What is the management for an anterior mural thrombus with an abdominal aortic aneurysm (AAA)?

Management of Anterior Mural Thrombus with AAA

The presence of mural thrombus in an AAA does not change the fundamental management approach—treatment decisions are based on aneurysm size, growth rate, and symptoms, with intervention indicated when diameter reaches ≥55 mm in men or ≥50 mm in women, regardless of thrombus configuration. 1

Key Clinical Implications of Mural Thrombus

The presence of mural thrombus in AAA has specific clinical significance that must be recognized:

• Mural thrombus is associated with increased aneurysm expansion rates and should be documented during imaging evaluation 2
• Extensive mural thrombus (>90% circumference) in the proximal neck increases risk of type I endoleak and stent graft migration if endovascular repair is planned 2
• While thrombus presence affects technical considerations for EVAR, it is not an absolute contraindication to endovascular repair 2

Imaging Requirements

For any AAA with mural thrombus, obtain comprehensive imaging to guide management:

• Contrast-enhanced CT angiography (CTA) is mandatory for complete assessment of the aorto-iliac system, true aneurysm diameter measurement, and thrombus burden evaluation 1
• CTA provides critical information about aneurysm size, thrombus presence, and dissection flap that determines intervention planning 2
• Multiplanar reformatted images with centerline 3-D software should be used to accurately measure diameter in tortuous aneurysms 2

Surveillance Strategy

Management is dictated by maximum aneurysm diameter, not thrombus characteristics:

• AAA 25-29 mm: Duplex ultrasound every 4 years 1
• AAA 30-39 mm: Duplex ultrasound every 3 years 1
• AAA 40-44 mm (women) or 40-49 mm (men): Annual duplex ultrasound 1
• AAA 45-50 mm (women) or 50-55 mm (men): Duplex ultrasound every 6 months 1

Indications for Intervention

Proceed to repair when any of these criteria are met:

• Diameter ≥55 mm in men or ≥50 mm in women (primary indication) 1
• Rapid growth ≥10 mm per year or ≥5 mm in 6 months, even if below size threshold 1
• Saccular morphology ≥45 mm due to higher rupture risk 1
• Symptomatic aneurysm (back, abdominal, or flank pain) requires urgent surgical attention 3

Choice of Repair Technique

When intervention is indicated:

• EVAR should be considered as preferred therapy for patients with suitable anatomy and life expectancy >2 years, reducing perioperative mortality to <1% 1
• Extensive mural thrombus covering >90% of proximal neck circumference warrants careful evaluation of EVAR feasibility due to increased endoleak and migration risk 2
• Open surgical repair remains appropriate for patients with unsuitable anatomy for EVAR or those with failed prior EVAR 2
• In ruptured AAA with suitable anatomy, endovascular repair is recommended over open repair to reduce perioperative morbidity and mortality 1

Medical Management (All Patients)

Regardless of aneurysm size or intervention status:

• Implement optimal cardiovascular risk management to reduce major adverse cardiovascular events 1
• Smoking cessation is critical as tobacco use increases aneurysm growth and rupture risk 4
• Blood pressure control is essential 4
• Avoid fluoroquinolones unless compelling indication with no alternative 1

Post-Intervention Surveillance

After EVAR or open repair:

• 30-day imaging with CTA plus duplex ultrasound to assess intervention success 1
• Follow-up at 1 month, 12 months, then yearly until fifth postoperative year 1
• Re-intervene for type I or type III endoleaks to achieve seal 1

Critical Pitfall to Avoid

Do not delay intervention based solely on thrombus presence—completely thrombosed AAAs can maintain 74-90% of systemic intraluminal pressure and retain rupture risk 5. The decision to intervene is based on aneurysm diameter and growth rate, not thrombus characteristics.