FRCA Notes

Transcatheter Mitral Valve Repair

Transcatheter MVR seems an unlikely CRQ question, but is included on the basis of the recent BJA Education article on the topic.

Resources

  • Mitral regurgitation is a common valvular pathology, causing:
    • Limited functional ability due to dyspnoea and fatigue
    • Higher-than-expected healthcare use due to more frequent admissions with heart failure (50% increase) and excess mortality (6.3%/yr)
  • Although surgical valve replacement or repair has been the historical treatment for such patients, a growing number are undergoing transcatheter valve repair
  • Severe, primary MR with high operative risk and favourable valvular anatomy
  • Refractory secondary MR despite optimised medical therapy and treatment of concomitant coronary artery disease

Approaches & evidence base

Repair strategy Delivery to mitral valve
Edge-to-edge Femoral vein
Trans-septal
Annuloplasty Femoral or jugular vein
Trans-septal
Chordae repair Transapical
  • The dominant approach is the edge-to-edge repair

  • Transcatheter repair was associated with fewer adverse events but a smaller reduction in MR vs. surgical repair (EVEREST II trial)
    • As effective as surgical repair in older patients with secondary MR in sub-group analysis
  • No difference in hospitalisation or mortality at 1 yr vs. surgical repair (Mitra-FR trial)
  • 42% decrease in hospitalisation and 17% decrease in mortality at 2yrs vs. surgical repair (COAPT trial)
  • Ongoing REPAIR MR trial looking at transcatheter vs. surgical repair in moderate risk patients

Relative contraindications

Valve-related Atria-related
Area <3cm2 Small LA
Leaflet length <6mm <35mm above MV on atrial septum
Mean pressure gradient >5mmHg
Calcification at grasping area
Thrombus/mass on valve or annulus
Regurgitation at commissure
Regurgitation due to leaflet cleft


Vascular access

  • Trans-femoral venous approach
  • Wire into RA, confirmed by fluoroscopy ± TOE
  • Heparin IV to ACT 250-300s

Trans-septal puncture

  • Puncture through the atrial septum approximately 4-4.5cm above the mitral valve annulus
  • Wire inserted into the LA and puncture site balloon dilated
  • Valve delivery system advanced under continuous TOE imaging to ensure proper placement

Valve deployment and assessment

  • Clip passed through the delivery system and steered towards appropriate position using TOE
  • Clip grasps MV leaflets
  • Once the clip is attached, the MV is carefully assessed for:
    • Adequate leaflet insertion
    • Residual MR
    • New mitral stenosis; target mean diastolic gradient <6mmHg
  • Further clips may be deployed in order to reduce MR severity to mild or less
  • Need to ensure haemodynamics reflect the 'awake state' during mitral valve assessment

Post-deployment

  • Debate as to whether iatrogenic ASD closure is necessary; may be appropriate to close those with high degree of shunt, be it L-R or R-L
  • Wires withdrawn
  • Heparin reversed with protamine
  • Vascular closure device applied to femoral venous access site
  • Complete TOE examination to assess procedure and exclude complications

Perioperative management of the patient undergoing transcatheter MVR


MDT 'Heart' Team

  • All patients reviewed and assessed for suitability by an MDT comprising of:
    • Interventional cardiologist
    • Cardiothoracic surgeon
    • Cardiac anaesthetist
    • ± Radiologist

Assessment

  • Patients presenting for transcatheter repair are often older, frailer and with other comorbidities such as:
    • Heart failure
    • Pulmonary HTN; not associated with poor post-procedural short-term outcomes
    • Tricuspid regurgitation; not associated with poor post-procedural short-term outcomes
    • Existing PPMs or ICDs

  • Those with low LVEF (<40%) are at risk of afterload mismatch post-procedure
    • The repaired MV greatly increases LV afterload
    • This can lead to a decrease in LVEF post-procedure
    • The risk is less with transcatheter repair vs. surgical repair as the reductions in MR are less

Drug management

  • Patients are often on multiple cardiovascular drugs including potential anticoagulation
  • Anti-arrhythmics are generally continued
  • Stop anticoagulants; may need bridging

  • Avoid benzodiazepine premedication as patients at higher risk of delirium

  • Performed in hybrid suite or cardiac catheter lab, so may suffer issues of remote anaesthesia

Monitoring and access

  • AAGBI
  • Arterial line
  • ± CVC if inotropic drugs required, especially in those with poor LVEF

  • TOE required in all patients, mandating GA
  • External defibrillator pads on due to risk of intracardiac wires precipitating malignant arrythmias
  • Direct measurement of LA pressure by the valve delivery system

Anaesthetic technique

Haemodynamic goals

  • As with MR

  • Aim to decrease LV size, which reduces the coaptation gap and makes it easier for the proceduralist to place the new device in the optimal position
  • Achieved by reducing LAEDP & LVEDP (i.e. adequate contractility and reduced volume) through:
    • Low tidal volume strategy (3-6ml/kg) to reduce breath-to-breath movements of the heart
    • Moderate PEEP (5-10cmH2O)
    • Diuretics e.g. furosemide 20-40mg
    • Positive inotropes e.g. dobutamine (2-5μg/kg/min) or milrinone (0.05-0.5μg/kg/min); also help mitigate afterload mismatch
    • Cardioverting AF (chemically or electrically) once LA thrombus excluded by TOE

  • Most are woken at the end of the case
  • Disposition often CCU or HDU-level setting
  • Analgesic requirements typically modest

  • Post-operative:
    • Ongoing monitoring of venous access site
    • CXR to ensure position of clips unchanged
    • TTE to check degree of residual MR, new MS and degree of ASD

  • Long term DAPT but no formal anticoagulation required
  • Discharge typically within 24-48hrs

Risk factors for complications

  • Predictors of prolonged hospital stay: high EuroScore, existing renal dysfunction

  • Predictors of need for re-hospitalisation and 1yr mortality: decreased LVEF, NYHA III or IV heart failure symptoms

  • Complications are more common in those undergoing emergency repair
  • Those undergoing emergency repair e.g. for cardiogenic shock have higher rates of:
    • AF
    • AKI
    • Pericardial collections
    • In-hospital mortality
    • 30-day mortality (as high as 26%)

Complications

  • Major bleeding (3%) e.g. from femoral access site
  • Delayed pericardial tamponade
  • Oesophageal or gastric injury from TOE probe (5%)
  • AKI (18%)
  • Post-operative AF (2.4%)
  • Hypoxia from:
    • Pulmonary oedema
    • Right-to-left shunt across the ASD
  • Device dislodgement/embolisation (rare)
  • Thrombo-embolic phenomenon
  • High risk of developing delirium due to patient cohort