Cardiology

Mitral Stenosis Intervention

Updated December 19, 2021

Abbreviations

  • TTE: trans-thoracic echocardiography
  • TEE: trans-esophageal echocardiography
  • PMBC: percutaneous mitral balloon commissurotomy
  • PASP: pulmonary artery systolic pressure
  • TAVI: transcatheter aortic valve implantation

Introduction

  • Options of fixing stenotic valves include percutaneous vs. open and valvuloplasty vs. replacement
  • Decision should involve a Valve Team and is individualized to every patient
  • Patient profile and technical factors influence decision
  • Choosing what type of intervention will be the focus of this article. Diagnosing stenotic lesions and medical therapy are discussed here.

Rheumatic Mitral Stenosis

Diagnosis

  • TTE is indicated to establish diagnosis and TEE if percutaneous mitral balloon commissurotomy (PMBC) is being considered
  • If discrepancy between clinical and echocardiographic parameters, exercise testing or cardiac catheterization can be done

Criteria

  • Severe mitral stenosis is diagnosed by:
    • Mitral valve area <1.5 cm2
      • Calculated by planimetry or diastolic pressure half time (>150 ms)
    • Mean gradient usually above 5-10 mmHg (at normal heart rate)
      • Varies by heart rate thus not included in definition
    • Ancillary findings:
      • Severe LA enlargement
      • Elevated pulmonary artery systolic pressure (>50 mmHg)

Interventions

  1. Percutaneous mitral balloon commissurotomy (PMBC)
    • Indicated in patients with:
      • Pliable valve, no clot, <2+ MR with symptoms OR
      • No symptoms and high PASP (>50 mmHg) OR
      • New AF
  2. Mitral Valve Surgery
    • Surgical commissurotomy preferred vs mitral valve replacement 
    • Indicated in patients with severe symptoms (NYHA III or IV) who are surgical candidates
  3. Trans-catheter valve implantation of TAVI bioprosthesis
    • If not a PMBC or surgical candidate
AHA 2020 - Intervention for MS

PMBC

  • TTE for diagnosis of severe MS and TEE to look for thrombus and severity of MR
  • Goal is to use a balloon to split the commissures (instead of splitting the valve)
  • Good candidates have pliable valves:
    • Crisp opening snap and loud S1
    • Wilkins Score <8
    • No calcium in commissures
  • Contraindications
    • Moderate or greater MR
    • LA thrombus

Mitral Valvuloplasty (Wilkins/MGH) Score

  • Wilkins score 8 or less predicts a favorable result but a score greater than 8 does not preclude PMBC
  • Calculator
Schematic Representation of the Wilkin Score
Willkins Score

Non-Rheumatic Calcific Mitral Stenosis

  • Though rheumatic mitral stenosis is the most common cause of mitral stenosis, calcific mitral stenosis is becoming more common in elderly populations
  • In contrast to rheumatic, calcification starts at the base and usually spares the leaflet tips
    • No commissural fusion
  • Determination of severity is difficult as planimetry is challenging

Interventions

  • No role for PMBC or surgical commissurotomy
  • Surgery is technically challenging as mitral annular calcification causes difficulty in securing a prosthesis
  •  Guidelines recommend valve intervention in patients with severe symptoms (NYHA III or IV), severe mitral stenosis (mitral valve area < 1.5 cm2) and after discussion of the high operative risk with the patient

Further Reading

  • 2020 AHA: Guideline for the Management of Patients With Valvular Heart Disease (html) (pdf)

Authors

  • Author: Atul Jaidka (MD, FRCPC, Cardiology Fellow)
  • Copy Editor: Megha Shetty (MD Candidate)
  • Last Updated: April 5, 2021
  • Comments or questions please email feedback@cardioguide.ca