Mitral Valve Disease

Indications for Transcatheter Mitral Valve Repair

Transcatheter Mitral Valve Repair Strategies

Role of CT in Assessment of MR/MS and Planning for Transcatheter Mitral Repair

Mitral Valve Disease

• Mitral valve apparatus is composed of anterior and posterior leaflet, chordae tendineae, anterolateral and posteromedial papillary muscles and mitral annulus
• Mitral regurgitation (MR) is most common disorder involving mitral valve and can be classified as either primary or secondary
  • Primary MR is intrinsic structural or degenerative abnormality of valve [e.g., mitral valve prolapse (MVP)]
  • Secondary MR is result of disease process of left ventricle that affects mechanics and function of mitral valve apparatus (e.g., ischemic or nonischemic dilated cardiomyopathy)
• Rheumatic fever is most common cause of mitral stenosis (MS)
• Degenerative calcific mitral valve disease is largely seen in elderly population
• MS can result from leaflet thickening, commissural fusion, and chordal shortening and fusion

Indications for Transcatheter Mitral Valve Repair

• Patients deemed high surgical risk following assessment by heart team with one of the following
  • Primary mitral valve regurgitation: Severe symptomatic mitral regurgitation
  • Asymptomatic: Left ventricular systolic ejection fraction (LVEF) < 60%, left ventricular end-systolic diameter (LVESD) > 45 mm, atrial fibrillation (AF), systolic pulmonary pressure > 50 mm Hg
  • Secondary functional MR: Severe MR despite optimal medical therapy and cardiac resynchronization therapy (CRT)
• Indications for percutaneous balloon mitral valvuloplasty (PBMV) as therapy for MS
• Echocardiography is primary imaging modality for establishing the severity of MR and MS
  • Severe MR is characterized by regurgitant volume of 60 mL, regurgitant fraction of 50%, and effective orifice area of > 0.4 cm²

Transcatheter Mitral Valve Repair Strategies

• Percutaneous mitral valve repair for severe MR includes edge-to-edge repair (MitraClip) and annuloplasty rings (e.g., Cardioband), and PBMV for severe MS
• MitraClip (Abbott Vascular, Menlo Park, California): Can be considered for treatment of moderate to severe and severe degenerative and functional MR
  • Device is delivered to mitral valve via femoral vein following transeptal puncture
  • Aligned above mitral valve and centered over origin of regurgitant jet, advanced across valve orifice, followed by grasping and coapting of leaflets
  • EVERST II trial evaluated MitraClip for treatment of degenerative and functional MR, and at 5 years conventional surgery resulted in greater freedom from death, surgery, or moderate/moderate-severe MR compared to MitraClip device
  • In recently completed COAPT trial of patients with only symptomatic secondary functional MR, device resulted in significant reduction in heart failure hospitalization and all cause mortality at 2 years compared to medical therapy
  • General exclusion criteria: LVEF < 25%, LVESD > 70 mm, mitral valve orifice area < 4 cm²
• Cardioband system (Valtech Cardio, OrYehuda Israel): Traditionally, annuloplasty has been combined with mitral valve repair for degenerative MR to improve leaflet coaptation and long-term durability of repair
  • Percutaneous annuloplasty can be performed in isolation using Cardioband device in setting of functional MR resulting from left ventricular systolic dysfunction, mitral annular dilatation, and lateral papillary muscle displacement
  • Surgical-like annuloplasty device that is implanted along posterior mitral annulus
  • Delivered to left arium following femoral vein access and transeptal puncture
  • After implantation, device is contracted to remodel annulus and reduce MR
  • Early evidence for this device in symptomatic patients with secondary functional MR despite optimal medical therapy, has shown feasibility and safety in small sample size (n = 31) of high-risk patients with MR
  • CT may be used to assess the following in planning for Cardioband device implantation
    • Location of transeptal puncture, left circumflex coronary artery anatomy in relation to mitral annulus (to minimize risk of injury)
  • Exclusion criteria: Patients with LVEF < 25% and end-diastolic diameter ≥ 70 mm, primary (organic) lesions of mitral valve and calcification of mitral annulus
• Percutaneous balloon mitral valvuloplasty (PBMV): Inoue balloon (Toray industries, Japan) is delivered to mitral valve via femoral vein following transeptal puncture
  • Balloon catheter is advanced into left ventricle, pulled back with distal portion of balloon inflated; proximal portion and waist are then inflated
  • Main mechanism of PBMV action is commissural fracture, leading to reduction in transmitral pressure gradient, increasing MV area and cardiac output
  • Superior to surgical commissurotomy, with lager resulting valve area and better durability
  • 1st-line therapy in absence of contraindications
  • Inclusion criteria: Severe symptomatic MS (mitral valve area < 1.5 cm²)
  • Asymptomatic patients: Resting systolic pulmonary arterial pressure > 50 mm Hg, new-onset AF, history of embolism
  • Echocardiography is used to determine suitability for PBMV, depending on leaflet mobility, thickening, calcification, and subvalvular thickening (Wilkins score)
  • Contraindications: Mitral valve area >1.5 cm², left atrial thrombus, > mild MR, severe bicommissural calcification, severe CAD requiring bypass

Role of CT in Assessment of MR/MS and Planning for Transcatheter Mitral Repair