What are the risks of an undiagnosed bicuspid aorta?

Risks of Undiagnosed Bicuspid Aortic Valve

Undiagnosed bicuspid aortic valve (BAV) poses significant risks including aortic dilation, dissection, valve dysfunction, and potential sudden death, requiring regular imaging surveillance once detected.

Understanding Bicuspid Aortic Valve

Bicuspid aortic valve is the most common congenital cardiac malformation, affecting 1-2% of the population with a strong male predominance 1. Unlike a normal trileaflet valve, a BAV has only two functional leaflets, which creates abnormal hemodynamics and stress on the valve and surrounding structures.

Key Risks of Undiagnosed BAV:

1. Aortic Dilation and Dissection

   • BAV is a marker of connective tissue abnormalities affecting both the valve and aorta 2
   • Patients have increased risk for aortic enlargement and dissection, even with normal valve function 2
   • The risk of aortic dissection is approximately 4% over a lifetime 3
   • Bicuspid valve is associated with aortic dilatation and increased risk of aortic rupture during pregnancy and delivery 2

2. Valve Dysfunction

   • Progressive development of aortic stenosis (AS) or aortic regurgitation (AR) 1
   • Valve deterioration may be accelerated by physical exercise 4
   • Valve dysfunction often becomes clinically significant by middle age

3. Endocarditis Risk

   • Increased susceptibility to infective endocarditis 1
   • May require antibiotic prophylaxis, particularly for those engaged in contact sports 4

4. Associated Cardiovascular Conditions

   • May coexist with other cardiac anomalies including:
     • Coarctation of the aorta
     • Ventricular septal defect
     • Patent ductus arteriosus 1
   • Associated with Turner syndrome 2

Surveillance and Management Implications

When a bicuspid aortic valve is diagnosed, the following monitoring is recommended:

• Regular Imaging: Once the ascending aorta reaches 40 mm, annual imaging with echocardiography or other techniques is indicated 3
• Family Screening: First-degree relatives should be evaluated for BAV and asymptomatic thoracic aortic disease 2, 5
• Surgical Considerations: Elective surgical repair should be considered when:
  • Aortic diameter reaches 50-55 mm 3
  • Earlier intervention may be warranted based on patient age, body size, and additional risk factors 6

Specific High-Risk Features

Patients with these characteristics require closer monitoring:

• Aortic dimensions of 41-45 mm (sports with low risk of bodily contact may be reasonable) 2
• Rapid growth of aortic diameter (≥3 mm/year) 2
• Saccular aneurysm formation 2
• Uncontrolled resistant hypertension 2
• Family history of aortic dissection 2

Pitfalls in Management

1. Silent Progression: BAV aortopathy is a slow, silent process that can lead to sudden catastrophic events if not monitored 7
2. Underestimation of Risk: The absolute risk for aortic events may seem small, but consequences can be fatal 2
3. Inadequate Imaging: Relying solely on cardiac auscultation without imaging can miss both the BAV and associated aortopathy
4. Failure to Screen Family: Given the hereditary nature (9% of patients have family members who also have BAV), failure to screen first-degree relatives can miss opportunities for early intervention 5

BAV should be viewed as a syndrome incorporating both valve disorders and aortic wall abnormalities that requires lifelong surveillance once detected 1. Early detection through appropriate screening of at-risk individuals is essential for preventing life-threatening complications.