What are the differences between balloon-expandable and self-expanding Transcatheter Aortic Valve Replacement (TAVR) valves?

Differences Between Balloon-Expandable and Self-Expanding TAVR Valves

Self-expanding valves provide superior hemodynamic performance compared to balloon-expandable valves, particularly in patients with small aortic annuli, while balloon-expandable valves offer lower rates of paravalvular leak and pacemaker implantation. 1, 2

Design and Structural Characteristics

Balloon-Expandable Valves

• Made of bovine pericardium mounted in a cylindrical, relatively short cobalt-chromium stent 3
• Examples: Sapien family (Edwards Lifesciences)
• Deployed by balloon inflation that expands the valve to its final position
• Shorter frame design with more rigid structure

Self-Expanding Valves

• Made of porcine pericardium mounted in a taller, nitinol stent with an adaptive shape and supra-annular design 3
• Examples: CoreValve/Evolut family (Medtronic)
• Deployed by gradual release from a delivery catheter, allowing the nitinol frame to expand to its predetermined shape
• Taller frame with more flexible structure

Clinical Performance Differences

Hemodynamic Performance

• Self-expanding valves:
  • Lower mean gradients (7.7 mmHg vs 15.7 mmHg at 12 months) 1
  • Larger effective orifice areas (1.99 cm² vs 1.50 cm²) 1
  • Lower rates of prosthesis-patient mismatch (11.2% vs 35.3%) 1
  • Better performance in small aortic annuli 1, 2
  • Lower rates of hemodynamic structural valve dysfunction (3.5% vs 32.8%) 1

Paravalvular Leak

• Balloon-expandable valves:
  • Lower incidence of paravalvular leak ≥ mild (OR: 0.19; 95% CI: 0.14-0.26) 2
  • Better sealing against the annulus 2, 4

Conduction Disturbances

• Balloon-expandable valves:
  • Lower rates of permanent pacemaker implantation (OR: 0.53; 95% CI: 0.33-0.86) 2
  • Reduced risk of conduction abnormalities 2, 4

Clinical Outcomes

• Similar overall clinical outcomes between newer generation devices:
  • Equivalent primary valve-related efficacy endpoints 5
  • Comparable rates of all-cause mortality, stroke, and rehospitalization for heart failure 1, 5
  • Similar device success rates 2

Patient Selection Considerations

Anatomical Factors Favoring Self-Expanding Valves

• Small aortic annulus (≤430 mm²) 1, 2
• Severe calcification of the aortic annulus/LV outflow tract with risk of rupture 3
• Extremely oval-shaped annulus 3
• Transfemoral access with femoral artery diameter between 5.0-5.5 mm 3
• Valve-in-valve procedures for small failed surgical bioprostheses 4, 6

Anatomical Factors Favoring Balloon-Expandable Valves

• Dilated ascending aorta (>43 mm) 3
• Severely angulated aorta (aorto-ventricular angle >70°) 3
• Need for transapical approach 3
• Patients at higher risk for paravalvular leak 2, 4
• Cases where coronary re-access might be needed in the future 4

Technical Considerations

Delivery and Deployment

• Self-expanding valves:

  • Can be recaptured and repositioned prior to full deployment 3
  • Beneficial in patients with low coronary ostia 3
  • Require a minimum vessel diameter of 5 mm for newer models 3

• Balloon-expandable valves:

  • More precise positioning during deployment 3
  • Only option for transapical approach 3
  • Require a minimum vessel diameter of 6 mm 3

Practical Decision-Making Algorithm

1. Assess annular size:

   • If small annulus (≤430 mm²): Consider self-expanding valve for superior hemodynamics 1, 2
   • If normal/large annulus: Either valve type may be appropriate

2. Evaluate anatomical risk factors:

   • If severe calcification, oval annulus, or risk of annular rupture: Consider self-expanding valve 3
   • If dilated or severely angulated aorta: Consider balloon-expandable valve 3

3. Consider conduction system risk:

   • If pre-existing conduction abnormalities or high risk for pacemaker: Consider balloon-expandable valve 2

4. Assess vascular access:

   • If smaller femoral arteries (5.0-5.5 mm): Self-expanding valve may be preferable 3
   • If transapical approach needed: Must use balloon-expandable valve 3

5. Consider valve-in-valve scenarios:

   • For small failed surgical bioprostheses: Self-expanding valves provide better hemodynamics 4, 6

Common Pitfalls and Caveats

• Durability considerations: Long-term durability data beyond 3-4 years is still limited for both valve types 3
• Operator experience: In patients eligible for either prosthesis, institutional experience and operator preference often guide the final decision 3
• Coronary access: Consider future coronary access needs, especially in younger patients 4
• Sizing accuracy: Accurate pre-procedural imaging and sizing is critical for both valve types to minimize complications 3