Andrea Amabile MD, Michel Pompeu Sá MD MSc MHBA PhD, Ibrahim Sultan MD
University of Pittsburgh
November 30, 2024
Abbreviations & Definitions
AATS – American Association for Thoracic Surgery
EACTS – European Association for Cardio-Thoracic Surgery
FET – Frozen elephant trunk
IMH – Intramural hematoma
LOE – Level of evidence
PAU – Penetrating aortic ulcer
STS – Society of Thoracic Surgeons
TBAD – Type B aortic dissection
Indications & Guidelines for Management by Grade/Stage of Disease
The most recent European Association for Cardio-Thoracic Surgery (EACTS)/Society of Thoracic Surgeons (STS) joint guidelines have provided a Class I recommendation to “view, interpret, and treat the aorta in the context of an organ.”1 With such perspective, both the classification and the management of acute aortic diseases have progressed to a degree of complexity that goes beyond the historic Stanford type A/type B classification, and which now also encompasses non-A/non-B aortic dissections, intramural hematomas (IMH; classified as type A and type B), and penetrating aortic ulcers (PAU).
This chapter will only focus on the indications and guidelines for the management of Type B aortic dissection (TBAD). Evidence from the 2024 EACTS/STS joint guidelines1 and the 2022 STS/American Association for Thoracic Surgery (AATS) clinical practice guidelines2 will be presented here.
For the 2024 EACTS/STS joint guidelines, aortic dissections can be classified based on the onset of the symptoms into acute (up to 14 days after dissection onset), subacute (5–90 days after dissection onset), and chronic (91 days after dissection onset and later). The 2022 STS/AATS guidelines use similar timestamps but slightly different terminology: hyperacute (<24 hours), acute (1–14 days), subacute (5–90 days), and chronic (>90 days).
Acute TBAD
Per the 2024 EACTS/STS joint guidelines, when approaching a patient with acute TBAD, the decision tree for its management must include four fundamental questions: 1) Is the dissection complicated? 2) Does the patient have any high-risk features? 3) Is the diameter of the ascending aorta <4.5 cm? 4) Is the patient anatomically suitable for thoracic endovascular aortic repair (TEVAR)?
A complicated TBAD dissection is a dissection with any of the following features: malperfusion of the spinal cord, gastrointestinal tract, the kidneys, or the limbs; pleural effusion containing blood; persistent pain; uncontrollable arterial hypertension; or contained or free aortic rupture.
In the case of an uncomplicated dissection, patients with high-risk features will be defined with any of the following morphologic criteria: primary entry tear >10 mm, located at the inner curvature, or located <20 mm in relation to the left subclavian artery; a false lumen with a diameter >22 mm; a descending thoracic aorta diameter >40 mm; high systolic antegrade flow volume in the false lumen with significant diastolic retrograde flow assessed by magnetic resonance imaging.
With these definitions in mind, the algorithm for the management of patients with acute TBAD can be summarized as follows (reproduced with permission from the EACTS/STS Guidelines1):
This guideline-directed evidence in support of the management of patients with acute TBAD can be summarized as follows:
| Recommendation | Class | Level | Reference |
|---|---|---|---|
| In patients with complicated acute TBAD and suitable anatomy, TEVAR is recommended. | I | B | 1, 3-7 |
| In patients with acute complicated TBAD with unsuitable anatomy for TEVAR, FET repair should be considered. | IIa | B | 1, 8, 9 |
| In acute TBAD with high-risk features, TEVAR should be considered in the subacute phase. | IIa | C | 1 |
| In patients with acute TBAD without high-risk features, optimal medical therapy, close monitoring and medical follow-up is recommended for emerging high-risk features. | I | B | 1, 10, 11 |
| TEVAR is indicated for complicated hyperacute, acute, or subacute TBADs with rupture and/or malperfusion and favorable anatomy for TEVAR. | I | B | 2 |
| Open surgical repair for complicated hyperacute, acute, or subacute TBADs should be considered for those patients with unsuitable anatomy for TEVAR. | IIa | B | 2 |
| Fenestration may be considered for complicated hyperacute, acute, or subacute TBADs. | IIb | C | 2 |
| A stepwise approach to the evaluation and treatment of acute/subacute uncomplicated TBAD should be applied that includes identification of the primary entry tear site location, definition of the proximity and distance of the dissection to the left subclavian artery, calibration of the maximum orthogonal aortic diameter, and confirmation of the lack of any organ malperfusion or other indications of complicated disease. | I | B | 2 |
| Optimal medical therapy is the recommended treatment for patients with uncomplicated TBAD. | I | B | 2 |
| Prophylactic TEVAR may be considered in patients with uncomplicated TBAD to reduce late aortic-related adverse events and aortic-related death. | IIb | B | 2 |
| Close clinical follow-up after hospital discharge is recommended for patients presenting with acute TBAD. | I | B | 2 |
Chronic TBAD
In patients with chronic TBAD, elective intervention should be considered in the setting of aneurysm dilatation (>55-60 mm), increasing rate of diameter (growth >10 mm/year), or symptoms (particularly pain or clinical evidence of malperfusion).12-15
The guidelines-directed evidence in support of the management of patients with chronic TBAD can be summarized as follows:
| Recommendation | Class | Level | Reference |
|---|---|---|---|
| Intervention is recommended in patients with chronic aortic dissection at a maximum aortic diameter of >55 mm without involvement of the ascending aorta. | I | B | 1, 16, 17 |
| In patients with heritable thoracic aortic disease with chronic aortic dissection, intervention at diameters >55 mm should be considered if the multidisciplinary aortic team makes the decision depending on the genotype, growth rate, family history, and other individual patient risk factors. | IIa | C | 1 |
| In patients with distal stent graft-induced new entry, treatment is recommended to prevent diameter progression. | I | C | 1 |
| Intervention at >50 mm should be considered in patients with chronic aortic dissection if the treatment includes a multistep procedure, such as arch replacement with FET followed by TEVAR. | IIa | C | 1 |
| Open surgical repair should be considered for patients with chronic TBAD with indications for intervention (unless comorbidities are prohibitive) or anatomy is not suitable for TEVAR. | IIa | B | 2 |
| TEVAR is reasonable for patients with chronic TBAD with an indication for intervention with suitable anatomy (i.e., adequate landing zone, absence of ascending or arch aneurysm) but who are at high risk for complications of open repair due to comorbidities. | IIa | B | 2 |
| TEVAR alone as sole therapy is not recommended in patients with chronic TBAD who have a large abdominal aortic aneurysm, an inadequate distal landing zone, and/or large distal reentry tears. | III | C | 2 |
Supporting Evidence for Current Indications & Guidelines
The INSTEAD trial4 randomized 140 patients with uncomplicated TBAD to either TEVAR plus optimal medical therapy (OMT) or OMT alone. The trial found no significant difference in all-cause mortality, aortic-related death, or dissection progression at the 2-year mark. As the first randomized study evaluating elective stent-graft placement in this population, it demonstrated that TEVAR did not confer a short-term survival or clinical benefit despite evidence of favorable aortic remodeling.
The INSTEAD-XL trial3 followed 140 patients with uncomplicated TBAD randomized to TEVAR plus OMT or OMT alone, extending outcomes to five years. While overall mortality remained similar between groups, the TEVAR group showed significantly lower aortic-related mortality and delayed disease progression. These findings suggested that in stable patients with suitable anatomy, preemptive TEVAR may improve long-term aorta-specific outcomes.
The ADSORB trial5 enrolled 61 patients with uncomplicated TBAD, randomizing them to TEVAR plus OMT or OMT alone. At one year, while there was no difference in survival, the TEVAR group demonstrated greater false lumen thrombosis and a significant reduction in false lumen diameter, suggesting early aortic remodeling.
Expert Commentary
The decision to perform a TEVAR in the setting of a complicated TBAD or a TBAD with high-risk features is supported by evidence and guidelines. Some of our prior work has demonstrated that a select patient population, despite not being complicated or having high-risk features, may have a survival and remodeling advantage with TEVAR in acute TBAD.18, 19
For example, meta-analyses have demonstrated that most studies were composed of populations without the thresholds established in the guidelines (in terms of aortic size) to trigger a recommendation for TEVAR. Additionally, regarding hematoma thickness, few populations met the criteria for the indication of TEVAR. We did not find the classic high-risk features to be modulating factors of the effects of TEVAR, which suggests that TEVAR may impart some remodeling and/or aortic-specific survival benefit in type B aortic syndromes regardless of the presence/absence of high-risk features.
Another aspect yet to be defined is the optimal timing to intervene in these cases. There seems to be a timing-specific difference20 in the outcomes of TEVAR for TBAD, pointing to the subacute phase as the optimal timing to achieve better long-term outcomes, but much of this data is historic and may not have a compelling basis in contemporary practice. Our practice is to intervene in the index admission. We are aggressive about revascularization of the left subclavian artery when anatomy and pathology necessitate zone 2 TEVAR. This is typically accomplished with left carotid-subclavian transposition or branch stenting of the left subclavian artery at the time of zone 2 TEVAR. The latter can be performed with laser fenestration or commercially available side-branch TEVAR, such as the GORE TBE (Thoracic Branch Endoprosthesis).
Sources
1. Czerny M, Grabenwöger M, Berger T, Aboyans V, Della Corte A, Chen EP, et al. EACTS/STS Guidelines for diagnosing and treating acute and chronic syndromes of the aortic organ. Eur J Cardiothorac Surg. 2024;65(2).
2. MacGillivray TE, Gleason TG, Patel HJ, Aldea GS, Bavaria JE, Beaver TM, et al. The Society of Thoracic Surgeons/American Association for Thoracic Surgery Clinical Practice Guidelines on the Management of Type B Aortic Dissection. Ann Thorac Surg. 2022;113(4):1073-92.
3. Nienaber CA, Kische S, Rousseau H, Eggebrecht H, Rehders TC, Kundt G, et al. Endovascular repair of type B aortic dissection: long-term results of the randomized investigation of stent grafts in aortic dissection trial. Circ Cardiovasc Interv. 2013;6(4):407-16.
4. Nienaber CA, Rousseau H, Eggebrecht H, Kische S, Fattori R, Rehders TC, et al. Randomized comparison of strategies for type B aortic dissection: the INvestigation of STEnt Grafts in Aortic Dissection (INSTEAD) trial. Circulation. 2009;120(25):2519-28.
5. Brunkwall J, Kasprzak P, Verhoeven E, Heijmen R, Taylor P, Alric P, et al. Endovascular repair of acute uncomplicated aortic type B dissection promotes aortic remodelling: 1 year results of the ADSORB trial. Eur J Vasc Endovasc Surg. 2014;48(3):285-91.
6. Liu D, Luo H, Lin S, Zhao L, Qiao C. Comparison of the efficacy and safety of thoracic endovascular aortic repair with open surgical repair and optimal medical therapy for acute type B aortic dissection: A systematic review and meta-analysis. Int J Surg. 2020;83:53-61.
7. Li FR, Wu X, Yuan J, Wang J, Mao C, Wu X. Comparison of thoracic endovascular aortic repair, open surgery and best medical treatment for type B aortic dissection: A meta-analysis. Int J Cardiol. 2018;250:240-6.
8. Kreibich M, Berger T, Morlock J, Kondov S, Scheumann J, Kari FA, et al. The frozen elephant trunk technique for the treatment of acute complicated Type B aortic dissection. Eur J Cardiothorac Surg. 2018;53(3):525-30.
9. Weiss G, Tsagakis K, Jakob H, Di Bartolomeo R, Pacini D, Barberio G, et al. The frozen elephant trunk technique for the treatment of complicated type B aortic dissection with involvement of the aortic arch: multicentre early experience. Eur J Cardiothorac Surg. 2015;47(1):106-14; discussion 14.
10. Estrera AL, Miller CC, 3rd, Safi HJ, Goodrick JS, Keyhani A, Porat EE, et al. Outcomes of medical management of acute type B aortic dissection. Circulation. 2006;114(1 Suppl):I384-9.
11. Muller M, Yau P, Pham A, Lipsitz EC, DeRose JJ, Cho JS, et al. A comparison of endovascular repair to medical management for acute vs subacute uncomplicated type B aortic dissections. J Vasc Surg. 2023;78(1):53-60.
12. Svensson LG, Kouchoukos NT, Miller DC, Bavaria JE, Coselli JS, Curi MA, et al. Expert consensus document on the treatment of descending thoracic aortic disease using endovascular stent-grafts. Ann Thorac Surg. 2008;85(1 Suppl):S1-41.
13. Zoli S, Etz CD, Roder F, Mueller CS, Brenner RM, Bodian CA, et al. Long-term survival after open repair of chronic distal aortic dissection. Ann Thorac Surg. 2010;89(5):1458-66.
14. Akin I, Kische S, Ince H, Nienaber CA. Indication, timing and results of endovascular treatment of type B dissection. Eur J Vasc Endovasc Surg. 2009;37(3):289-96.
15. Zafar MA, Chen JF, Wu J, Li Y, Papanikolaou D, Abdelbaky M, et al. Natural history of descending thoracic and thoracoabdominal aortic aneurysms. J Thorac Cardiovasc Surg. 2021;161(2):498-511.e1.
16. Bajona P, Quintana E, Schaff HV, Daly RC, Dearani JA, Greason KL, et al. Aortic arch surgery after previous type A dissection repair: results up to 5 years. Interact Cardiovasc Thorac Surg. 2015;21(1):81-5; discussion 5-6.
17. Wang H, Wagner M, Benrashid E, Keenan J, Wang A, Ranney D, et al. Outcomes of Reoperation After Acute Type A Aortic Dissection: Implications for Index Repair Strategy. J Am Heart Assoc. 2017;6(10).
18. Sá MP, Jacquemyn X, Van den Eynde J, Chu D, Serna-Gallegos D, Singh MJ, et al. Midterm Outcomes of Endovascular vs. Medical Therapy for Uncomplicated Type B Aortic Dissection: Meta-Analysis of Reconstructed Time to Event Data. Eur J Vasc Endovasc Surg. 2023;66(5):609-19.
19. Sá MP, Jacquemyn X, Tasoudis P, Dufendach K, Singh MJ, de la Cruz KI, et al. Five Year Results of Endovascular versus Medical Therapy in Acute Type B Aortic Intramural Haematoma: Meta-Analysis of Reconstructed Time to Event Data. Eur J Vasc Endovasc Surg. 2024;67(4):584-92.
20. Sá MP, Jacquemyn X, Brown JA, Ahmad D, Serna-Gallegos D, Arnaoutakis GJ, et al. Thoracic endovascular aortic repair for hyperacute, acute, subacute and chronic type B aortic dissection: Meta-analysis of reconstructed time-to-event data. Trends Cardiovasc Med. 2024;34(7):479-85.
