What is the recommended treatment for an infrarenal saccular aneurysm of 4.2 cm?

Management of Infrarenal Saccular Aneurysm of 4.2 cm

For an infrarenal saccular aneurysm of 4.2 cm, intervention to reduce the risk of rupture may be reasonable due to the saccular morphology, despite not meeting the standard size threshold for repair.1

Understanding Saccular Aneurysms vs. Standard Fusiform Aneurysms

Saccular aneurysms have different characteristics compared to the more common fusiform aneurysms:

• Saccular aneurysms are localized outpouchings of the aortic wall
• They may have a higher risk of rupture at smaller diameters than fusiform aneurysms
• The 2022 ACC/AHA guidelines specifically note that intervention for unruptured saccular AAAs may be reasonable (Class 2b recommendation) regardless of size 1

Decision-Making Algorithm for This Case

1. Assess aneurysm characteristics:

   • Size: 4.2 cm (below standard intervention threshold)
   • Type: Saccular (higher risk morphology)
   • Location: Infrarenal (standard repair options available)

2. Consider patient-specific factors:

   • Presence of symptoms (if symptomatic, repair is recommended regardless of size) 1
   • Growth rate (if ≥0.5 cm in 6 months, repair may be reasonable) 1
   • Gender (women have higher rupture risk at smaller diameters) 2

3. Determine management approach:

   • For asymptomatic 4.2 cm saccular aneurysm:
     • Consider intervention based on saccular morphology 1
     • If choosing surveillance, monitor more frequently than standard fusiform aneurysms

Surveillance vs. Intervention Options

If Choosing Surveillance:

• More frequent monitoring than standard recommendation for 3.5-4.4 cm fusiform aneurysms (every 12 months) 1, 2
• Consider 6-month surveillance intervals due to saccular morphology
• Use ultrasound for routine surveillance (cost-effective, no radiation) 2
• Monitor for:
  • Growth rate (≥0.5 cm in 6 months indicates need for intervention) 1
  • Development of symptoms
  • Changes in morphology

If Choosing Intervention:

• Both open and endovascular repair are viable options 1, 2
• Endovascular repair (EVAR) offers:
  • Lower perioperative morbidity and mortality
  • Shorter hospital stay
  • Less invasive procedure 2
• Open repair considerations:
  • Better for patients who cannot comply with long-term surveillance 1
  • Fewer long-term reinterventions 2

Important Caveats and Considerations

• Saccular morphology is believed to predispose aneurysms to rupture even at smaller diameters, though evidence is limited 3
• The standard size threshold for intervention (≥5.5 cm for men, ≥5.0 cm for women) applies primarily to fusiform aneurysms 1, 2
• If the patient has risk factors for rupture (female sex, continued smoking, uncontrolled hypertension, COPD), the case for earlier intervention strengthens 2
• The decision between EVAR and open repair should consider:
  • Patient's anatomical suitability for EVAR
  • Life expectancy
  • Ability to comply with post-EVAR surveillance 1, 2

Medical Management During Decision-Making

Regardless of the decision to intervene or monitor, implement these measures:

• Aggressive blood pressure control (target SBP 120-129 mmHg) 2
• Statin therapy to inhibit aneurysm expansion 2
• Smoking cessation (smoking doubles aneurysm expansion rate) 2
• Beta-blockers to reduce shear stress on the aortic wall 2