What are the management options for abdominal aortic aneurysm (AAA)?

Management of Abdominal Aortic Aneurysm

Management of AAA is determined primarily by aneurysm diameter, with elective repair recommended at ≥55 mm in men or ≥50 mm in women, while smaller aneurysms undergo surveillance imaging at intervals based on size. 1

Surveillance Strategy for Small AAAs

For asymptomatic AAAs below surgical thresholds, surveillance intervals are determined by maximum diameter 1:

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

Small AAAs (<55 mm) should not undergo immediate surgery, as randomized trials demonstrate no long-term survival benefit from early repair and show early operative mortality disadvantages. 2 The UKSAT and ADAM trials found no significant differences in long-term survival between immediate surgery and surveillance (adjusted HR 0.88,95% CI 0.75-1.02 at 10 years; HR 1.21,95% CI 0.95-1.54 at 4.9 years). 2

Indications for Surgical Intervention

Proceed with elective repair when AAA reaches ≥55 mm in men or ≥50 mm in women, regardless of thrombus configuration or other anatomic features. 1

Additional triggers for intervention include 1:

• Rapid growth ≥10 mm per year or ≥5 mm in 6 months
• Saccular morphology ≥45 mm (higher rupture risk)
• Any symptomatic AAA regardless of diameter (abdominal/back pain, pulsatile mass)

All symptomatic AAAs warrant urgent repair immediately after stabilization, as symptoms indicate imminent rupture risk. 3

Choice of Repair Technique

Endovascular aneurysm repair (EVAR) should be considered as preferred therapy for patients with suitable anatomy and life expectancy >2 years, based on shared decision-making. 1 EVAR reduces perioperative mortality to <1% compared to open repair. 1

For ruptured AAA with suitable anatomy, perform endovascular repair over open repair to reduce perioperative morbidity and mortality. 1, 3

Open repair remains appropriate for 4:

• Patients who cannot comply with mandatory long-term post-EVAR surveillance
• Patients with anatomy unsuitable for EVAR
• Young patients with long life expectancy where durability is paramount

Both techniques involve 4:

• Open repair: Surgical removal of aneurysmal segment with synthetic graft replacement
• EVAR: Endovascular placement of stent graft to exclude aneurysm from circulation

Pre-Intervention Imaging

Obtain contrast-enhanced CT as the mandatory pre-operative imaging modality to assess the complete aorto-iliac system, measure true aneurysm diameter, evaluate thrombus burden, and determine EVAR feasibility. 1

Perform duplex ultrasound of the femoro-popliteal segment, as femoro-popliteal aneurysms commonly coexist with AAA. 1

Medical Management

Implement optimal cardiovascular risk management for all AAA patients to reduce major adverse cardiovascular events. 1 This includes:

• Smoking cessation (strongest modifiable risk factor) 5, 6
• Blood pressure control, particularly with ACE inhibitors (observational data suggest benefit for rupture prevention) 6
• Avoid fluoroquinolones unless compelling indication with no alternative 1

No pharmacologic therapy has been proven in randomized trials to slow AAA growth. 6 Thirteen placebo-controlled trials testing antibiotics, blood pressure medications, mast cell stabilizers, antiplatelet drugs, and fenofibrate have failed to show convincing efficacy. 6 Metformin shows promise in observational studies and is under investigation. 6

Post-Intervention Surveillance

After EVAR, perform 30-day imaging with contrast-enhanced CT plus duplex ultrasound to assess intervention success. 1

Follow-up schedule 1:

• 1 month post-operatively
• 12 months post-operatively
• Yearly until fifth post-operative year
• Monitor for endoleaks, graft position, and aneurysm sac changes

Re-intervene immediately for Type I or Type III endoleaks to achieve seal and prevent rupture. 1, 3 These endoleaks allow continued pressurization of the aneurysm sac. 3

Management of Ruptured AAA

For hemodynamically unstable patients with suspected rupture, implement permissive hypotension strategy (systolic BP <120 mmHg) to decrease bleeding rate until definitive treatment. 3

Initiate anti-impulse therapy with intravenous beta blockers as first-line agents, targeting heart rate 60-80 bpm and systolic BP <120 mmHg. 3

For hemodynamically stable patients, obtain CT imaging to evaluate suitability for endovascular repair before proceeding. 3

The clinical triad of abdominal/back pain, pulsatile abdominal mass, and hypotension indicates rupture—failure to recognize this leads to delayed treatment and increased mortality. 3 Overall mortality from ruptured AAA remains 75-90% despite treatment. 4, 5

Screening Recommendations

Men ages 65-75 who smoke or have ever smoked should receive one-time AAA screening with ultrasound. 4 This reduces risk of dying from ruptured AAA by approximately 50%. 4

Screening can be considered for men ages 65-75 who have never smoked, though benefit is limited. 4

Women who have never smoked should not receive routine AAA screening. 4 Evidence for screening women ages 65-75 who smoke remains insufficient. 4