What is the management approach for a patient with an aortic aneurysm identified on a Computed Tomography (CT) scan?

Management of Aortic Aneurysm Detected on CT Scan

Patients with abdominal aortic aneurysms (AAA) ≥5.5 cm in men or ≥5.0 cm in women should be referred for surgical or endovascular intervention, while smaller aneurysms require surveillance imaging at intervals based on aneurysm size. 1

Initial Assessment and Diagnosis

• CT angiography (CTA) is the optimal imaging modality for comprehensive evaluation of aortic aneurysms, providing accurate measurements and detailed anatomic information needed for treatment planning 1
• When an aortic aneurysm is identified at any location, assessment of the entire aorta is recommended at baseline and during follow-up to identify potential multiple aneurysms 1
• Aortic diameter should be measured perpendicular to the longitudinal axis of flow using multiplanar reformatted images that have been angle-corrected for aortic curvature 1
• An aneurysm is defined as a focal dilation at least 1.5 times the normal diameter, generally ≥30 mm for AAA and approximately ≥50 mm for thoracic aortic aneurysm (TAA) 1

Management Algorithm Based on Aneurysm Size

Abdominal Aortic Aneurysm (AAA)

1. Small AAA (3.0-3.9 cm):

   • Ultrasound surveillance every 2-3 years 1
   • Medical management with cardiovascular risk reduction 2

2. Moderate AAA (4.0-4.9 cm):

   • Ultrasound surveillance every 12 months 1
   • Consider more frequent imaging (every 6 months) if rapid expansion (>1 cm/year) is detected 1, 3

3. Large AAA (Men: 5.0-5.4 cm, Women: 4.5-4.9 cm):

   • Ultrasound or CT surveillance every 6 months 1
   • Consider CTA for preoperative planning as diameter approaches intervention threshold 1

4. Intervention threshold:

   • Men: ≥5.5 cm diameter 1
   • Women: ≥5.0 cm diameter 1
   • Any symptomatic aneurysm regardless of size 1
   • Rapid expansion >1 cm/year 1, 3

Thoracic Aortic Aneurysm (TAA)

1. Ascending aorta/aortic root:

   • Intervention recommended at ≥5.5 cm in patients without genetic disorders 1
   • Lower threshold (4.0-5.0 cm) for patients with Marfan syndrome, Loeys-Dietz syndrome, or other genetic disorders 1
   • Surveillance with TTE for proximal ascending aorta, CMR or CCT for distal ascending, arch, or descending thoracic aorta 1

2. Descending thoracic aorta:

   • Intervention recommended at ≥5.5 cm 1
   • Annual imaging with CMR or CCT if stable 1
   • More frequent imaging (every 6 months) as diameter approaches intervention threshold 1

Surveillance Imaging Modalities

• Abdominal aortic aneurysm:

  • Duplex ultrasound (DUS) is recommended as the primary surveillance tool for AAA 1
  • CT or CTA should be performed when ultrasound is inadequate or when planning intervention 1
  • MRA may be substituted if CT cannot be performed (e.g., allergy to iodinated contrast) 1

• Thoracic aortic aneurysm:

  • Transthoracic echocardiography (TTE) for aortic root and proximal ascending aorta 1
  • CMR or CCT for distal ascending aorta, aortic arch, descending thoracic aorta, or thoracoabdominal aortic aneurysm 1
  • TTE is not recommended for surveillance of aneurysms in the distal ascending aorta, aortic arch, or descending thoracic aorta 1

Medical Management

• Optimal cardiovascular risk management is recommended for all patients with aortic aneurysms 1, 2
• Aggressive blood pressure control to reduce wall stress on the aneurysm 2, 4
• Smoking cessation is crucial as it's a major risk factor for aneurysm development and expansion 2, 5
• Statin therapy for atherosclerotic disease management 1
• Regular follow-up with vascular specialists to monitor aneurysm size and determine appropriate timing for intervention 1

Important Considerations and Pitfalls

• Ultrasound tends to underestimate AAA size by approximately 4 mm compared to CTA; this should be considered when comparing measurements between modalities 1
• Presence of thrombus within the aneurysm has been associated with more rapid expansion rates and should be noted during surveillance 1, 6
• Saccular morphology of smaller aneurysms has been associated with increased rupture risk below the standard size threshold for intervention 1
• Approximately 5% of AAAs will be juxtarenal or juxta- and suprarenal, which may not be adequately visualized by ultrasound; CTA should be performed before intervention in these cases 1
• Patients with one aneurysm should be evaluated for other aneurysms, as they frequently coexist 1