Interventions for Mitral Valve Diseases

1. Mitral Stenosis (MS)

Medical Therapy

• Rate control (beta-blockers, digoxin in AF) — prolongs diastolic filling time and reduces gradients
• Diuretics — relieve pulmonary congestion
• Anticoagulation (OAC) — mandatory in AF, prior thromboembolism, or LA thrombus; direct oral anticoagulants are not recommended in rheumatic MS
• Secondary prophylaxis for rheumatic fever in rheumatic MS (RMS)

Transcatheter Intervention: Percutaneous Balloon Mitral Valvuloplasty / Commissurotomy (BMV/PBMC)

• Symptomatic severe MS (MVA <1.5 cm²) with favourable anatomy
• May be considered with unfavourable anatomy at high surgical risk in expert centres
• Asymptomatic MS with severe pulmonary hypertension (PAH >50 mmHg) or new-onset AF with favourable anatomy
• Pregnancy with severe MS — BMV is the treatment of choice; ideally after 24 weeks gestation (superior to surgery, with minimal fetal harm)

Surgical Therapy for MS

• Open mitral commissurotomy (valve repair) — preferred when feasible
• Mitral valve replacement (MVR) — when repair is not possible (severe calcification, subvalvular disease)
• Transcatheter mitral valve replacement (TMVR) in mitral annular calcification (MAC) or failed bioprostheses — investigational/emerging

2. Primary (Organic/Degenerative) Mitral Regurgitation

Medical Therapy

• Limited role in chronic primary MR with normal LV function
• Blood pressure control is warranted (reduces MR severity)
• Vasodilators (ACE inhibitors/ARBs) show only modest reduction in regurgitant fraction (~8%) — not indicated in normotensive patients with normal LVEF
• In reduced LVEF (<60%): standard guideline-directed medical therapy (GDMT)
• Acute severe MR: IV nitroprusside (afterload reduction) ± dobutamine if hypotensive; intra-aortic balloon counterpulsation (IABP) as bridge to surgery — Braunwald's Heart Disease, p. 782

Surgical Therapy — Primary MR

• Symptomatic severe primary MR (Stage D) — surgery regardless of LV function
• Asymptomatic severe MR with LV dysfunction (LVEF <60% or LVESD >40 mm)

• Asymptomatic severe MR with preserved LV function when high likelihood of durable repair at low operative risk (<1% mortality) at a Valve Centre

• MV repair is strongly preferred over replacement when achievable — superior long-term outcomes, avoids anticoagulation (bio-prosthesis), preserves LV geometry
• MVR should not be performed for posterior leaflet pathology <½ unless repair fails at a Valve Centre
• Repair success correlates directly with surgical volume and expertise
• 20-year data show repair significantly superior to replacement for degenerative MR — Fuster and Hurst's The Heart, p. 975

• Leaflet resection (triangular/quadrangular)
• Neochordae implantation
• Annuloplasty ring (reduces annular dilation)
• Commissuroplasty
• Cleft closure, edge-to-edge (Alfieri stitch)

Transcatheter Therapy — Primary MR

• Delivered via transseptal puncture; a clip grasps the A2–P2 leaflet edges creating a double-orifice valve
• FDA-approved (2013) for severe symptomatic primary MR in high/prohibitive surgical risk patients (EVEREST II trial)
• Class IIa (ACC/AHA 2020) for non-surgical candidates with severe primary MR with symptoms or LV systolic dysfunction
• EVEREST II 5-year data showed clinical outcomes not inferior to surgery despite less complete MR reduction
• Unfavourable anatomy: perforated/calcified leaflets, short posterior leaflet, coaptation gap >10 mm, MVA <4 cm² after clipping — Harrison's Principles, p. 2100; Sabiston Textbook of Surgery, p. 2619

• Emerging option for patients unsuitable for TEER due to complex anatomy
• Valve-in-valve (ViV) for failed bioprostheses — FDA-approved 2017 (Class IIa for non-surgical candidates)
• Dedicated TMVR systems (Intrepid, Tendyne) in early feasibility trials
• Challenges: LVOT obstruction, transseptal delivery, sizing

3. Secondary (Functional) Mitral Regurgitation

Medical Therapy (First-Line)

• GDMT for HF is the cornerstone: ACE inhibitors/ARBs, ARNi (sacubitril/valsartan — reduces EROA), beta-blockers, MRAs
• Cardiac resynchronization therapy (CRT) — reduces secondary MR in 30–40% of patients with dyssynchrony
• GDMT reduces MR in up to 40% of patients and is prioritised before any intervention — Braunwald's Heart Disease, p. 786

Surgical Therapy — Secondary MR

• MV repair (annuloplasty ring) or replacement at the time of CABG is recommended in severe ischemic MR undergoing revascularisation
• For moderate ischemic MR + CABG: adding MV repair did not improve LV remodelling or survival vs CABG alone (CTSN trial) — repair may be omitted
• For isolated secondary MR: no Class I or IIa indication for surgery — reflects limited benefit over medical therapy

Transcatheter TEER — Secondary MR

• TEER group: significantly fewer HF hospitalisations and lower all-cause mortality at 5-year follow-up
• First randomised trial showing survival benefit in HF + secondary MR
• FDA broadened TEER indication to symptomatic functional MR irrespective of surgical risk (2019)

• Severe secondary MR symptomatic despite optimal GDMT with LVEF 20–50%

The European MITRA-FR trial did not show benefit — patient selection differences (proportionate vs. disproportionate MR) explain the discordance; those with "disproportionate" MR (EROA large relative to LV size) benefit most.

4. Overview of Transcatheter Mitral Interventions

5. Key Decision Framework

Mitral Valve Disease
├── Mitral STENOSIS
│   ├── Favourable anatomy + no contraindication → PBMC/BMV
│   └── Unfavourable anatomy / contraindication → Surgical repair or MVR
│
└── Mitral REGURGITATION
    ├── PRIMARY (organic)
    │   ├── Surgical candidate → MV REPAIR (preferred) or MVR
    │   └── High/prohibitive surgical risk → TEER (MitraClip/PASCAL)
    │                                         or TMVR (ViV or dedicated)
    └── SECONDARY (functional)
        ├── All patients → Optimise GDMT + CRT if indicated
        ├── LVEF 20–50%, symptoms persist → TEER (Class IIa)
        └── Severe MR + CABG needed → MV repair/replacement at CABG

• PMID [39960383] — Systematic review on rheumatic MV surgery (repair vs. replacement, 2025)
• PMID [36775783] — Anatomic stage-based repair for secondary MV disease (meta-analysis, 2024)