What are the prerequisites for transcatheter aortic valve replacement (TAVR) in a patient with severe symptomatic aortic stenosis who is deemed high or intermediate surgical risk?

TAVR Prerequisites

TAVR requires a multidisciplinary Heart Team evaluation, severe symptomatic aortic stenosis confirmed by echocardiography, appropriate surgical risk stratification, suitable vascular anatomy, and predicted post-procedure survival exceeding 12 months. 1

Core Clinical Prerequisites

Diagnosis Confirmation

• Severe aortic stenosis must be documented by echocardiography: aortic valve area ≤1.0 cm² (or ≤0.6 cm²/m² indexed), peak velocity ≥4.0 m/s, or mean gradient ≥40 mmHg. 1
• Symptomatic status is mandatory: patients must exhibit valve-related symptoms including exertional dyspnea, heart failure, syncope, or angina (NYHA class II-IV). 1
• Post-TAVR survival must be predicted to exceed 12 months to justify the intervention over medical therapy alone. 1

Surgical Risk Assessment

• Prohibitive surgical risk (≥50% predicted 30-day mortality or irreversible morbidity): TAVR is the only recommended option. This includes patients with porcelain aorta, prior chest radiation, severe hepatic/pulmonary disease, or frailty with multiorgan dysfunction. 1, 2
• High surgical risk (STS score ≥8%): TAVR is a reasonable alternative to surgical AVR and increasingly preferred. 1
• Intermediate surgical risk (STS score 4-8%): either TAVR or surgical AVR is acceptable; the choice requires Heart Team deliberation considering patient anatomy, comorbidities, and preferences. 1, 3

Anatomical and Technical Prerequisites

Imaging Requirements

• Comprehensive multimodality imaging is essential before TAVR: transthoracic echocardiography for hemodynamic assessment, coronary angiography to evaluate coronary disease, and multislice CT for annular sizing, vascular access evaluation, and coronary ostial height measurement. 4
• Aortic annulus dimensions must fall within device specifications: typically 18-25 mm for balloon-expandable valves and 20-27 mm for self-expanding valves, though newer devices accommodate broader ranges. 5
• Vascular access must be adequate: femoral/iliac arteries should accommodate the delivery system (typically ≥5-6 mm diameter for transfemoral approach); alternative access routes (transapical, transaortic, transcarotid) require surgical capability. 1, 4

Anatomical Exclusions

• Bicuspid aortic valves with severe asymmetric calcification or unfavorable anatomy were historically excluded but are now feasible in experienced centers with newer-generation devices. 5, 6
• Severe proximal coronary artery disease not amenable to percutaneous intervention requires revascularization before TAVR. 5
• Severe aortic regurgitation or mitral regurgitation may require concomitant treatment or alternative strategies. 1

Institutional and Team Prerequisites

Heart Team Composition

• A multidisciplinary Heart Team must evaluate every TAVR candidate: the team includes interventional cardiologists with structural heart expertise, cardiac surgeons, imaging specialists (echocardiography/CT), cardiovascular anesthesiologists, and heart failure cardiologists. 1, 2
• The Heart Team determines: individual patient surgical risk, technical feasibility based on anatomy, appropriateness of TAVR versus surgical AVR, and alignment with patient goals and life expectancy. 1, 2

Institutional Requirements

• On-site cardiac surgery capability is mandatory for TAVR programs to manage acute complications including coronary obstruction, annular rupture, or conversion to open surgery. 1, 5
• Established structural heart disease program with adequate case volumes ensures sustainable high-quality outcomes; initial recommendations suggested minimum operator and institutional volumes, though these have evolved with experience. 1
• Hybrid operating room or catheterization laboratory with advanced imaging (fluoroscopy, echocardiography capability) is required for procedural guidance. 1

Clinical Contraindications

Absolute Contraindications

• Existing comorbidities that preclude expected benefit from AS correction make TAVR inappropriate—specifically when non-cardiac conditions dominate prognosis and limit life expectancy to <12 months. 1, 2
• Active endocarditis is an absolute contraindication to TAVR. 1

Relative Contraindications Requiring Careful Assessment

• Left ventricular ejection fraction <20% was an exclusion in early trials but may be considered in contemporary practice with careful patient selection. 1
• Severe renal insufficiency increases procedural risk but is not an absolute contraindication; contrast-minimizing protocols should be employed. 1
• Recent stroke or TIA within 6 months requires careful neurologic assessment given the 5-8% stroke risk with TAVR. 1

Pre-Procedural Optimization

Coronary Revascularization

• Significant coronary artery disease should be addressed before TAVR through percutaneous coronary intervention in most cases; complex multivessel disease may favor combined surgical AVR plus CABG instead. 2

Medical Optimization

• Avoid aggressive diuresis, vasodilators, and positive inotropes before TAVR as these can precipitate hemodynamic collapse in severe AS. 2
• Maintain adequate preload and avoid excessive volume depletion to preserve cardiac output across the stenotic valve. 2

Patient Education and Consent

• Patients must understand the expected benefits and potential complications including stroke (6-8% at 1 year), vascular complications (10-17%), permanent pacemaker requirement (5-20% depending on valve type), and paravalvular regurgitation. 1, 5

Common Pitfalls to Avoid

• Proceeding without Heart Team evaluation violates guideline recommendations and may result in suboptimal patient selection. 1, 2
• Inadequate CT assessment of annular size leads to paravalvular leak or valve embolization; CT is superior to echocardiography for annular sizing. 4
• Ignoring coronary ostial height risks coronary obstruction, particularly in patients with low coronary ostia or bulky calcified leaflets. 4
• Performing TAVR in patients with <12-month life expectancy from non-cardiac disease provides no mortality benefit. 1
• Delaying intervention in symptomatic patients dramatically worsens prognosis; once symptoms develop, 2-year mortality approaches 50% without valve replacement. 2, 7