What is the recommended management of an infrarenal abdominal aortic aneurysm in adults?

Management of Infrarenal Abdominal Aortic Aneurysm

Elective repair is recommended when the infrarenal AAA reaches ≥55 mm in men or ≥50 mm in women, with endovascular repair (EVAR) preferred over open repair in patients with suitable anatomy and life expectancy >2 years. 1

Size-Based Intervention Thresholds

Mandatory repair indications:

• AAA diameter ≥55 mm in men 1
• AAA diameter ≥50 mm in women 1
• Any symptomatic AAA regardless of size (abdominal/back pain, pulsatile mass, hypotension requires immediate surgical evaluation) 1
• Saccular aneurysms ≥45 mm may warrant repair 1

Conditional repair (Class IIa):

• AAA diameter 50-54 mm can be beneficial, particularly in good surgical candidates 1

Surveillance without intervention:

• AAA <50 mm in men or <45 mm in women should NOT undergo elective repair 1
• AAA 40-54 mm: monitor with ultrasound or CT every 6-12 months 1, 2
• AAA <40 mm: monitor with ultrasound every 2-3 years 1, 2

Rapid expansion criteria:

• Growth ≥5 mm in 6 months or ≥10 mm per year may warrant repair regardless of absolute diameter 1, 3

Pre-Operative Evaluation

Mandatory imaging:

• CT angiography is the optimal pre-operative imaging modality to assess anatomy and EVAR feasibility 1, 2
• Duplex ultrasound of femoro-popliteal segment should be performed to detect concomitant aneurysms 1
• Evaluate entire aorta (ascending, arch, descending) to determine optimal strategy 1

Cardiac evaluation:

• Routine coronary angiography and systematic revascularization is NOT recommended in patients with chronic coronary syndromes 1
• Pre-operative cardiac work-up depends on procedure risk and patient-specific cardiovascular risk factors 1

Treatment Selection: EVAR vs Open Repair

EVAR is preferred when:

• Patient has suitable anatomy for endovascular repair 1
• Life expectancy >2 years 1
• Patient can comply with mandatory lifelong surveillance 1, 2
• EVAR reduces peri-operative mortality to <1% compared to open repair 1

Open repair is preferred when:

• Patient cannot comply with lifelong post-EVAR surveillance requirements 1, 2
• Hostile neck anatomy makes EVAR unsuitable 3
• Patient has limited life expectancy <2 years (neither repair recommended) 1

For ruptured AAA:

• Endovascular repair is recommended over open repair to reduce peri-operative morbidity and mortality 1
• Open repair for ruptured AAA has ~48% complication rate 1

Post-EVAR Surveillance Protocol

Critical surveillance requirements:

• Lifelong surveillance imaging is mandatory after EVAR to monitor for endoleaks, sac stability, and stent migration 1, 2
• CT or duplex ultrasound at 6-12 months post-procedure 1
• Annual surveillance for first 5 years 1
• Non-compliance with surveillance is associated with 10% rupture rate vs 0% in compliant patients 2, 3

Endoleak management:

• Type I and Type III endoleaks require immediate correction with new endovascular procedure 1
• Type II endoleaks occur in ~25% of patients but may spontaneously seal; monitor with surveillance 1
• Growing aneurysm sac ≥10 mm warrants consideration of embolization 1

Medical Management During Surveillance

Risk factor modification:

• Smoking cessation is mandatory and should include behavior modification, nicotine replacement, or bupropion 1, 2
• Aggressive blood pressure control to reduce wall stress and expansion risk 2, 3
• Beta-blockers may be considered to reduce aneurysm expansion rate 1, 2

Peri-operative management:

• Beta-blockers are indicated peri-operatively in patients with coronary artery disease undergoing open repair to reduce cardiac events 1

Special Populations and Screening

Family screening:

• Men ≥60 years who are siblings or offspring of AAA patients should undergo physical examination and ultrasound screening 1, 3

Contraindications to elective repair:

• Patients with limited life expectancy <2 years should NOT undergo elective AAA repair 1

Critical Pitfalls to Avoid

• Never discontinue surveillance after EVAR prematurely—late rupture risk remains >5% through 8 years 2
• Do not rely solely on ultrasound for entire EVAR follow-up—may miss stent migration, fracture, or non-contiguous aneurysms 2
• Do not delay repair in symptomatic patients regardless of diameter—these require urgent intervention within 24-48 hours 3
• Ultrasound-guided percutaneous access for EVAR reduces access-related complications and operation time 1
• Consider prophylactic mesh in obese patients undergoing open repair due to high incisional hernia risk 1