In a patient with a bicuspid aortic valve and severe aortic stenosis who is high or intermediate surgical risk, is transcatheter aortic valve replacement (TAVR) appropriate, and what imaging, device sizing, and antithrombotic regimen should be used?

TAVR in Bicuspid Aortic Valve: Current Evidence and Approach

TAVR is explicitly not recommended for bicuspid aortic valve (BAV) in current guidelines, regardless of stenosis severity, due to insufficient data to establish a favorable risk-benefit ratio—however, it may be considered in prohibitive or high surgical risk patients (≥50% mortality risk or STS score ≥8%) with predicted survival >12 months after mandatory multidisciplinary Heart Team evaluation. 1

Guideline Position on BAV and TAVR

The consensus position from ACC, AATS, SCAI, and STS is unequivocal: TAVR should not be used for known bicuspid aortic valve because additional scientific data must be collected before integration into routine clinical care. 1 This restriction applies across all surgical risk categories and all bicuspid valve anatomies. 1 Critically, this recommendation stems from insufficient evidence rather than proven harm, leaving a narrow window for exceptional cases. 1

When TAVR May Be Considered Despite Guidelines

For patients meeting ALL of the following criteria, TAVR may be considered after Heart Team discussion: 1

• Prohibitive or high surgical risk (≥50% predicted 30-day mortality or major morbidity, or STS score ≥8%) 1
• Predicted survival >12 months after intervention 1
• Symptomatic severe aortic stenosis (Stage D) 2
• Mandatory multidisciplinary Heart Team evaluation with interventional cardiology, cardiac surgery, and imaging specialists 1

The 2017 ACC/AHA guidelines establish TAVR as reasonable (Class IIa) for intermediate-risk patients with tricuspid valves, but this does not extend to BAV anatomy. 2

Critical Anatomic and Procedural Considerations

BAV Morphology Predicts Outcomes

Recent registry data from 1,034 CT-confirmed BAV patients undergoing TAVR with contemporary devices revealed that specific morphologic features dramatically impact outcomes: 3

• Calcified raphe plus excess leaflet calcification (present in 26% of patients) was associated with 25.7% 2-year mortality versus 5.9% in those without these features 3
• These high-risk morphologic features predicted higher rates of aortic root injury, moderate-to-severe paravalvular regurgitation, and 30-day mortality 3
• Overall 2-year mortality in BAV TAVR was 12.5%, with 30-day mortality of 2.0% 3

Device-Specific Challenges in BAV

BAV anatomy creates unique technical challenges compared to tricuspid valves: 4

• Lower device success rates due to asymmetric morphology 4
• Increased complication rates with severe calcification 4
• Asymmetric stent geometries resulting from irregular BAV anatomy, potentially increasing thrombosis risk and decreasing durability 4
• Lack of long-term randomized trial data specifically in BAV patients 4

Imaging Requirements for BAV TAVR

Comprehensive CT imaging with core laboratory-level analysis is mandatory to assess: 3

• Number and location of raphes
• Calcification grade in raphe(s)
• Leaflet calcium volume (quantitative assessment)
• Annular dimensions and geometry
• Aortic root anatomy and dimensions

Patients with both calcified raphe AND excess leaflet calcification (>median calcium volume) represent the highest-risk subset and require particularly careful consideration. 3

Antithrombotic Management

While specific antithrombotic regimens for BAV TAVR are not addressed in current guidelines, standard TAVR protocols apply. The asymmetric stent geometries common in BAV may theoretically increase thrombosis risk, though optimal anticoagulation strategies remain undefined. 4

Device Sizing Considerations

BAV anatomy requires meticulous sizing due to: 4

• Asymmetric annular dimensions
• Elliptical rather than circular geometry
• Variable calcification distribution
• Risk of both undersizing (paravalvular leak) and oversizing (annular rupture)

Oversizing should be conservative given the increased risk of aortic root injury in calcified BAV anatomy. 3

Common Pitfalls to Avoid

• Do not proceed with TAVR in BAV patients with acceptable surgical risk—surgical AVR remains the standard of care 1
• Do not rely on routine pre-procedural imaging alone—detailed CT analysis of raphe calcification and leaflet calcium volume is essential 3
• Do not assume all BAV anatomies carry equal risk—morphologic features dramatically stratify outcomes 3
• Do not proceed without Heart Team consensus—this is mandatory even in prohibitive-risk cases 1

Alternative Management

For BAV patients who do not meet criteria for TAVR consideration:

• Surgical AVR remains the gold standard for acceptable surgical risk patients 1
• Balloon aortic valvuloplasty may be considered only as a bridge to definitive therapy in prohibitive-risk patients, not as definitive treatment 2, 5
• Medical management alone carries 68% 2-year mortality in symptomatic severe AS and should be reserved only for patients with <12-month life expectancy from non-cardiac causes 5