Contraindications for Mitral Valve Balloon Valvuloplasty
Percutaneous mitral balloon valvuloplasty is contraindicated in patients with left atrial thrombus, moderate-to-severe mitral regurgitation (grade 3-4), severe or bicommissural calcification, absence of commissural fusion, or unfavorable valve morphology. 1
Absolute Contraindications
- Left atrial thrombus: The most important contraindication due to high risk of systemic embolization during the procedure 1, 2
- Moderate to severe mitral regurgitation (grade 3-4): Can worsen significantly after balloon dilation 1, 2
- Severe or bicommissural calcification: Associated with poor procedural outcomes and increased complication rates 1, 2
- Absence of commissural fusion: Makes the procedure ineffective since the mechanism relies on splitting fused commissures 1
- Mitral valve area >1.5 cm²: Not considered clinically significant stenosis requiring intervention 1, 2
Unfavorable Valve Morphology Characteristics
Valve morphology is a critical determinant of procedural success and is assessed using echocardiographic scoring systems:
- Wilkins score >8: Indicates unfavorable valve characteristics 1, 2
- Cormier score 3: Any degree of valve calcification as assessed by fluoroscopy 1, 2
- Severe subvalvular apparatus involvement: Thickened, fused chordae tendineae 1, 2
Relative Contraindications and High-Risk Features
- Severe concomitant valvular disease: Severe aortic valve disease or severe combined tricuspid stenosis and regurgitation 1
- Advanced age: Associated with more complex valve pathology and calcification 1
- Previous commissurotomy: May indicate more advanced disease 1
- NYHA class IV heart failure: Associated with higher procedural risk 1
- Permanent atrial fibrillation: Higher risk of left atrial thrombus 1
- Severe pulmonary hypertension: May indicate more advanced disease 1
Special Considerations for Left Atrial Thrombus
When left atrial thrombus is located only in the left atrial appendage:
- PMC may still be considered in patients with contraindications to surgery
- Oral anticoagulation should be administered for 2-6 months
- Repeat transesophageal echocardiography must confirm thrombus resolution before proceeding 2, 1
- If thrombus persists, surgical intervention is indicated 2
Pre-Procedure Evaluation
All patients being considered for mitral balloon valvuloplasty should undergo:
- Comprehensive 2D and Doppler echocardiographic examination to evaluate:
- Appearance and mobility of the mitral valve apparatus
- Commissural fusion pattern
- Transmitral gradient and mitral valve area
- Pulmonary artery pressure 2
- Transesophageal echocardiography to:
- Rule out left atrial thrombus (particularly in the left atrial appendage)
- Assess severity of mitral regurgitation 2
- Left ventriculogram if there is suspicion of significant mitral regurgitation 2
Clinical Implications
The success of percutaneous mitral balloon valvuloplasty is highly dependent on patient selection. The procedure works best in patients with:
- Pliable, non-calcified valves
- Mild subvalvular fusion
- No calcium in the commissures 2
In these optimal candidates, success rates exceed 90% with complication rates below 3% and sustained improvement in 80-90% of patients over 3-7 years 2.
Patients with unfavorable valve morphology have higher acute complication rates and lower event-free survival rates (approximately 50% at 5 years compared to 80-90% in those with favorable morphology) 2.
The procedure should only be performed by skilled operators at institutions with extensive experience in the technique 2.