What are the indications, pre‑operative imaging criteria, peri‑operative medication regimen, and follow‑up protocol for endovascular aneurysm repair (EVAR) of an infrarenal abdominal aortic aneurysm (AAA)?

Endovascular Repair of Abdominal Aortic Aneurysm (AAA)

For elective infrarenal AAA repair, EVAR is the preferred approach in patients with suitable anatomy and life expectancy >2 years, offering <1% peri-operative mortality compared to 4-5% with open repair, though it requires lifelong imaging surveillance and carries higher rates of late complications including secondary interventions (HR 2.1) and aneurysm-related death after 8 years (HR 5.12). 1, 2

Indications for EVAR

Size-Based Thresholds (Class I, Level A)

• Men: AAA diameter ≥5.5 cm warrants elective repair 1, 2
• Women: AAA diameter ≥5.0 cm warrants elective repair, as women have four-fold higher rupture risk at comparable diameters 3, 2

Additional Repair Indications

• Rapid growth: ≥10 mm per year or ≥5 mm in 6 months, even below size thresholds 1, 3, 2
• Symptomatic AAA: Abdominal or back pain attributable to the aneurysm, regardless of diameter 2
• Saccular morphology: Consider repair at ≥4.5 cm due to higher rupture risk 1, 3

Contraindications

• Life expectancy <2 years: Do not repair (Class III, Level B) 2
• Unsuitable anatomy: Patients not meeting anatomic criteria for available devices should be considered for open repair 1

Pre-Operative Imaging Protocol

Primary Imaging Modality

• Contrast-enhanced CT angiography (CTA) is mandatory for EVAR planning, providing complete aorto-iliac system assessment, true aneurysm diameter measurement, and thrombus burden evaluation 3, 4, 5
• Multiplanar reformatted images with centerline 3D software must be used to accurately measure diameter perpendicular to the longitudinal axis in tortuous vessels 2

Anatomic Assessment Requirements

• Proximal neck evaluation: Length, diameter, angulation, and thrombus burden (>90% circumferential thrombus increases type I endoleak and migration risk) 3, 5
• Iliac artery assessment: Diameter, tortuosity, calcification, and access vessel suitability 5
• Femoro-popliteal duplex ultrasound: Recommended as femoro-popliteal aneurysms coexist in up to 14% of AAA patients 3, 2

Device Selection Criteria

• Stent-graft oversizing: 10-20% relative to proximal neck diameter 3
• Bifurcated stent-grafts: Used in most cases 3
• Fixation strategy: Suprarenal versus infrarenal depending on device and neck anatomy 3
• Adherence to manufacturer's instructions for use (IFU) is mandatory (Class I, Level B-NR) 1

Peri-Operative Medication Regimen

Cardiovascular Risk Reduction (Class I, Level C)

• Smoking cessation: Most critical modifiable risk factor; use behavior modification, nicotine replacement, or bupropion 2, 6
• Intensive lipid management: Target LDL-C <55 mg/dL (<1.4 mmol/L) 2
• Blood pressure control: Optimize anti-hypertensive therapy pre-operatively 2, 6
• Single antiplatelet therapy: Low-dose aspirin if concomitant coronary artery disease present (OR 2.99 for cardiovascular event reduction) 2

Medications to Avoid

• Fluoroquinolones: Avoid unless compelling indication with no alternative, due to association with aneurysm complications 3, 2

Pre-Operative Assessment

• Vascular physician evaluation optimizes medication against atherosclerosis, uncontrolled hypertension, and peri-operative ischemic cardiac events at lower cost than standardized protocols 6
• Do NOT perform routine coronary angiography or systematic revascularization before AAA repair in chronic coronary syndrome patients (Class III, Level C) 2

Intra-Operative Technical Requirements

• Completion angiography: Must confirm absence of endoleak and patency of all components 3
• Immediate endoleak management: Type I and III endoleaks require immediate re-intervention to achieve seal 3, 2

Post-EVAR Surveillance Protocol (Lifelong)

Imaging Schedule (Class I)

Time Point	Imaging Modality	Purpose
30 days	CCT + DUS or contrast-enhanced ultrasound	Verify technical success [3,2]
12 months	CCT or DUS	Assess durability [2]
Years 1-5	Annual DUS or contrast-enhanced ultrasound	Monitor sac size & endoleaks [2]
>5 years	CCT or MRI every 5 years if DUS primary modality	Detect late complications [2]

Surveillance Rationale

• Duplex ultrasound: 95% accurate for sac diameter measurement and 100% specific for detecting type I and III endoleaks 2
• Lifelong surveillance is mandatory as late complications including rupture can occur many years after EVAR 2, 7
• Combining 30-day CTA with sac shrinkage >5 mm at 1 year provides optimal risk stratification (NPV ≥95% up to 4 years) 7

Endoleak Management

• Type I and III endoleaks: Re-intervene to achieve seal 3, 2, 8
• Type II endoleaks with aneurysm expansion: Treat 8
• Type II endoleaks without expansion: Continue surveillance 8

Emergency Management of Ruptured AAA

• EVAR preferred over open repair for patients with suitable anatomy (Class I, Level B), reducing peri-operative morbidity and mortality 1, 2
• Door-to-intervention time <90 minutes recommended (30-30-30 minute framework) 8
• Overall rupture mortality: 75-90% 2

Critical Pitfalls to Avoid

• Do not discontinue surveillance after EVAR: After 8 years, EVAR patients have increased aneurysm-related death (HR 5.12), rupture (OR 5), and rupture-related death (OR 3.6) compared to open repair 1
• Do not apply different size thresholds for EVAR versus open repair: Indications are identical based on diameter, growth rate, and symptoms 2
• Do not ignore poor surveillance compliance: Post-EVAR imaging compliance is only 45.6% at 5 years in real-world practice; smoking, alcohol use, and cardiac risk factors predict poor follow-up 9
• Do not treat outside IFU: Off-label use increases complication rates 1

Long-Term Outcomes

• 30-day mortality: EVAR 0.36% versus open repair 4-5% (OR 0.36; 95% CI 0.2-0.66) 1, 10
• 5-year survival: 89% in appropriately selected younger patients (<70 years) 10
• Secondary intervention rate: Higher with EVAR (HR 2.1; 95% CI 1.7-2.7) 1
• Late aneurysm-related mortality: Higher with EVAR after 8 years (HR 5.12; 95% CI 1.6-16.4) 1