What are the management parameters for severe Mitral Regurgitation (MR)?

Management Parameters for Severe Mitral Regurgitation

The management of severe mitral regurgitation (MR) requires surgical or percutaneous intervention in symptomatic patients and those with left ventricular dysfunction (LVEF ≤60%) or dilation (LVESD ≥40mm), regardless of symptoms. 1

Definition of Severe MR

Severe MR is consistently defined across guidelines by the following parameters:

• Vena contracta ≥7 mm
• Effective regurgitant orifice area (EROA) ≥0.4 cm² for primary MR
• Regurgitant volume (RVol) ≥60 mL/beat for primary MR
• Regurgitant fraction (RF) ≥50%
• Pulmonary vein systolic flow reversal
• E-wave dominant >1.2 m/s

For secondary MR, there are some variations in thresholds, with some guidelines suggesting EROA ≥0.2 cm² and RVol ≥30 mL as sufficient for severe secondary MR 1.

Surveillance Recommendations

For asymptomatic patients with severe MR:

• Clinical and echocardiographic evaluation every 6-12 months
• More frequent follow-up (every 6 months) for patients with preserved LVEF >60%
• Consider biomarkers, novel measurements of LV function (e.g., global longitudinal strain)
• Exercise echocardiography, Holter monitoring, and CMR may be useful for risk stratification

Indications for Intervention in Primary MR

Symptomatic Patients

• Surgical intervention is indicated for symptomatic severe primary MR regardless of LV function 1
• For patients with LVEF <30%, surgery may be considered if symptoms persist despite optimal medical therapy

Asymptomatic Patients

Intervention is indicated for asymptomatic severe primary MR when:

• LVEF ≤60% or LVESD ≥40 mm (Class IB recommendation) 1
• New-onset atrial fibrillation or pulmonary hypertension (PASP ≥50 mmHg) (Class IIaB) 1
• Significant left atrial dilation (LA volume index ≥60 mL/m² or diameter >55 mm) when performed at a heart valve center with high likelihood of durable repair (Class IIaB) 1
• Progressive increase in LV size or decrease in EF on ≥3 serial imaging studies (Class IIbC) 1

Indications for Intervention in Secondary MR

• Optimal medical therapy is the first-line treatment, including ACE inhibitors, ARBs, beta-blockers, and MRAs 1
• Cardiac resynchronization therapy (CRT) should be performed if indicated (Class IA) 1
• Valve surgery may be considered for symptomatic patients despite optimal medical therapy (including CRT if indicated) (Class IIbC) 1
• For patients with severe ischemic MR undergoing CABG, mitral valve surgery is reasonable (Class IIaC) 1

Choice of Intervention

Primary MR

• Mitral valve repair is strongly recommended over replacement when anatomically feasible and when a successful and durable repair is likely (Class IB) 1
• Repair should be performed at centers with high repair rates and low operative mortality
• Chordal-sparing MV replacement when repair is not feasible

Secondary MR

• For patients with LVEF >30% undergoing CABG, concomitant mitral valve surgery is recommended (Class IC) 1
• For patients with LVEF ≤30% undergoing CABG, mitral valve surgery may be considered (Class IIbC) 1
• Transcatheter edge-to-edge repair (TEER) should be considered in symptomatic patients with LVEF >30% and severe MR who have no indication for coronary revascularization after optimal medical therapy (Class IIbB) 1

Percutaneous Intervention

• TEER may be considered for symptomatic patients with high/prohibitive surgical risk when anatomy is favorable and life expectancy is at least 1 year (Class IIB) 1
• For secondary MR, TEER should be considered in patients with LVEF >30% and severe MR who remain symptomatic despite optimal medical therapy and have no indication for coronary revascularization (Class IIbB) 1

Medical Therapy

Acute MR

• Vasodilator therapy with sodium nitroprusside or nicardipine
• Inotropic support if hemodynamically unstable
• IABP for hypotension and hemodynamic instability

Chronic MR

• Standard heart failure management for secondary MR
• ACE inhibitors/ARBs, beta-blockers, and vasodilator therapy
• Consider sacubitril/valsartan, SGLT2 inhibitors, and/or ivabradine
• Coronary revascularization when indicated

Common Pitfalls and Caveats

1. Underestimating MR severity: Integrating multiple echocardiographic parameters is essential as a single parameter may be misleading.

2. Delayed intervention: Waiting until symptoms develop or LV dysfunction occurs may result in irreversible myocardial damage. Early surgical referral should be considered when repair is likely to be successful.

3. Overreliance on LVEF: LVEF is load-dependent and may remain preserved despite declining myocardial contractility. Consider additional parameters like LV dimensions and strain imaging.

4. Dynamic nature of secondary MR: Severity can change with loading conditions, ischemia, and heart rate/rhythm. Assessment should be performed under stable conditions.

5. Inappropriate patient selection for TEER: Not all patients benefit equally from percutaneous approaches. Heart team evaluation is crucial for optimal patient selection.

6. Inadequate follow-up: Asymptomatic patients with severe MR require regular surveillance to detect early signs of deterioration that would warrant intervention.