What is the management and treatment approach for abdominal aortic aneurysm (AAA)?

Management and Treatment of Abdominal Aortic Aneurysm

Screening Recommendations

Men aged 65-75 years who currently smoke or have ever smoked should receive one-time ultrasound screening for AAA, which reduces mortality from rupture by approximately 50%. 1

• Men aged 65-75 who have never smoked may be offered screening, though the benefit is substantially lower given the reduced prevalence in this population 1
• Women who have never smoked should not undergo routine AAA screening 1
• Current evidence is insufficient to recommend for or against screening in women aged 65-75 who smoke or have ever smoked 1

Surveillance Strategy Based on Aneurysm Size

Surveillance intervals are determined solely by maximum AAA diameter, using duplex ultrasound (DUS) as the primary modality. 1

The 2024 ESC guidelines provide a clear surveillance algorithm:

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

If DUS cannot adequately measure AAA diameter, cardiovascular CT (CCT) or cardiovascular MRI (CMR) is required 1

Important caveat: Women have similar AAA growth rates to men but a four-fold higher rupture risk at equivalent diameters, justifying the lower intervention thresholds 1

Indications for Intervention

Elective repair is indicated when AAA diameter reaches ≥55 mm in men or ≥50 mm in women. 1, 2

Additional triggers for intervention regardless of size threshold:

• Rapid growth ≥10 mm per year or ≥5 mm in 6 months 1, 2
• Saccular morphology ≥45 mm (higher rupture risk) 3
• Any symptomatic AAA regardless of diameter 2

Pre-Operative Imaging

Contrast-enhanced CT is mandatory before any AAA repair to assess the complete aorto-iliac system, measure true aneurysm diameter, evaluate thrombus burden, and determine EVAR feasibility. 3, 2

• DUS of the femoro-popliteal segment should be performed since femoro-popliteal aneurysms commonly coexist with AAA 3, 2
• Multiplanar reformatted images with centerline 3-D software are necessary for accurate diameter measurement in tortuous aneurysms 3

Choice of Repair Technique

Endovascular aneurysm repair (EVAR) should be considered as the preferred therapy for patients with suitable anatomy and life expectancy >2 years, based on shared decision-making. 1, 2

EVAR advantages:

• Reduces perioperative mortality to <1% compared to open repair 3, 2
• For ruptured AAA with suitable anatomy, endovascular repair is preferred over open repair to reduce perioperative morbidity and mortality 1, 2

Open surgical repair remains appropriate for:

• Patients unable to comply with mandatory long-term post-EVAR surveillance 2
• Patients with anatomy unsuitable for EVAR (e.g., extensive mural thrombus covering >90% of proximal neck circumference increases endoleak and migration risk) 3
• Young patients with long life expectancy where durability is paramount 2

Technical considerations for EVAR: Stent-graft diameter should be oversized by 10-20% relative to the aortic diameter at the proximal neck 3. Completion angiography must confirm absence of endoleak and patency of all components 3

Medical Management

All AAA patients require optimal cardiovascular risk management to reduce major adverse cardiovascular events, which far exceeds the risk of aneurysm rupture in small AAAs. 1, 2, 4

Essential components:

• Smoking cessation (most critical modifiable risk factor) 1, 2
• Blood pressure control 4
• Statin therapy reduces cardiovascular mortality and may slow AAA growth 4
• Avoid fluoroquinolones unless compelling indication with no alternative (associated with increased aortic events) 1, 2

Beta-blockers, ACE inhibitors, and angiotensin receptor blockers do not affect AAA growth but may be indicated for comorbidities 4. No drug therapy has been convincingly shown to limit AAA growth in randomized controlled trials 5

Post-Intervention Surveillance After EVAR

At 30 days post-EVAR, imaging with CCT plus DUS is required to assess intervention success. 3, 2

Follow-up schedule:

• 1 month post-operatively 3, 2
• 12 months post-operatively 3, 2
• Yearly until fifth post-operative year 3, 2

Re-intervention is required immediately for Type I or Type III endoleaks to achieve seal and prevent rupture. 3, 2

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. 2

• Administer intravenous beta-blockers as first-line anti-impulse therapy, targeting heart rate 60-80 bpm and systolic BP <120 mmHg 2
• For hemodynamically stable patients, obtain CT imaging to evaluate suitability for endovascular repair before proceeding 2
• Mortality for ruptured AAA is 65-85% 6