What are the risk factors for ascending aortic aneurysm?

Risk Factors for Ascending Aortic Aneurysm

The primary risk factors for ascending aortic aneurysm include genetic disorders (especially Marfan syndrome), bicuspid aortic valve, hypertension, family history of aortic dissection, and advanced age. 1

Genetic and Congenital Risk Factors

• Heritable Thoracic Aortic Disease (HTAD):

  • Marfan syndrome - most common genetic risk factor, found in 50% of patients under 40 years with aortic dissection 1
  • Loeys-Dietz syndrome - more aggressive form with faster growth rates (up to 10 mm/year) 1
  • Vascular Ehlers-Danlos syndrome - requires lower intervention thresholds 1
  • Non-syndromic familial thoracic aortic aneurysm and dissection syndrome 1

• Bicuspid Aortic Valve (BAV):

  • Present in 20-30% of patients with aortic root aneurysms 1
  • Significantly increases risk of ascending aortic aneurysm formation 1

• Family History:

  • 13-19% of patients with thoracic aortic aneurysms have first-degree relatives with thoracic aortic aneurysms or dissection 1
  • Family history of sudden death should prompt consideration of undiagnosed aortic dissection 1

Acquired Risk Factors

• Hypertension:

  • Main risk factor present in approximately 80% of cases 1
  • Often uncontrolled in patients who develop aortic dissection 1
  • Increases wall stress according to the law of La Place 1

• Age and Gender:

  • Aortic root aneurysms: typically younger patients (30-50 years), equal gender distribution 1
  • Supra-coronary aortic aneurysms: typically older patients (59-69 years), male predominance (3:1 ratio) 1

• Other Risk Factors:

  • Smoking 1, 2
  • Atherosclerosis - particularly for descending and abdominal aortic aneurysms 1
  • Trauma/deceleration injuries 1
  • Cocaine or stimulant use 1
  • Extreme exertion or emotional distress 1
  • Coarctation of the aorta 1
  • Inflammatory conditions (e.g., Takayasu's arteritis, giant cell arteritis) 1

Risk Factors for Progression and Complications

• Rapid Growth Rate:

  • Growth ≥3 mm/year in ascending aorta (normal growth is ~1 mm/year) 1
  • Growth rate is faster in familial TAAs (up to 2.1 mm/year) 1

• Large Diameter:

  • Risk of dissection or rupture increases rapidly when diameter exceeds 60 mm for ascending aorta 1
  • At diameter >6 cm, yearly rate of rupture or dissection is approximately 6.9% 3

• Phenotypic Features:

  • Presence of aortic regurgitation 1
  • Saccular aneurysm morphology 1
  • Relation to patient's height (aortic height index) 1, 2

Monitoring and Risk Assessment

• Use of indexed measurements improves risk stratification:

  • Aortic Size Index (ASI): aortic diameter/BSA >22 mm/m² 1, 2
  • Aortic Height Index (AHI): preferred over BSA correction to avoid underestimation in overweight patients 1, 2

• Patients with aortic root involvement (as seen in HTAD) are more prone to acute aortic events 1

• When the aorta reaches 57.5 mm, yearly rates of rupture, dissection, and death are 3.6%, 3.7%, and 10.8%, respectively 1

Clinical Implications

For patients with risk factors, regular imaging surveillance is essential. Intervention thresholds vary based on risk factors:

• 50 mm for patients with Marfan syndrome 1
• 45 mm for Marfan syndrome with additional risk factors (family history of dissection, growth rate >3 mm/year) 1
• 50 mm for bicuspid valve patients with risk factors 1
• 55 mm for patients without elastopathy 1

Early identification of high-risk patients allows for appropriate monitoring, medical management (especially blood pressure control), and timely surgical intervention to prevent the potentially fatal complications of aortic dissection and rupture.