What is the role of stent (percutaneous endovascular stent) grafts in treating coarctation of the aorta?

Role of Stent Grafts in Treating Coarctation of the Aorta

Stent implantation is indicated as the preferred treatment for coarctation of the aorta in patients of sufficient size who can receive a stent that can be expanded to adult size (minimum 2 cm diameter) and who have a transcatheter systolic coarctation gradient >20 mm Hg. 1

Indications for Stent Implantation

Stent grafts are indicated in the following scenarios:

Class I Indications (Strong Recommendation)

• Recurrent coarctation with transcatheter systolic gradient >20 mm Hg in patients of sufficient size for safe stent placement 1
• Native or recurrent coarctation with significant anatomic narrowing causing hypertension 1
• Long-segment coarctation with transcatheter systolic gradient >20 mm Hg 1

Class IIa Indications (Reasonable to Consider)

• Initial treatment of native coarctation in patients with suitable anatomy where the stent can be expanded to adult size 1
• When balloon angioplasty has failed 1

Class IIb Indications (May Be Considered)

• Coarctation with gradient <20 mm Hg but with elevated left ventricular end-diastolic pressure and anatomic narrowing 1
• Coarctation with gradient <20 mm Hg but with significant aortic collaterals 1

Advantages of Stent Grafts Over Other Treatment Options

Stent implantation offers several advantages compared to balloon angioplasty alone or surgical repair:

1. Lower recurrence rates: Stenting provides superior short-term results compared to balloon angioplasty alone 1
2. Reduced aneurysm formation: Stents provide structural support that may reduce the risk of aneurysm formation compared to balloon angioplasty 1
3. Less invasive than surgery: Avoids thoracotomy and associated complications 1
4. Effective for complex anatomies: Can be used for long-segment coarctation and complex stenosis 2
5. Treatment of associated aneurysms: Covered stents can simultaneously treat coarctation and associated aneurysms 3

Patient Selection Considerations

The decision to use stent grafts should consider:

• Patient size: Patients should be of sufficient size for safe stent placement, typically >25 kg 4
• Ability to expand stent: The stent should be expandable to adult size (minimum 2 cm diameter) 1, 4
• Anatomic suitability: Evaluation of arch anatomy, length of coarctation, and proximity to branch vessels 4
• Previous interventions: Particularly valuable in recurrent coarctation after surgical repair 1

Outcomes and Follow-up

Stent implantation for coarctation demonstrates excellent outcomes:

• Immediate hemodynamic improvement: Studies show significant reduction in peak systolic gradient from 32-39 mmHg to 3-4 mmHg post-procedure 5, 6
• Sustained results: Mid-to-long-term follow-up shows maintained gradient reduction and improved vessel diameter 5, 6
• Low complication rates: Major complications occur in <5% of cases 5
• Blood pressure improvement: Significant reduction in systolic blood pressure at follow-up 6

Follow-up Recommendations

After stent implantation, patients require:

1. Regular imaging surveillance: CMR or CTA every 3-5 years to evaluate for complications including recoarctation, aneurysm, pseudoaneurysm, and stent fracture 1, 4
2. Blood pressure monitoring: Both upper and lower extremities, with consideration of ambulatory monitoring 1
3. Exercise testing: To evaluate for exercise-induced hypertension 1
4. Screening for intracranial aneurysms: Consider MR angiography or CTA as adults with coarctation have a 10% prevalence of intracranial aneurysms 1

Special Considerations

Small Children

While traditionally not recommended in small children, recent evidence suggests adult-sized stents can be successfully implanted in children as small as 5.5 kg, though with higher risk of access-related complications 7. These patients will require planned re-interventions as they grow.

Complex Coarctation

Stent repair has shown good results even in complex cases including:

• Complete aortic arch interruption
• Associated aneurysms
• Complex stenosis with tortuous anatomy
• Need for re-expansion in growing patients 2

Covered Stents

Particularly valuable for treating coexistent coarctation and aneurysm, or when there is concern about aortic wall integrity 3

Potential Complications

• Access site complications: Particularly in smaller patients 7
• Stent migration or fracture: May require reintervention 7
• Aortic wall injury: Including dissection or aneurysm formation
• Need for reintervention: Particularly in growing children 7

Stent grafts have emerged as an effective and durable treatment option for coarctation of the aorta, with excellent short and intermediate-term outcomes. Proper patient selection, technical expertise, and long-term surveillance are essential for optimal results.