When is surgical intervention recommended for patients with severe mitral regurgitation?

Timing of Surgery in Mitral Regurgitation

Primary Mitral Regurgitation: Symptomatic Patients

Surgery is mandatory for all symptomatic patients with severe primary mitral regurgitation and LVEF >30%, regardless of the degree of left ventricular dysfunction (Class I recommendation). 1, 2

• Symptoms include decreased exercise tolerance, exertional dyspnea, or heart failure manifestations. 3
• Mitral valve repair is strongly preferred over replacement when technically feasible, particularly for degenerative disease involving the posterior leaflet where success rates exceed 90% in experienced centers. 1, 2, 4
• Even patients with LVEF between 30-60% should undergo surgery when symptomatic, as this prevents irreversible cardiac damage and improves survival. 2
• For patients with LVEF <30%, surgery may still be considered if they remain refractory to medical therapy, but only when there is high likelihood of durable repair and low comorbidity. 2

Critical pitfall: Delaying surgery in symptomatic patients—even those with mild symptoms (NYHA class II)—leads to progressive left ventricular dysfunction, left atrial enlargement, atrial fibrillation, and tricuspid regurgitation, all of which worsen surgical outcomes and long-term survival. 5, 6

Primary Mitral Regurgitation: Asymptomatic Patients with LV Dysfunction

Surgery is indicated for asymptomatic patients who develop LV dysfunction defined as LVEF ≤60% and/or LVESD ≥40 mm (Class I recommendation). 1, 2

• This represents a critical threshold where compensatory mechanisms begin to fail and irreversible myocardial damage occurs. 2
• The LVESD threshold of 40 mm should be adjusted downward to 22 mm/m² body surface area in patients of small stature. 2, 3
• An LVEF of 60% in severe mitral regurgitation actually represents early myocardial dysfunction, as the load-dependent measure masks true contractile impairment; normal LVEF in severe MR should be >64%. 4
• Early surgery at these thresholds (within 2 months of meeting criteria) is associated with better outcomes than delayed intervention. 2
• Preoperative echocardiographic ejection fraction is the most powerful predictor of late survival, with 10-year survival of 72% for EF ≥60%, 53% for EF 50-60%, and only 32% for EF <50%. 6

Primary Mitral Regurgitation: Asymptomatic Patients with Preserved LV Function

Surgery should be considered in asymptomatic patients with preserved LV function when specific high-risk features develop (Class IIa recommendations). 2

Key triggers for surgical intervention include:

• New-onset atrial fibrillation warrants surgical consideration as it indicates progressive left atrial remodeling. 2, 3
• Pulmonary hypertension with systolic pulmonary artery pressure >50 mmHg at rest. 2, 3
• Flail leaflet with LVESD ≥40 mm. 2

The decision for early prophylactic surgery in asymptomatic patients without these triggers hinges on the likelihood of successful mitral valve repair. 7

• In centers with high repair success rates (>90%) and low operative mortality (<1%), early surgery is reasonable even without objective triggers, as repair rates decline from 96% in asymptomatic patients to 85% in NYHA class IV patients. 5
• Operative mortality in experienced centers is now 1.1% in patients younger than 75 years, making early intervention increasingly favorable. 6

Secondary Mitral Regurgitation

Surgery or intervention for secondary mitral regurgitation should only be considered in symptomatic patients who remain symptomatic despite optimal guideline-directed medical therapy, including cardiac resynchronization therapy if indicated (Class I recommendation). 1, 2

The approach differs fundamentally from primary MR:

• Medical optimization is mandatory before considering surgery, including ACE inhibitors/ARBs, beta-blockers, and aldosterone antagonists. 3
• Cardiac resynchronization therapy must be implemented if the patient meets device indications. 3
• Reassess MR severity after medical optimization, as it may improve significantly. 3

For patients undergoing coronary artery bypass grafting with LVEF >30%, concomitant mitral valve surgery is indicated when severe secondary mitral regurgitation is present. 1, 2, 3

• Isolated mitral valve surgery for secondary MR carries only a Class IIb recommendation (may be considered) in severely symptomatic patients (NYHA III-IV) who remain symptomatic despite optimal medical therapy. 3

Transcatheter Options

Transcatheter edge-to-edge repair (TEER) may be considered as an alternative to surgery only in symptomatic patients with severe primary mitral regurgitation who are at high or prohibitive surgical risk and have favorable anatomy. 1, 2

For primary MR, TEER is reasonable when:

• LVEF is 20-50% 2
• LVESD ≤70 mm 2
• Pulmonary artery systolic pressure ≤70 mmHg 2

For secondary mitral regurgitation, TEER should be considered in symptomatic patients meeting COAPT criteria who remain symptomatic after optimal medical therapy (Class IIa-B recommendation). 1, 2

Monitoring Strategy for Asymptomatic Patients

Asymptomatic severe mitral regurgitation requires follow-up every 6-12 months with echocardiography. 2

• Asymptomatic moderate mitral regurgitation with preserved LV function requires yearly clinical follow-up with echocardiography every 1-2 years. 2
• More frequent reassessment is needed if progressive LV dilation is occurring. 2
• Consider exercise echocardiography, Holter monitoring, and cardiac MRI for risk stratification in borderline cases. 2

Critical pitfall: Waiting for symptoms to develop or EF to decline further results in irreversible LV dysfunction and worse outcomes, with the development of even mild symptoms associated with deleterious changes in cardiac structure and function. 4, 5