Medical Necessity of Second Stage Procedure for Aberrant Right Subclavian Artery

Rationale for Medical Necessity

For extensive aneurysmal disease involving the aortic arch and descending aorta, repair is generally performed in a planned two-stage approach, with the second stage being essential for complete treatment 1, 2, 3
In the first stage, an open procedure is performed to create a bypass, followed by the second stage endovascular approach to complete the repair 3

Endovascular repair of descending thoracic aortic aneurysms with an FDA-approved endoprosthesis is considered medically necessary per CPB 0651 4
Thoracic endovascular aortic repair (TEVAR) is now an established technique in degenerative aneurysms and is recommended over open repair when anatomy is suitable 2, 5
For patients with degenerative or traumatic aneurysms of the descending thoracic aorta, endovascular stent grafting should be strongly considered when feasible (Class I recommendation, Level of Evidence B) 6

Coil embolization in the treatment of arterio-venous malformations/aneurysm is considered medically necessary per CPB 0856 4

Peripheral artery stenting is considered medically necessary for primary therapy for individuals with symptomatic posterior cerebral or cerebellar ischemia caused by subclavian artery stenosis who are at high-risk of surgical complications 4

Careful planning of the endovascular component is essential to prevent cerebrovascular complications 7

The two-stage hybrid approach is the standard of care for complex aortic pathology involving aberrant right subclavian artery 3
The second stage procedure is essential to complete the repair and prevent potentially fatal complications including rupture, dissection, or ischemic events 8
Without completion of the second stage, the patient would remain at high risk for complications related to the aberrant right subclavian artery and associated aortic pathology 8

For patients with chronic dissection and a descending thoracic aortic diameter approaching or exceeding 5.5 cm, intervention is recommended by the European Society of Cardiology, with a Level of Evidence B 9, 10
The use of fenestrated and branched endografts is recommended for chronic post-dissection thoracoabdominal aortic aneurysms when anatomically suitable, according to the European Heart Journal 9
Large intercostal artery fenestration is necessary to reduce spinal cord ischemia risk, which occurs in approximately 5% of thoracoabdominal repairs, as stated in the European Heart Journal 10

Endovascular stent grafting with fenestrated/branched grafts should be strongly considered when feasible for descending thoracic and thoracoabdominal aneurysms, with a Class I recommendation and Level of Evidence B from the American Heart Association 11, 10
Fenestrated-branched endovascular repair (F-BEVAR) for thoracoabdominal pathology after prior aortic surgery shows benefits over open repair, including avoiding thoracotomy incision, aortic cross-clamping, and need for extracorporeal circulation, as reported in Circulation 11

Progressive aneurysmal degeneration with rupture risk increasing as diameter approaches 60 mm (10% annual rupture risk at that threshold) is a concern if stage 2 is not completed, according to the European Heart Journal 10
The patient's slow but documented enlargement indicates active disease progression requiring completion of the planned repair, as stated in the European Heart Journal 9, 10

Underestimating access vessel requirements may lead to complications, and large-bore sheaths for fenestrated grafts may require surgical conduit in patients with peripheral arterial disease or small femoral vessels, as noted in Circulation 11
Continuous blood pressure management is crucial to prevent hypotension (spinal cord perfusion) or hypertension (endoleak risk) in the immediate post-procedure period, as recommended by the European Heart Journal 9