Medical Management of Severe Mitral Regurgitation
Guideline-directed medical therapy (GDMT) is the mandatory first-line treatment for all patients with severe secondary mitral regurgitation, while severe primary mitral regurgitation has no established role for medical therapy and requires surgical intervention when symptomatic or when left ventricular dysfunction develops. 1, 2
Primary (Degenerative) Mitral Regurgitation
Limited Role for Medical Therapy
There is no well-defined role for medical therapy in chronic primary mitral regurgitation. 3 The goal is to identify the optimal timing for surgical intervention rather than to manage medically. 4, 3
Medical therapy in primary MR may temporarily improve symptoms and delay surgical intervention in select patients who are not surgical candidates, but it does not alter the disease trajectory. 5
Beta-blockers appear to lessen MR severity, prevent deterioration of left ventricular function, and improve survival in asymptomatic patients with moderate to severe primary MR. 5 This is the strongest evidence for any medical therapy in primary MR.
ACE inhibitors and ARBs reduce MR severity, especially in asymptomatic patients with primary MR. 5
Critical Caveat for Vasodilators
- In patients with hypertrophic cardiomyopathy or mitral valve prolapse, vasodilators can paradoxically increase the severity of MR and should be avoided. 5 This occurs because reducing afterload increases the dynamic component of obstruction and worsens regurgitation.
Secondary (Functional) Mitral Regurgitation
Mandatory Optimization Before Intervention
Patients must be on optimally tolerated doses of guideline-directed medical therapy before being labeled as having severe secondary MR or considered for intervention. 6 The severity of secondary MR is highly dynamic and changes dramatically with medical optimization. 6
Core Medical Therapy Components
ACE inhibitors or ARBs are first-line therapy for all patients with secondary MR and should be uptitrated to maximally tolerated doses. 1, 2 These agents reduce MR severity by decreasing afterload and promoting reverse LV remodeling. 6, 7
Beta-blockers prevent LV deterioration and are essential components of GDMT. 1, 2 They should be titrated to target doses used in heart failure trials.
Mineralocorticoid receptor antagonists (spironolactone or eplerenone) are recommended as part of comprehensive GDMT. 1, 2
Diuretics are first-line for fluid overload manifestations such as lower extremity edema and pulmonary congestion. 2 Loop diuretics should be titrated to achieve euvolemia.
Nitrates may be useful for acute dyspnea in patients with a large dynamic component of MR, particularly during hypertensive episodes or acute decompensation. 2
Rapid Medication Titration Protocol
Rapid medication titration protocols reduce heart failure hospitalization and facilitate earlier referral for device therapy. 7 Optimal medical therapy has been shown to reduce the severity of mitral regurgitation in 40-45% of patients with secondary MR. 7
The dynamic nature of secondary MR means that EROA can decrease from 0.35 cm² to 0.15 cm² within one month of optimizing medical therapy, converting "severe" MR to moderate. 6
Cardiac Resynchronization Therapy
- CRT should be implemented in patients who meet guideline-directed criteria (typically LVEF ≤35%, QRS ≥150 ms, LBBB pattern). 6, 1, 2 CRT reduces MR severity through improved ventricular synchrony and reverse remodeling. 6, 7
Rhythm Management
- The pursuit of sinus rhythm in patients with atrial fibrillation significantly reduces mitral regurgitation severity. 7 Atrial fibrillation causes loss of the "Venturi effect" during atrial relaxation that normally aids in leaflet coaptation. 6
When Medical Therapy Alone Is Insufficient
For Secondary MR
Transcatheter edge-to-edge repair (TEER) should be considered for patients with severe secondary MR, LVEF 20-50%, LV end-systolic diameter ≤70 mm, and persistent NYHA class II-IV symptoms despite optimal medical therapy and CRT when indicated. 6, 1, 2
Patients must have at least one heart failure hospitalization within the previous year or elevated natriuretic peptide levels to qualify for TEER. 6
Mitral valve surgery is indicated when severe secondary MR is present and the patient is undergoing coronary artery bypass grafting with LVEF >30%. 2 However, surgery purely to address secondary MR carries only a Class IIb recommendation because evidence has not shown mortality benefit. 6
For Primary MR
Surgery is indicated for all symptomatic patients with severe primary MR regardless of left ventricular function. 1, 2
Surgery is indicated in asymptomatic patients when LVEF falls to ≤60% or LV end-systolic diameter reaches ≥40 mm. 6, 2 These thresholds may already indicate LV dysfunction, so earlier intervention is reasonable when serial imaging shows progressive LV dilation or declining LVEF approaching these thresholds. 6
Surveillance Requirements During Medical Management
Asymptomatic severe MR requires clinical and echocardiographic follow-up every 6-12 months. 6, 1, 2
Moderate MR requires clinical evaluation every 6-12 months with annual echocardiography. 1, 2
Serum biomarkers (BNP or NT-proBNP) may help guide optimal timing of intervention in asymptomatic patients with severe MR. 6, 2
Critical Pitfalls to Avoid
Do not proceed to intervention for secondary MR without first optimizing GDMT and considering CRT. 2 The severity assessment is invalid until medical therapy is maximized. 6
Do not delay surgery in asymptomatic primary MR once LVEF falls to ≤60% or LVESD reaches ≥40 mm. 2 These thresholds indicate incipient myocardial dysfunction that may become irreversible. 6
Do not use vasodilators in patients with mitral valve prolapse or hypertrophic cardiomyopathy, as they worsen MR severity. 5
All intervention decisions must involve multidisciplinary team discussion by the heart team, including assessment of valve morphology, MR etiology, patient comorbidities, and surgical risk. 6, 1, 2