What is the management approach for suspected stent migration after Endovascular Aneurysm Repair (EVAR)?

Management of Stent Migration After EVAR

When stent migration is suspected after EVAR, immediately obtain CT angiography to confirm the diagnosis, as this is the gold standard imaging modality and duplex ultrasound will miss this critical complication. 1, 2

Diagnostic Confirmation

• CT angiography is mandatory for detecting stent migration, as duplex ultrasound—while excellent for endoleak detection—is fundamentally limited in its ability to identify migration, fracture, or stent position changes 1, 2
• MRI with accompanying plain abdominal radiograph is an acceptable alternative if CT is contraindicated, though the plain film component is essential to visualize metallic stent struts 1, 2
• Compare current imaging to the baseline 1-month post-EVAR CT to establish the degree of migration, as this reference point is critical for determining true versus artifactual migration 2, 3

Common Pitfall to Avoid

• Do not rely on duplex ultrasound alone when migration is suspected—this will delay diagnosis and appropriate intervention, as ultrasound cannot adequately characterize stent position 1, 2, 4

Risk Stratification

Once migration is confirmed, assess for:

• Aneurysm sac enlargement ≥10 mm, which mandates urgent intervention 2
• Associated endoleak (particularly Type I), which occurs with migration and significantly increases rupture risk 1
• Degree of migration and proximity to critical attachment zones 2
• Patient anatomy including mural thrombus and calcification covering >90% of proximal neck circumference, which represents high-risk anatomy 2

The clinical significance is substantial: migration occurs in 3-4% of patients by 4 years postoperatively and represents a major cause of late endograft failure, with late aortic rupture occurring in >5% of EVAR patients through 8 years of follow-up 1, 2, 3

Treatment Algorithm

First-Line: Endovascular Reintervention

Catheter-based endovascular techniques are the first treatment option for stent migration in contemporary practice 5:

• Percutaneous transluminal balloon angioplasty to secure the attachment site 5
• Stent-graft extension to re-establish adequate seal zones 5
• Placement of additional stent at the proximal attachment site 5
• Endostaples to secure the position of the proximal cuff to the primary endograft 5
• Large balloon-expandable stents to improve seal between components 5

Second-Line: Conversion to Open Repair

• Failed endovascular reintervention is the primary indication for late conversion to open surgical repair 2
• Open conversion should be considered when endovascular options are exhausted or anatomically unfeasible 2

Post-Intervention Surveillance

After successful reintervention:

• Obtain baseline CT imaging at 1 month to establish new reference position 2, 3
• If stable, transition to annual duplex ultrasound with cross-sectional imaging (CT or MRI) every 5 years 1, 3, 4
• Any abnormal findings on duplex ultrasound mandate immediate cross-sectional imaging to evaluate for recurrent migration 1, 3, 4
• Lifelong surveillance is necessary, as complications can occur many years after EVAR 3, 4

Intensified Surveillance Considerations

• Patients with high-risk anatomy (extensive mural thrombus/calcification) require more frequent monitoring 2
• Annual CT or MRI is appropriate for patients with abnormal findings or complex EVAR 1, 3

Critical Clinical Pearls

• Artifactual migration can occur due to variations in radiographic positioning between studies; errors increase with distance from midline and differences in craniocaudal centering, but consistent positioning to within 4 cm limits errors to 1.5 mm 6
• The traditional 6-month surveillance interval can be eliminated if the 1-month imaging shows no concerning findings 1, 3
• Migration with associated sac enlargement represents the highest-risk scenario requiring urgent intervention 1, 2