What is the clinical management for severe mitral regurgitation?

Clinical Management of Severe Mitral Regurgitation

The management of severe mitral regurgitation requires a structured approach based on whether the condition is primary (valve abnormality) or secondary (dysfunction of surrounding structures), with surgical intervention indicated for symptomatic patients with severe primary MR and optimal medical therapy as the first step for all patients with secondary MR. 1, 2

Initial Assessment and Classification

• Echocardiography is essential to determine whether mitral regurgitation is primary or secondary, guiding subsequent management decisions 2
• Severe MR is defined by vena contracta ≥7 mm, effective regurgitant orifice area (EROA) ≥0.4 cm² for primary MR, regurgitant fraction (RF) ≥50%, and regurgitant volume (RVol) ≥60 mL/beat 1
• For secondary MR, thresholds may differ with EROA ≥0.3 cm² if the regurgitant orifice is elliptical in nature 1
• Exercise echocardiography should be considered when exercise-induced symptoms are present to assess for dynamic worsening of MR 2
• Cardiovascular magnetic resonance (CMR) can be used to quantify LV/RV function, chamber size, and MR severity when echocardiographic measurements are ambiguous 1

Medical Management

• Diuretics are first-line therapy for patients with fluid overload manifestations such as lower extremity edema 2
• Guideline-directed medical therapy (GDMT) including ACE inhibitors, beta-blockers, and aldosterone antagonists is mandatory as the first step for all patients with secondary MR 2, 3
• Optimal medical therapy has been shown to reduce the severity of secondary MR in 40-45% of patients 3
• Nitrates may be useful for treating acute dyspnea in patients with a large dynamic component of MR 2
• Management of atrial fibrillation with rhythm control strategies can significantly reduce MR severity 3

Surgical Management for Primary MR

• Surgery is indicated for symptomatic patients with severe primary MR, regardless of left ventricular function 1, 2
• Mitral valve repair is strongly preferred over replacement when technically feasible 2
• For asymptomatic severe primary MR, surgical intervention is indicated when:
  • LVEF ≤60% and/or LV end-systolic dimension (LVESD) ≥40 mm 1
  • New-onset atrial fibrillation or pulmonary artery systolic pressure >50 mmHg 1
• Delaying surgical intervention until symptoms become severe or left ventricular dysfunction occurs can lead to worse outcomes 2

Management of Secondary MR

• Optimal medical therapy must be maximized before considering interventional approaches 2
• Cardiac resynchronization therapy (CRT) should be considered in appropriate candidates as it may reduce MR severity through increased closing force and resynchronization of papillary muscles 2, 3
• Surgery is indicated in patients with severe secondary MR undergoing coronary artery bypass grafting and LVEF >30% 2
• For patients who remain symptomatic despite optimal GDMT:
  • Transcatheter edge-to-edge repair (TEER) should be considered in patients who are inoperable or at high surgical risk 2, 3
  • The number needed to treat with TEER is 3.1 to reduce heart failure hospitalization and 5.9 to reduce all-cause death 3

Surveillance and Follow-up

• Asymptomatic severe MR requires follow-up every 6 to 12 months 1, 2
• Patients with moderate MR should have clinical evaluation every 6-12 months with annual echocardiography 2
• Patients with mild MR should be monitored every 3-5 years 1
• Serum biomarkers (e.g., BNP) may be helpful to guide optimal timing of intervention in asymptomatic patients with severe MR 1

Multidisciplinary Approach

• All guidelines strongly emphasize multidisciplinary team (MDT) discussion by the heart team to guide optimal intervention 1
• The heart team should consider the morphology of the mitral valve, MR etiology, patient comorbidities, and surgical risk 1
• Preoperative risk stratification should include assessment of:
  • STS-PROM score
  • Frailty
  • Organ system compromise
  • Procedure-specific impediments 1

Common Pitfalls and Considerations

• Failing to recognize the dynamic nature of secondary MR can lead to inappropriate management decisions 2
• Different thresholds for severe secondary MR across guidelines (EROA ≥0.4 cm² vs. ≥0.3 cm² vs. ≥0.2 cm²) can impact patient selection for intervention 1
• The severity of secondary MR should be reassessed after optimized medical treatment before deciding on intervention 2
• For patients with mixed valvular disease, a thorough Heart Valve Team evaluation is essential due to limited evidence in this area 1

By following this structured approach to the management of severe mitral regurgitation, clinicians can optimize outcomes by selecting the most appropriate interventions based on MR etiology, patient characteristics, and response to medical therapy.