When should a bicuspid aortic valve be replaced?

When to Replace a Bicuspid Aortic Valve

Replace a bicuspid aortic valve when severe stenosis or regurgitation develops with symptoms, left ventricular dysfunction, or when undergoing other cardiac surgery—and simultaneously replace the ascending aorta if its diameter exceeds 4.5 cm. 1, 2

Valve Replacement Indications

For Severe Aortic Stenosis or Regurgitation

Operate when any of the following criteria are met:

• Symptomatic severe disease (exertional dyspnea, angina, dizziness, or syncope) 3
• Left ventricular ejection fraction decline or significant LV diameter changes approaching intervention thresholds 3
• Undergoing concurrent cardiac surgery (CABG or mitral valve surgery), even with moderate aortic valve dysfunction 3

The guidelines emphasize careful symptom exploration, as patients often deny symptoms by unconsciously reducing their activity levels 3. Serial echocardiography every 6 months is warranted when LV parameters approach intervention thresholds or show significant changes 3.

Ascending Aorta Management During Valve Replacement

When performing aortic valve replacement for severe stenosis or regurgitation, simultaneously replace the ascending aorta if diameter exceeds 4.5 cm. 3, 1, 2

This lower threshold (4.5 cm versus the 5.5 cm used for isolated aortic aneurysms) reflects the opportunity to address both pathologies in a single operation, avoiding future reoperation risk 1. A case report illustrates this principle: a patient underwent valve replacement with aortoplasty for a 4.3 cm ascending aorta, only to suffer ascending aorta rupture requiring reoperation 6 years later 4.

Isolated Ascending Aorta Surgery (Without Valve Dysfunction)

For isolated ascending aortic aneurysms without significant valve dysfunction:

• Operate at 5.5 cm in patients without additional risk factors 1, 2
• Lower threshold to 5.0 cm when risk factors are present:
  • Family history of aortic dissection 1, 2
  • Rapid aortic growth ≥0.5 cm per year 1, 2, 5
  • Aortic coarctation 1
  • Resistant hypertension 1, 5
  • Age <50 years 1
  • Desire for pregnancy 1

Surveillance Protocol

For bicuspid aortic valve patients, implement the following monitoring strategy:

Valve Assessment

• Mild-to-moderate dysfunction: Annual clinical visits with echocardiography every 2 years 3
• Severe dysfunction with normal LV function: Initial 6-month follow-up, then 6-month intervals if parameters are changing, or yearly if stable 3

Aortic Surveillance

• Ascending aorta >4.0 cm: Annual imaging with echocardiography, MRI, or CT 3, 1, 2, 5
• Ascending aorta 4.0-4.5 cm: Serial imaging at intervals determined by progression rate 2
• When diameter exceeds 4.5 cm or increases >3 mm per year: Annual measurements, with CT or MRI confirmation 1

Use cardiac MRI or CT when echocardiography cannot adequately visualize the ascending aorta beyond 4.0 cm from the valve 3, 1, 2. MRI is preferred over CT in younger patients requiring lifelong surveillance to avoid cumulative radiation exposure 2, 6.

Critical Pitfalls to Avoid

• Do not rely solely on echocardiography if the ascending aorta cannot be adequately visualized—obtain MRI or CT 2
• Do not compare measurements from different imaging modalities without accounting for systematic differences (MRI/CT measurements are typically 1-2 mm larger than echocardiography) 5
• Do not miss the cusp fusion pattern—patients with noncoronary cusp involvement have higher risk of extensive aortic dilation (68% versus 40%) extending to the transverse arch 2
• Do not overlook family screening—20-30% of first-degree relatives have bicuspid valve disease or associated aortopathy 2
• Do not extend surveillance intervals beyond 12 months for aortic diameters >4.0 cm, as rapid growth can occur unpredictably 5

Medical Management While Monitoring

No proven medical therapies exist to reduce progression of bicuspid aortic valve-associated aortopathy. 2 However:

• Control hypertension with any effective antihypertensive agent 2
• Beta-blockers and ARBs have theoretical advantages but lack proven benefit in clinical studies for slowing aortic dilation 3, 2
• Mandate immediate smoking cessation, as smoking doubles the rate of aneurysm expansion 5