How should moderate mitral regurgitation be managed in an asymptomatic patient with preserved left ventricular ejection fraction, normal left ventricular end‑systolic dimension, and no pulmonary hypertension?

Management of Moderate Mitral Regurgitation

Asymptomatic patients with moderate mitral regurgitation, preserved left ventricular function, and no pulmonary hypertension should be managed conservatively with regular surveillance—surgery is not indicated at this stage. 1

Conservative Management Strategy

Clinical Surveillance Protocol

Follow-up schedule for moderate MR with preserved LV function:

• Clinical visits annually to assess for symptom development 1
• Echocardiography every 2 years to monitor LV size and function, MR severity, and pulmonary artery pressures 1
• Patients must be instructed to report immediately any change in functional status, particularly dyspnea or decreased exercise tolerance 1

This represents the standard approach from European guidelines, which explicitly state that asymptomatic patients with moderate MR and preserved LV function can be followed clinically on a yearly basis with echocardiography every 2 years. 1

Key Parameters to Monitor on Serial Echocardiography

Critical thresholds that trigger escalation to more frequent monitoring or surgical referral:

• Left ventricular ejection fraction: Watch for decline toward 60% or below 2
• LV end-systolic dimension: Intervention threshold is ≥40 mm 1, 2
• Pulmonary artery systolic pressure: Resting pressure >50 mmHg warrants surgical consideration 2, 3
• Left atrial volume index: Severe enlargement (≥60 mL/m²) indicates advanced remodeling and may warrant earlier intervention 2, 3
• Progression of MR severity: Advancement to severe MR changes management completely 2
• Development of atrial fibrillation: New-onset AF is a trigger for surgical evaluation 2

Medical Therapy Considerations

No specific vasodilator therapy is recommended for organic (primary) mitral regurgitation with preserved LV function. 1 The European guidelines explicitly state that long-term vasodilator therapy is not recommended in patients with organic MR and should not delay surgery if indicated. 1

However, there are important nuances:

• If hypertension is present, it should be controlled as it can affect MR severity 2
• Recent observational data suggest ACE inhibitors or ARBs may provide benefit in patients with moderate-to-severe MR and preserved ejection fraction, showing reduced risk of death and heart failure hospitalization 4
• Beta-blockers may lessen MR severity and prevent LV dysfunction deterioration in some patients 5

Anticoagulation is indicated (INR 2.5-3.5) if the patient develops atrial fibrillation (permanent or paroxysmal), has a history of systemic embolism, or has evidence of left atrial thrombus. 1

When Surgery Becomes Indicated

Surgery is NOT indicated for moderate MR with your current parameters. 2, 6 Intervention would only be considered if:

Absolute Indications for Surgical Referral

• MR progresses to severe AND patient becomes symptomatic (NYHA Class II-IV) 2
• LVEF decreases to <60% with LV end-systolic dimension ≥40 mm 2
• New-onset atrial fibrillation secondary to MR 2
• Resting pulmonary artery systolic pressure exceeds 50 mmHg 2, 3
• Progressive LV dilation on serial imaging 2
• LA volume index reaches ≥60 mL/m² (particularly if repair can be performed at high-volume center with >95% repair success and <1% mortality) 2, 3

Special Circumstance

If the patient requires cardiac surgery for another indication (e.g., coronary artery bypass), concomitant mitral valve repair may be considered even for moderate MR. 2, 6, 3

Important Clinical Pitfalls

Eccentric Jets May Underestimate Severity

• Standard color Doppler techniques may underestimate MR severity when jets are eccentric 2
• Consider transesophageal echocardiography for more accurate assessment if there is clinical-echocardiographic discordance 2
• Cardiovascular magnetic resonance may be valuable if echocardiographic assessment is inconclusive 2

Exercise Testing for Symptom Clarification

• Stress echocardiography should be considered if there is discrepancy between symptoms and resting findings, as MR severity may increase with exercise 2
• This is particularly useful in patients who report symptoms but appear to have only moderate MR at rest 1

Risk of Progression Despite "Moderate" Classification

• Over 50% of patients with less-than-severe MR develop either worsening regurgitation or new LV dysfunction during long-term follow-up 7
• LV deterioration can occur even without MR progression in 21% of patients with stable regurgitation 7
• This underscores the critical importance of regular surveillance rather than assuming stability 7

When Repair is Preferred Over Replacement

• Mitral valve repair is strongly preferred over replacement when intervention eventually becomes necessary, as it preserves LV function and avoids prosthetic valve complications 2, 6