your patient with LVEF ≤60% and LVESD >40 mm has already developed left ventricular systolic dysfunction—this represents stage C2 disease and mandates surgical intervention even if asymptomatic. 1
• The presence of symptoms elevates this to stage D disease, making surgery even more urgent. 1, 2

Repair vs. Replacement Decision

• Mitral valve repair is strongly preferred over replacement (Class I recommendation) because it preserves LV function, avoids prosthetic complications, and improves long-term survival. 1
• For posterior leaflet pathology, repair success rates exceed 90% at experienced centers. 1, 3
• For anterior leaflet or bileaflet involvement, repair is still preferred when a successful and durable repair can be accomplished. 1

Timing Considerations

• Surgery should be performed within 2 months once guideline indications are met, as even mild symptoms at the time of surgery are associated with worse cardiac function postoperatively. 1
• Delaying surgery perpetuates the "MR begets MR" cycle—progressive LV dilation increases mitral apparatus stress, causing more severe MR and further dilation, leading to irreversible LV dysfunction. 1

Critical Pitfall

• Patients who reach LVEF ≤60% or LVESD ≥40 mm have already developed LV systolic dysfunction; waiting for further deterioration results in irreversible myocardial damage and worse outcomes. 1, 3
• One study demonstrated that for LV function to normalize after repair, preoperative LVEF should be >64% and LVESD <37 mm—your patient has already exceeded these thresholds. 1

Secondary (Functional) Mitral Regurgitation

Initial Management Strategy

• Guideline-directed medical therapy (GDMT) for heart failure must be optimized first, including ACE inhibitors/ARBs, beta-blockers, aldosterone antagonists, and cardiac resynchronization therapy if indicated (Class I recommendation). 1
• All therapeutic decisions should be made by a multidisciplinary heart team. 1

Surgical Indications

• For ischemic secondary MR: Concomitant mitral valve surgery (repair or replacement) is reasonable (Class IIa) in patients undergoing CABG. 1
• For ventricular secondary MR: Surgery may be considered (Class IIb) if severe symptoms persist despite optimal GDMT and the patient is appropriate for surgery. 1
• The evidence for isolated mitral surgery in secondary MR is weaker than for primary MR because MR is only one component of the underlying myocardial disease, and restoration of valve competence does not cure the LV dysfunction. 1

Key Distinction from Primary MR

• In secondary MR, the mitral leaflets and chords are structurally normal—the regurgitation results from papillary muscle displacement and annular dilation due to LV remodeling. 1, 4
• Doppler methods may underestimate severity because the regurgitant orifice is crescentic rather than circular; integrate clinical and echocardiographic findings carefully. 1
• Even mild secondary MR portends worse prognosis independent of LV volumes and other risk factors. 5

Treatment Algorithm for Secondary MR

1. Optimize GDMT and consider cardiac resynchronization therapy 1, 5
2. For ischemic etiology: Evaluate for revascularization (CABG); if indicated, perform concomitant mitral surgery for moderate-to-severe MR 1, 5
3. For persistent severe symptomatic MR despite optimal medical therapy: Consider mitral surgery if surgical risk is acceptable 1
4. For high/prohibitive surgical risk: Consider transcatheter edge-to-edge repair (TEER) if LVEF 20-50%, LVESD ≤70 mm, and pulmonary artery systolic pressure ≤70 mm Hg 1

Transcatheter Options

For Primary MR

• Transcatheter mitral valve repair (TEER) may be considered (Class IIa in ACC/AHA, Class IIb in ESC/EACTS) for severely symptomatic patients with favorable anatomy who have prohibitive surgical risk. 1

For Secondary MR

• TEER is reasonable (Class IIa) for symptomatic patients despite optimal GDMT who are not surgical candidates, with LVEF 20-50%, LVESD ≤70 mm, and appropriate anatomy. 1

Center of Excellence Requirement

• Mitral valve surgery should be performed at a comprehensive Heart Valve Center of Excellence with repair success rates >95% and expected mortality <1%. 1, 2
• Outcomes are superior at high-volume centers with expertise in complex valve repair. 2, 3

Special Consideration: LVEF ≤30%

• For symptomatic severe primary MR with LVEF ≤30% (stage D), surgery may be considered (Class IIb) if there is high likelihood of durable repair and low comorbidity. 1
• For secondary MR with severe LV dysfunction, surgical benefit depends on whether myocardial dysfunction can be reversed (e.g., through revascularization of viable/hibernating myocardium). 6