What is the best management approach for a patient with moderate mitral regurgitation (MR)?

Management of Moderate Mitral Regurgitation

Moderate MR requires surveillance with clinical evaluation every 6-12 months and annual echocardiography, with intervention reserved for specific scenarios where the patient is undergoing concomitant cardiac surgery or develops objective evidence of cardiac decompensation. 1, 2

Initial Diagnostic Confirmation

Before committing to a surveillance strategy, confirm the diagnosis is truly moderate MR, as this distinction is critical:

• Obtain comprehensive echocardiography to verify MR severity using multiple parameters: vena contracta width, EROA, regurgitant volume, and regurgitant fraction 3
• Consider additional testing (TEE, CMR, or cardiac catheterization) when uncertainty exists between mild-to-moderate or moderate-to-severe MR 3, 1
• Distinguish primary from secondary MR, as this fundamentally changes the management algorithm 1, 2

Common Pitfalls in Severity Assessment

Color Doppler can overestimate MR severity in patients with hypertension, high LV systolic pressure, or when using single-frame measurements in non-holosystolic MR 3. Conversely, it can underestimate severity with high LA pressures, low LVEF, or large chamber volumes 3. When in doubt, use adjunctive criteria: a dense triangular continuous-wave Doppler profile, pulmonary artery systolic pressure >50 mmHg without other cause, or systolic pulmonary vein flow reversal all support more severe disease 3.

Management Algorithm for Moderate Primary MR

Asymptomatic Patients

Surveillance is the standard approach for asymptomatic moderate primary MR:

• Clinical evaluation every 6-12 months 1, 2
• Annual echocardiography to monitor for progression 1, 2
• Serial imaging to detect development of LV dysfunction (LVEF ≤60%) or LV dilation (LVESD ≥40 mm) 2
• Consider exercise echocardiography if the patient reports exercise-induced symptoms to assess for dynamic worsening 2

Surgery is NOT indicated for isolated moderate primary MR in asymptomatic patients, even with excellent valve repair feasibility 3. The guidelines identify this as a gap in evidence, with no clear data supporting prophylactic intervention 3.

Symptomatic Patients

Medical optimization first: Ensure symptoms are truly attributable to MR and not other causes (coronary disease, hypertension, arrhythmias). If symptoms persist and are clearly related to moderate MR with no other explanation, multidisciplinary heart team evaluation is warranted to assess whether intervention is appropriate 3, 1, 2.

Concomitant Cardiac Surgery

This is the primary scenario where moderate MR intervention is considered:

• MV repair may be considered at the time of coronary artery bypass grafting for patients with multivessel coronary artery disease and moderate secondary MR, though benefit remains uncertain 3
• MV repair is reasonable for moderate primary MR when the patient is undergoing other cardiac surgery (e.g., CABG, aortic valve surgery) 3
• The decision should involve the surgical team's assessment of repair feasibility, operative risk, and whether adding MV repair significantly increases procedural complexity 3

Historical data suggests that leaving moderate ischemic MR unaddressed at the time of CABG results in approximately 40% of patients having persistent moderate-to-severe MR postoperatively 4. However, more recent guidelines remain cautious about routine intervention given the lack of definitive mortality benefit 3.

Management Algorithm for Moderate Secondary MR

First-Line: Guideline-Directed Medical Therapy (GDMT)

GDMT is mandatory and must be maximized before any consideration of intervention 1, 2:

• ACE inhibitors or ARBs as first-line therapy 1, 2
• Beta-blockers to prevent LV deterioration 1
• Mineralocorticoid receptor antagonists (spironolactone or eplerenone) 1, 2
• Diuretics for fluid overload manifestations such as lower extremity edema 2
• Nitrates may be useful for acute dyspnea in patients with a large dynamic component of MR 2

Cardiac Resynchronization Therapy (CRT)

Implement CRT in patients meeting guideline criteria (typically LVEF ≤35%, QRS ≥150 ms with LBBB morphology) before considering any valve intervention 1, 2. CRT can reduce MR severity by improving ventricular synchrony and reducing mitral annular dilation 3.

Surveillance Strategy

• Clinical evaluation every 6-12 months with annual echocardiography 1, 2
• Monitor for progression to severe MR (EROA ≥0.3-0.4 cm²) 3, 1
• Assess for development of symptoms despite optimal medical therapy 1, 2
• Consider BNP/NT-proBNP monitoring to guide timing of intervention 3, 2

Intervention Considerations

For moderate secondary MR, intervention is generally NOT indicated unless:

1. The patient is undergoing CABG with multivessel disease and LVEF >30%, where MV repair with a downsized annuloplasty ring may be considered 3
2. The patient has atrial functional MR with annular dilatation and persistent/long-standing persistent atrial fibrillation requiring other cardiac surgery 3

Transcatheter edge-to-edge repair (TEER) is NOT indicated for moderate secondary MR; it is reserved for severe secondary MR with persistent NYHA class II-IV symptoms despite optimal GDMT and CRT 3, 1, 2.

Critical Clinical Pearls

Do not proceed to intervention without:

• Confirming MR severity with comprehensive multiparametric echocardiographic assessment 3
• Distinguishing primary from secondary etiology 1, 2
• Maximizing GDMT for secondary MR 1, 2
• Multidisciplinary heart team discussion when intervention is being considered 3, 1, 2

Recognize that moderate MR is a surveillance diagnosis, not an intervention indication, except in the specific context of concomitant cardiac surgery where the risk-benefit calculation changes 3.