Endovascular Stent Grafts for Disorders of the Thoracic Aorta

POLICY NUMBER

A.7.01.86

DESCRIPTION

Thoracic endovascular aortic repair (TEVAR) involves the percutaneous placement of a stent graft in the descending thoracic or thoracoabdominal aorta. It is a less invasive alternative than open surgery for the treatment of thoracic aortic aneurysms (TAAs), dissections, or rupture, and thus has the potential to reduce the morbidity and mortality of open surgery. Endovascular stenting may also be an alternative to medical therapy for treating thoracic aortic aneurysms or thoracic aorta dissections.

Thoracic Aortic Aneurysms

Aortic aneurysms are arterial dilations associated with age, atherosclerosis, and hypertension, as well as some congenital connective tissue disorders. The likelihood of significant sequelae of aortic aneurysm depends on the location, size, and underlying disease state. Left untreated, these aneurysms tend to enlarge over time, increasing the risk of rupture or dissection. Of greatest concern is the tendency for aortic aneurysms to rupture, with severe consequences including death. Another significant adverse occurrence of aortic aneurysm is aortic dissection, in which an intimal tear permits blood to enter the potential space between the intima and the muscular wall of the aorta. Stable dissections may be managed medically; however, dissections that impinge on the true lumen of the aorta or occlude branching vessels are a surgical emergency.

Treatment

Indications for the elective surgical repair of aortic aneurysms are based on estimates of the prognosis of the untreated aneurysm balanced against the morbidity and mortality of the intervention. The prognosis of thoracic aortic aneurysm (TAA) is typically reported regarding the risk of rupture according to size and location (ie, the ascending or descending or thoracoabdominal aorta). While several studies have estimated the risk of rupture of untreated aneurysms, these studies have excluded patients who underwent surgical repair; therefore, the true natural history of thoracic aneurysms is unknown. Clouse and colleagues performed a population-based study of TAA diagnosed in Minnesota, between 1980 and 1994. A total of 133 patients were identified; the primary clinical endpoints were cumulative rupture risk, rupture risk as a function of aneurysm size, and survival. The cumulative risk of rupture was 20% after 5 years. The 5-year risk of rupture as a function of aneurysm size at recognition was 0% for aneurysms less than 4 cm in diameter, 16% for those 4 to 5.9 cm, and 31% for aneurysms 6 cm or more. Interestingly, 79% of the ruptures occurred in women. Davies and colleagues reported on the yearly rupture or dissection rates in 721 patients with TAA. A total of 304 patients were dissection-free at presentation; their natural history was followed for rupture, dissection, and death. Patients were excluded from analysis once the operation occurred. Not surprisingly, the authors reported that aneurysm size had a profound impact on outcomes. For example, based on their modeling, a patient with an aneurysm exceeding 6 cm in diameter could expect a yearly rate of rupture or dissection of at least 6.9% and a death rate of 11.8%. In a previous report, the authors suggested surgical intervention of a descending aorta aneurysm if its diameter measured 6.5 cm.

Surgical mortality and morbidity are typically subdivided into emergency and elective repair, with a focus on the incidence and risk of spinal cord ischemia, considered the most devastating complication, resulting in paraparesis or paraplegia. The operative mortality of surgical repair of aneurysm of the descending and thoracoabdominal aorta is estimated at 6% to 12% and 10% to 15%, respectively, while mortality associated with emergent repair is considerably higher. In elective cases, predictors of operative mortality include renal insufficiency, increasing age, symptomatic aneurysm, the presence of dissection, and other comorbidities, such as cardiopulmonary or cerebrovascular disease. The risk of paraparesis or paraplegia is estimated at 3% to 15%. Thoracoabdominal aneurysms, larger aneurysms, the presence of dissection, and diabetes are predictorsof paraplegia. A number of surgical adjuncts have been explored to reduce the incidence of spinal cord ischemia, including distal aortic perfusion, cerebrospinal fluid drainage, hypothermia with circulatory arrest, and evoked potential monitoring. However, the optimal protective strategy is still uncertain.

This significant mortality and morbidity risks make definitive patient selection criteria for repair of thoracic aneurysms difficult. Several authors have recommended an individual approach based on balancing the patients' calculated risk of rupture with their anticipated risk of postoperative death or paraplegia. However, in general, surgical repair is considered in patients with adequate physiologic reserve when the thoracic aneurysm measures from 5.5 to 6 cm in diameter or in patients with smaller symptomatic aneurysms.

Thoracic Aortic Dissection

Aortic dissection can be subdivided into type A, which involves the aortic arch, and type B, which is confined to the descending aorta. Dissections associated with obstruction and ischemia can also be subdivided into an obstruction caused by an intimal tear at branch vessel orifices, or by compression of the true lumen by the pressurized false lumen. Type B aortic dissections are classified by acuity (termed as complicated or uncomplicated) and chronicity and are summarized in the table below.

Aortic Dissection Acuity

Treatment

Type A dissections are usually treated surgically, while type B dissections are usually treated medically, with surgery indicated for serious complications, such as visceral ischemia, impending rupture, intractable pain, or sudden reduction in aortic size. It has been proposed that endovascular therapy can repair the latter group of dissections by redirecting flow into the true lumen. The success of endovascular stent grafts of abdominal aortic aneurysms has created interest in applying the same technology to the aneurysms and dissections of the descending or thoracoabdominal aorta.

As noted, type A dissections (involving the ascending aorta) are treated surgically. There is more controversy regarding the optimal treatment of type B dissections (ie, limited to the descending aorta). In general, chronic, stable type B dissections are managed medically, although some surgeons have recommended a more aggressive approach for younger patients in otherwise good health. When serious complications arise from a type B dissection (ie, shock or visceral ischemia), surgical intervention is usually indicated. Endovascular intervention has supplanted open repair or medical management alone as first-line treatment for complicated type B aortic dissection as a result of accumulated data indicating reduced morbidity and mortality.

Thoracic Aortic Rupture

Rupture of the thoracic aorta is a life-threatening emergency that is nearly always fatal if untreated. Thoracic artery rupture can result from a number of factors. Aneurysms can rupture due to progressive dilatation and pressure of the aortic wall. Rupture can also result from traumatic injury to the aorta, such as occurs with blunt chest trauma. Penetrating injuries that involve the aorta can also lead to rupture. Penetrating ulcers can occur in widespread atherosclerotic disease and lead to aortic rupture.

Treatment

Emergent repair of thoracic artery rupture is indicated in many cases in which there is free bleeding into the mediastinum and/or complete transection of the aortic wall. In some cases of aortic rupture, where the aortic media and adventitia are intact, watchful waiting with delayed surgical intervention is a treatment option. With the advent of thoracic endovascular aneurysm repair (TEVAR), the decision-making for intervention may be altered, as there may be a greater tendency to intervene in borderline cases due to the potential for fewer adverse events with TEVAR.

Thoracic Endovascular Aortic Repair

TEVAR is an alternative to open surgery. It has been proposed for prophylactic treatment of aneurysms that meet criteria for surgical intervention, as well as for patients in need of emergency surgery for rupture or complications related to dissection. The standard open surgery technique for TAA is open operative repair with graft replacement of the diseased segment. This procedure requires lateral thoracotomy, use of cardiopulmonary bypass, lengthy surgical procedures, and is associated with a variety of peri- and postoperative complications, with spinal cord ischemia considered the most devastating.

TEVAR is performed through a small groin incision to access the femoral artery, followed by delivery of catheters across the diseased portion of the aorta. A tubular stent graft composed of fabric and metal is then deployed under fluoroscopic guidance. The stent graft is then fixed to the proximal and distal portions of the aorta. Approximately 15% of patients do not have adequate femoral access; for them, the procedure can be performed using a retroperitoneal approach.

Potential complications of TEVAR are bleeding, vascular access site complications, spinal cord injury with paraplegia, renal insufficiency, stroke, and cardiopulmonary complications. Some of these complications are similar to those encountered with open repair (eg, paraplegia, cardiopulmonary events), and others are unique to TEVAR (eg, access site complications).

Outcome Measures

Controlled trials of specific patient groups treated with specific procedures are required to determine whether endovascular approaches are associated with equivalent or improved outcomes compared with surgical repair. For patients who are candidates for surgery, open surgical resection of the aneurysm with graft replacement is considered the criterion standard for treatment of aneurysms or dissections. Some patients who would not be considered candidates for surgical therapy (due to unacceptable risks) might be considered candidates for an endovascular graft. In this situation, the outcomes of endovascular grafting should be compared with optimal medical management. Comparative mortality rates are of high concern, as are the rates of serious complications such as the incidence of spinal cord ischemia.

A number of endovascular grafts have been approved by the U.S. Food and Drug Administration (FDA) for use in TAAs.

Endovascular Grafts Approved for Use in Thoracic Aortic Aneurysms

PMA: premarket approval.

The Gore TAG® Thoracic Endoprosthesis is indicated for endovascular repair of aneurysms of the descending thoracic aorta. Use of this device requires patients to have adequate iliac/femoral access, aortic inner diameter in the range of 23 to 37 mm, and 2 cm or more non-aneurysmal aorta proximal and distal to the aneurysm. In 2012, the FDA expanded the indication for the Gore TAG® system to include isolated lesions of the thoracic aorta. Isolated lesions refer to aneurysms, ruptures, tears, penetrating ulcers and/or isolated hematomas, but do not include dissections. Indicated aortic inner diameter is 16 to 42 mm, with 20 mm or more of nonaneurysmal aortic distal and proximal to the lesion.

The Zenith TX2® TAA Endovascular Graft was approved by the FDA through the premarket approval (PMA) process for the endovascular treatment of patients with aneurysms or ulcers of the descending thoracic aorta. Indicated aortic inner diameter ranges from 24 to 38 mm.

The Talent™ Thoracic Stent Graft System was approved by the FDA through the PMA process for the endovascular repair of fusiform and saccular aneurysms or penetrating ulcers of the descending thoracic aorta. Indicated aortic inner diameter ranges from 18 to 42 mm. The Talent Thoracic Stent Graft System was discontinued by the manufacturer and replaced with the Valiant™ Thoracic Stent Graft System.

The Relay® Thoracic Stent-Graft with Plus Delivery System was approved by the FDA through the PMA process for the endovascular repair of fusiform aneurysms and saccular aneurysms or penetrating atherosclerotic ulcers in the descending thoracic aorta in patients having appropriate anatomy, including:

• Iliac or femoral access vessel morphology that is compatible with vascular access techniques, devices, and/or accessories

• Nonaneurysmal aortic neck diameter in the range of 19 to 42 mm

• Nonaneurysmal proximal aortic neck length between 15 and 25 mm and nonaneurysmal distal aortic neck length between 25 and 30 mm, depending on the diameter stent graft required.

The Valiant™ Thoracic Stent Graft with the Captivia® Delivery System was approved by the FDA for isolated lesions of the thoracic aorta. Isolated lesions refer to aneurysms, ruptures, tears, penetrating ulcers, and/or isolated hematomas, but not dissections. Indicated aortic diameter is 18 to 42 mm for aneurysms and penetrating ulcers, and 18 to 44 mm for blunt traumatic injuries. In 2014, the FDA expanded the indication for this graft and delivery system to include all lesions of the descending thoracic aorta, including type B dissections. The Valiant graft is intended for the endovascular repair of all lesions of the descending aorta in patients having appropriate anatomy, including:

• Iliac/femoral access vessel morphology compatible with vascular access techniques, devices, and/or accessories;

• Nonaneurysmal aortic diameter ranging from 18 to 42 mm (fusiform and saccular aneurysms/penetrating ulcers), 18 to 44 mm (blunt traumatic aortic injuries), or 20 to 44 mm (dissections) and;

• Nonaneurysmal aortic proximal and distal neck lengths of 20 mm or more (fusiform and saccular aneurysms/penetrating ulcers), and landing zone of 20 mm or more proximal to the primary entry tear (blunt traumatic aortic injuries, dissection). The proximal extent of the landing zone must not be dissected.

The expanded approval was based on the Medtronic Dissection Trial, a prospective, nonrandomized study that evaluated the performance of the Valiant stent graft for acute, complicated type B dissection, which included 50 patients enrolled at 16 sites.

The Valiant Navion™ is a next generation thoracic stent graft system with a modified design of the Valiant Thoracic Stent Graft with Captivia Delivery System. However, unused Valiant Navion thoracic stent graft systems were voluntarily recalled by the manufacturer (Medtronic) in February 2021 due to endoleaks, stent fractures, and stent ring enlargement. The recall occurred due to results of the Valiant Evo Global Clinical Trial which found 3 patients with stent fractures, 2 of whom had confirmed type IIIb endoleaks, and 1 patient death. Further investigation by an independent imaging laboratory found 7 of 87 patients with stent ring enlargement. The manufacturer is conducting further analysis.

Other devices are under development, and in some situations, physicians have adapted other commercially available stent grafts for use in the thoracic aorta.

POLICY

Endovascular stent grafts using devices approved by the U.S. Food and Drug Administration may be considered medically necessary for the following conditions:

• Descending thoracic aortic aneurysms used according to FDA-approved specifications (see Policy Guidelines).

• Acute, complicated (organ or limb ischemia or rupture) Type B thoracic aortic dissection.

• Traumatic descending aortic tears or rupture.

Endovascular stent grafts are considered investigational for the treatment of descending aortic disorders that do not meet the above criteria, including but not limited to uncomplicated aortic dissection (see Policy Guidelines).

Endovascular stent grafts are considered investigational for the treatment of ascending aortic disorders, including but not limited to thoracic aortic arch aneurysms.

POLICY EXCEPTIONS

None

POLICY GUIDELINES

The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member's specific benefit plan language.

Endograft Placement

Endograft placement relies on nonaneurysmal aortic segments proximal and distal to the aneurysm and/or dissection for anchoring, and a maximal graft diameter that varies by device. For example, the Gore TAG® endoprosthesis is approved by the U.S. Food and Drug Administration (FDA) for “≥2 cm non-aneurysmal aorta proximal and distal to the aneurysm" and an “aortic inner diameter of 23–37 mm.” The Zenith TX2® device is approved by the FDA for non-aneurysmal aortic segments “of at least 25 mm in length” and a “diameter measured outer wall to outer wall of no greater than 38 mm and no less than 24 mm.”

Uncomplicated Type B Aortic Dissection with Indication for Intervention

Guidelines generally suggest medical management for most patients with uncomplicated type B aortic dissection. However, guidelines by the American College of Cardiology/American Heart Association (ACC/AHA) and Society of Thoracic Surgeons/American Association for Thoracic Surgery suggest that early, pre-emptive intervention may be considered in patients with uncomplicated acute type B aortic dissection who have high-risk features. The high-risk criteria suggested by ACC/AHA are: maximal aortic diameter >40 mm, false-lumen diameter >20-22 mm, entry tear >10 mm, entry tear on lesser curvature, increase in total aortic diameter of >5 mm between serial imaging studies, bloody pleural effusion, imaging-only evidence of malperfusion, refractory hypertension despite >3 different classes of antihypertensive medications at maximal recommended or tolerated doses, refractory pain persisting >12 hours despite maximal recommended or tolerated doses, or need for readmission. In patients with an indication for early intervention, guidelines suggest endovascular repair may be preferred for patients with suitable anatomy but who are at high risk for complications of open repair due to comorbidities.

Medically Necessary is defined as those services, treatments, procedures, equipment, drugs, devices, items or supplies furnished by a covered Provider that are required to identify or treat a Member's illness, injury or Mental Health Disorders, and which Company determines are covered under this Benefit Plan based on the criteria as follows in A through D:

A.  consistent with the symptoms or diagnosis and treatment of the Member's condition, illness, or injury; and

B.  appropriate with regard to standards of good medical practice; and

C.  not solely for the convenience of the Member, his or her Provider; and

D.  the most appropriate supply or level of care which can safely be provided to Member. When applied to the care of an Inpatient, it further means that services for the Member's medical symptoms or conditions require that the services cannot be safely provided to the Member as an Outpatient.

For the definition of medical necessity, “standards of good medical practice” means standards that are based on credible scientific evidence published in peer-reviewed medical literature generally recognized by the relevant medical community, and physician specialty society recommendations, and the views of medical practitioners practicing in relevant clinical areas and any other relevant factors. BCBSMS makes no payment for services, treatments, procedures, equipment, drugs, devices, items or supplies which are not documented to be Medically Necessary. The fact that a Physician or other Provider has prescribed, ordered, recommended, or approved a service or supply does not in itself, make it Medically Necessary.

Investigative is defined as the use of any treatment procedure, facility, equipment, drug, device, or supply not yet recognized as a generally accepted standard of good medical practice for the treatment of the condition being treated and; therefore, is not considered medically necessary. For the definition of Investigative, “generally accepted standards of medical practice” means standards that are based on credible scientific evidence published in peer-reviewed medical literature generally recognized by the relevant medical community, and physician specialty society recommendations, and the views of medical practitioners practicing in relevant clinical areas and any other relevant factors. In order for equipment, devices, drugs or supplies [i.e, technologies], to be considered not investigative, the technology must have final approval from the appropriate governmental bodies, and scientific evidence must permit conclusions concerning the effect of the technology on health outcomes, and the technology must improve the net health outcome, and the technology must be as beneficial as any established alternative and the improvement must be attainable outside the testing/investigational setting.

POLICY HISTORY

7/2003: Approved by Medical Policy Advisory Committee (MPAC).

4/20/2005: Hyperlink to Endovascular Grafts for Abdominal Aortic Aneurysms deleted.

3/23/2006: Coding updated. CPT4 2006 revisions added to policy.

5/18/2006: Policy revised. Revisions approved by Medical Policy Advisory Committee (MPAC).

6/22/2006: Code reference section updated, all CPT codes moved from non-covered table to covered table. CPT code 33891 added to covered table. ICD-9 procedure code 39.73 added to covered table.

8/19/2009: Policy reviewed, no changes.

05/09/2011: Policy description revised to add additional FDA-approved devices: Zenith 2X2® device and Talent™ Thoracic Stent Graft System. The first policy statement was revised to indicate that endovascular stent grafts may be considered medically necessary for the treatment of descending thoracic aortic aneurysms using devices approved by the U.S. Food and Drug Administration for their approved specifications. The approved specifications for each device were added to the Policy Guidelines section.

09/23/2011: Policy statement revised to indicate that thoracic endovascular aneurysm repair may be considered medically necessary for complicated Type B dissections.  

09/25/2012: Policy reviewed; no changes.

10/14/2013: Treatment of rupture of the descending thoracic aorta added as medically necessary. Investigational policy statement expanded to include any thoracic aortic lesions that do not meet the above criteria, including but not limited to thoracic aortic arch aneurysms. Deleted outdated references from the Sources section.

08/25/2014: Policy titled changed from "Endovascular Stent Grafts for Thoracic Aortic Aneurysms" to "Endovascular Stent Grafts for Disorders of the Thoracic Aorta." Policy description updated regarding thoracic aortic aneurysms, thoracic aortic dissection, thoracic aortic rupture, TEVAR, and available devices. Policy statement unchanged. Policy guidelines updated.

08/25/2015: Code Reference section updated to add ICD-10 codes. Added ICD-9 diagnosis codes 441.01 and 441.03.

11/03/2015: Policy description updated. Policy statements unchanged. Policy guidelines section updated to add medically necessary and investigative definitions.

05/31/2016: Policy number A.7.01.86 added.

08/17/2016: Policy description updated. Policy statements unchanged.

09/30/2016: Code Reference section updated to add the following new ICD-10 procedure codes: 02VW3EZ, 02VW3FZ, 02VW4EZ, 02VW4FZ, 02VX3DZ, 02VX3EZ, 02VX3FZ, 02VX4DZ, 02VX4EZ, and 02VX4FZ.

07/06/2017: Policy description updated regarding devices. Policy statements unchanged.

06/21/2018: Policy description updated regarding outcome measures. Policy statements revised for clarity. Medically necessary criteria revised to change "treatment of rupture of the descending thoracic aorta" to "traumatic descending aortic tears or rupture." Investigational statement divided into two statements addressing descending and ascending aortic disorders.

12/18/2018: Code Reference section updated to add new CPT code 33866, effective 01/01/2019.

06/10/2019: Policy reviewed; no changes.

07/08/2020: Policy description updated regarding devices. Policy statements unchanged.

08/24/2021: Policy description updated regarding devices. Policy statements unchanged. Policy Guidelines updated to change "Nervous/Mental Conditions" to "Mental Health Disorders" and "Medically Necessary" to "medical necessity."

07/15/2022: Policy description updated. Policy statements unchanged.

09/26/2022: Code Reference section updated to add new ICD-10 diagnosis codes I71.010, I71.011, I71.012, I71.019, I71.10, I71.11, I71.12, I71.13, I71.20, I71.21, I71.22, I71.23, I71.50, I71.51, I71.52, I71.60, I71.61, and I71.62, effective 10/01/2022.

09/29/2023: Code Reference section updated to revise the code description of ICD-10 diagnosis codes I71.51, I71.52, I71.61, and I71.62, effective 10/01/2023.

11/17/2023: Policy description updated regarding aortic dissection acuity. Policy statements unchanged. Policy Guidelines updated regarding uncomplicated Type B aortic dissection with indication for intervention. Code Reference section updated to remove deleted ICD-10 diagnosis codes I71.01, I71.1, I71.2, I71.5, and I71.6.

10/17/2024: Policy reviewed; no changes.

10/01/2025: Code Reference section updated to add new ICD-10 procedure code 02UW3LZ.

01/01/2026: Code Reference section updated to add new CPT codes 33882 and 35602.

01/15/2026: Code Reference section updated to revise the code descriptions for CPT codes 33880, 33881, 33883, and 33886. Effective 01/01/2026.

SOURCE(S)

Blue Cross Blue Shield Association policy # 7.01.86

CODE REFERENCE

This may not be a comprehensive list of procedure codes applicable to this policy.

The code(s) listed below are ONLY medically necessary if the procedure is performed according to the "Policy" section of this document. 

Covered Codes

CPT copyright American Medical Association. All rights reserved. CPT is a registered trademark of the American Medical Association.