What are the guidelines for mitral valve replacement surgery in patients with left atrial thrombus?

Guidelines for Mitral Valve Replacement Surgery with Left Atrial Thrombus

For patients with mitral valve disease and left atrial thrombus requiring valve replacement, anticoagulation with vitamin K antagonist therapy (target INR 2.5, range 2.0-3.0) is mandatory before surgery, and the procedure should be postponed until thrombus resolution is documented by transesophageal echocardiography. 1

Preoperative Management

Detection and Assessment

• Transesophageal echocardiography (TEE) is essential for:
  • Confirming presence and location of thrombus
  • Assessing thrombus size and mobility
  • Evaluating left atrial appendage function
  • Detecting spontaneous echo contrast 2

Anticoagulation Protocol

• For patients with rheumatic mitral valve disease and left atrial thrombus:

  • Initiate vitamin K antagonist (VKA) therapy with target INR of 2.5 (range 2.0-3.0) 1
  • Continue anticoagulation for at least 2-6 months 1
  • Repeat TEE to document thrombus resolution before proceeding with surgery 1

• For patients being considered for percutaneous mitral balloon valvotomy (PMBV):

  • Higher intensity anticoagulation with target INR of 3.0 (range 2.5-3.5) 1
  • Postpone procedure until thrombus resolution is documented 1

Predictors of Thrombus Resolution

• NYHA functional class II or better
• Left atrial appendage thrombus size < 1.6 cm²
• Less dense spontaneous echocardiographic contrast
• INR ≥ 2.5 1

Surgical Considerations

Timing of Surgery

• If thrombus resolves with anticoagulation:

  • Proceed with mitral valve replacement surgery
  • Consider concomitant left atrial appendage excision to reduce future thromboembolic risk 1, 3

• If thrombus persists despite adequate anticoagulation:

  • Surgery is preferred over percutaneous approaches 1
  • Surgical removal of thrombus should be performed concurrently with valve replacement 2

Intraoperative Management

• Intraoperative TEE is crucial to:

  • Monitor for clot dislodgement
  • Assess hemodynamic parameters
  • Guide fluid management
  • Detect new thrombus formation 2

• Surgical techniques:

  • Complete removal of left atrial thrombus is mandatory
  • Consider left atrial appendage excision or closure 3
  • Careful handling of the heart to prevent thrombus dislodgement

Postoperative Management

Anticoagulation

• For mechanical valve replacement:

  • Lifelong VKA therapy (target INR 2.5, range 2.0-3.0)
  • Consider addition of low-dose aspirin (50-100 mg/d) if low bleeding risk 1

• For bioprosthetic valve replacement:

  • VKA therapy for at least 3 months
  • Continued indefinite anticoagulation if:
    • History of atrial fibrillation
    • Depressed ventricular function
    • Low cardiac output
    • Preoperative history of embolism or intraoperative finding of left atrial thrombus 4

Follow-up

• Regular echocardiographic assessment of prosthetic valve function
• Close monitoring of anticoagulation therapy, preferably in specialized anticoagulation clinics 4
• Vigilance for symptoms of heart failure or valve dysfunction, as clinical deterioration can be rapid 5

Important Caveats

1. Never discontinue anticoagulation in patients with history of left atrial thrombus, even after successful left atrial appendage excision 6

2. Surgical excision of left atrial appendage alone is insufficient to prevent thromboembolism without appropriate anticoagulation 3

3. Thrombus and pannus often coexist in cases of prosthetic valve obstruction, making surgical assessment crucial 5

4. Patients with large left atrial thrombi who are poor surgical candidates may benefit from extended anticoagulation therapy, as complete resolution of large thrombi has been documented with prolonged warfarin therapy 7

5. Emergent surgery carries higher risk in patients with left atrial thrombus; therefore, anticoagulation with thrombus resolution prior to elective surgery is the preferred approach 2