What is the management approach for an infrarenal (below the renal arteries) fusiform abdominal aortic aneurysm (AAA) with an anterior mural thrombus?

Management of Infrarenal Fusiform AAA with Anterior Mural Thrombus

Management is determined primarily by aneurysm diameter, not by the presence of mural thrombus, which is a common finding that does not independently alter treatment thresholds. 1

Size-Based Management Algorithm

For AAAs ≥5.5 cm

• Repair is indicated to eliminate rupture risk, regardless of thrombus presence. 1
• Both open surgical repair (OSR) and endovascular aneurysm repair (EVAR) are appropriate options for good surgical candidates. 1
• EVAR is preferred for most patients due to lower 30-day mortality (1.16% vs 3.27% for open repair). 2
• Open repair should be chosen if the patient cannot comply with mandatory lifelong post-EVAR surveillance imaging. 1

For AAAs 5.0-5.4 cm

• Repair can be beneficial and should be strongly considered. 1
• This is particularly true for women, where intervention is recommended at ≥5.0 cm (compared to ≥5.5 cm for men). 3, 2
• Obtain CT angiography to assess anatomic suitability for EVAR and plan the repair approach. 1, 4

For AAAs 4.0-5.4 cm

• Monitor with ultrasound or CT every 6-12 months to detect expansion. 1
• Intervention is NOT recommended for asymptomatic AAAs <5.0 cm in men or <4.5 cm in women. 1
• CT angiography may be helpful to describe aneurysm morphology, as saccular morphology increases rupture risk even below size thresholds. 1

For AAAs <4.0 cm

• Monitor by ultrasound every 2-3 years. 1, 5

Critical Indications for Immediate Repair (Regardless of Size)

If the patient develops abdominal/back pain, pulsatile mass, and hypotension, immediate surgical evaluation is mandatory. 1

Any symptomatic AAA requires repair regardless of diameter. 1

Rapid expansion (≥0.5 cm in 6 months or ≥1.0 cm/year) warrants repair within 2-4 weeks. 4, 3

Role of Mural Thrombus

The presence of anterior mural thrombus is a common finding in AAAs and should be documented during surveillance imaging. 1 While mural thrombus has been associated with expansion rates, it does not independently change size-based repair thresholds. 1, 6 The key is to measure the external anteroposterior diameter of the aneurysm, not the residual lumen. 1

Common pitfall: Do not measure only the patent lumen—the full external diameter including thrombus determines rupture risk and repair indication. 1

Pre-Intervention Imaging

Once repair is indicated, obtain multidetector CT angiography (CTA) with 3D reconstruction to:

• Define optimal surgical vs endovascular approach 1, 4
• Assess neck anatomy, iliac access, and EVAR suitability 1, 7
• Note that smaller aneurysms are MORE likely to be anatomically suitable for EVAR (84.7% if <5.7 cm vs 63.2% if larger). 7

Medical Management During Surveillance

• Smoking cessation is mandatory—offer behavior modification, nicotine replacement, or bupropion. 1, 5
• Beta-blockers may be considered to reduce expansion rate. 1, 5
• Aggressive blood pressure control reduces wall stress. 4
• Perioperative beta-blockade is indicated for patients with coronary disease undergoing repair. 1

Post-EVAR Surveillance Requirements

Lifelong surveillance imaging is mandatory after EVAR to monitor for endoleaks, sac stability, and stent migration. 1, 4 The recommended schedule is CT at 1 month, 12 months, then annually if stable. 4 Non-compliance carries a 10% rupture rate versus 0% in compliant patients. 4 The long-term reintervention rate is approximately 18%. 2

Family Screening

Men ≥60 years who are siblings or offspring of AAA patients should undergo ultrasound screening. 1, 5, 4