What are the indications and management strategies for Endovascular Aortic Repair (EVAR) in patients with abdominal aortic aneurysm?

Endovascular Aortic Repair (EVAR) for Abdominal Aortic Aneurysm

Endovascular aortic repair (EVAR) is recommended as the first-line treatment for patients with abdominal aortic aneurysm (AAA) who have suitable anatomy, with elective repair indicated when the AAA diameter reaches ≥55 mm in men or ≥50 mm in women. 1, 2

Indications for EVAR

Size Criteria

• Men: AAA diameter ≥55 mm
• Women: AAA diameter ≥50 mm
• Saccular aneurysm ≥45 mm
• Rapid growth: ≥5 mm in 6 months or ≥10 mm per year

Anatomical Considerations

For successful EVAR, favorable anatomy is required:

• Proximal neck length >10-15 mm
• Neck diameter <30 mm
• Neck angulation <60°
• Mural thrombus/calcification <90% of circumference
• Adequate iliac access vessels 1, 2

Note: More than 50% of patients have aneurysm morphology unsuitable for conventional EVAR 1

Patient Selection Factors

• EVAR is preferred for patients with:

  • Advanced age
  • Multiple comorbidities
  • Higher surgical risk
  • Reasonable life expectancy (>2 years) 2

• Contraindications:

  • Limited life expectancy (<2 years)
  • Unsuitable anatomy
  • Connective tissue disorders (e.g., Marfan syndrome, Loeys-Dietz syndrome) 1, 2

Pre-Procedural Assessment

Imaging

• CTA is the gold standard for pre-EVAR planning
• Evaluate:
  • Aneurysm size and morphology
  • Proximal and distal landing zones
  • Access vessel diameter and tortuosity
  • Branch vessel involvement
  • Concomitant femoro-popliteal aneurysms 1, 2

Management Strategies

Standard EVAR

• Indicated for infrarenal AAA with suitable neck anatomy
• Uses bifurcated or tubular stent-grafts 1, 3

Fenestrated EVAR (FEVAR)

• For aneurysms with inadequate neck length
• Uses fenestrations in the graft to maintain perfusion to visceral arteries 1, 2

Emergency EVAR (eEVAR)

• For ruptured AAA with suitable anatomy
• Preferred over open repair to reduce perioperative mortality and morbidity
• Requires established protocols for expeditious diagnosis and treatment 1, 4, 5

Perioperative Considerations

• 30-day mortality: 1.7% for EVAR vs 4.7% for open repair 6
• Reduced hospital stay compared to open repair
• Access site complications: hematoma, pseudoaneurysm
• Early technical success rate >90% 2

Post-EVAR Surveillance

Follow-up Schedule

• Initial imaging at 1 month post-procedure
• Follow-up at 6-12 months
• Annual surveillance for at least 5 years 1, 2

Imaging Modalities

• CTA at 1 month post-procedure
• Color Doppler ultrasound (with or without contrast) for annual surveillance
• CTA or MRI every 5 years if no abnormalities are documented 1

Complications and Management

Endoleaks

• Most common complication of EVAR
• Types:
  1. Type I: Seal failure at attachment sites (requires immediate correction)
  2. Type II: Retrograde flow from branch vessels (may seal spontaneously in ~50% of cases)
  3. Type III: Graft defect or component separation (requires immediate correction)
  4. Type IV: Graft porosity
  5. Type V: Endotension 1, 2

Other Complications

• Limb occlusion or stenosis
• Graft migration
• Aneurysm sac enlargement despite EVAR
• Renal dysfunction
• Secondary interventions (more common with EVAR: 9.8% vs 5.8% with open repair) 2, 6

Long-Term Outcomes

• Similar long-term all-cause mortality between EVAR and open repair
• Higher reintervention rates with EVAR (5.1% vs 1.7% for open repair)
• Chronic anticoagulation increases risk of reintervention, late conversion, and mortality 2

Special Considerations

• Patients unfit for open repair show no survival benefit with EVAR compared to no intervention 7
• Lifelong surveillance is mandatory after EVAR due to higher reintervention rates 1, 2

Common Pitfalls to Avoid

• Inadequate post-EVAR surveillance leading to missed endoleaks
• Failure to detect concomitant femoro-popliteal aneurysms
• Attempting EVAR in patients with unsuitable anatomy
• Neglecting to consider patient's life expectancy (EVAR not recommended if <2 years) 1, 2