The evidence base for endovascular stenting, primarily Endovascular Aneurysm Repair (EVAR) for abdominal aortic aneurysms (AAA) and Thoracic Endovascular Aortic Repair (TEVAR) for thoracic aneurysms, has evolved through several landmark randomized controlled trials (RCTs). While endovascular techniques offer clear perioperative advantages, long-term data highlight a “catch-up” phenomenon in mortality and a higher burden of reinterventions compared to open surgical repair (OSR).
1. Landmark Abdominal Trials (EVAR vs. OSR)
Four major RCTs—EVAR-1 (United Kingdom Endovascular Aneurysm Repair 1), DREAM (Dutch Randomised Endovascular Aneurysm Management), OVER (Open vs. Endovascular Repair of Abdominal Aortic Aneurysm), and ACE (Anevrysme de l’aorte abdominale, Chirurgie vs. Endoprothese) —form the backbone of the evidence for treating infrarenal AAAs.
- Short-term Advantage: All major trials demonstrated a significant reduction in 30-day perioperative mortality with EVAR compared to OSR.
- The “Catch-up” Phenomenon: Beyond 2–3 years, the initial survival benefit of EVAR disappears. Long-term follow-up (up to 15 years in EVAR-1) shows that all-cause mortality becomes identical between the two groups. This is largely due to late aneurysm-related deaths in the EVAR group, often from secondary ruptures or complications.
- Reinterventions: EVAR is associated with a significantly higher rate of reinterventions compared to OSR, primarily to manage endoleaks, graft migration, or limb occlusion.
2. Thoracic Evidence (TEVAR)
The evidence for TEVAR in thoracic aortic aneurysms (TAA) is primarily based on prospective registries and the Gore TAG pivotal trial, and Gore conformable TAG thoracic endoprosthesis (CTAG) trial, as RCTs comparing TEVAR to OSR are limited due to the high morbidity of open thoracic surgery.
- Superiority in Descending Aorta: TEVAR is now considered the first-line treatment for descending thoracic aortic aneurysms. It reduces perioperative mortality and significantly lowers the risk of paraplegia and respiratory failure.
- Thresholds for Repair: Evidence supports intervention at a diameter of ≥5.5 cm for TEVAR in the descending aorta, though individual risk factors and growth rates (>1 cm/year) also trigger repair.
3. Current Guidelines and Recommendations
The 2024 European Society for Vascular Surgery (ESVS) guidelines provide the most contemporary synthesis of evidence.
- Patient Selection: OSR is recommended as the first-choice treatment for fit, younger patients (e.g., age <70) with a long life expectancy due to its superior long-term durability. EVAR is preferred for older, frailer patients or those with significant comorbidities. But EVAR 2 trial which is the only RCT evaluating frail patients not suitable for OSR concluded that EVAR does not increase overall life expectancy in patients ineligible for open repair but may reduce aneurysm related mortality.
- Complex Anatomy: For juxtarenal or pararenal aneurysms, Fenestrated EVAR (FEVAR) and Branched EVAR (BEVAR) are increasingly supported by high-quality registry data, showing lower mortality than open complex repair in high-risk patients.
- Institutional Volume: Guidelines now strongly recommend that centers perform at least 30 AAA repairs annually (minimum 15 EVAR and 15 OSR) to maintain optimal clinical outcomes.
4. Key Complications and Surveillance
The long-term success of endovascular stenting is contingent upon lifelong surveillance to detect “Achilles’ heel” issues:
- Endoleaks: Type I and Type III require urgent reintervention to prevent rupture. Type II is common and only requires treatment if the aneurysm sac expands.
- Sac Expansion: Post-EVAR sac growth is a surrogate marker for failure and a high-risk indicator for late rupture.
References
Endovascular Repair of Aortic Aneurysm in Patients Physically Ineligible for Open Repair: EVAR 2 Trial.
Patel, R., Sweeting, M. J., Powell, J. T., & Greenhalgh, R. M. (2016). Endovascular versus open repair of abdominal aortic aneurysm in 15-years’ follow-up of the UK endovascular aneurysm repair trial 1 (EVAR trial 1): a randomised controlled trial. The Lancet, 388(10058), 2366–2377.
Powell, J. T., Sweeting, M. J., Ulug, P., Blankensteijn, J. D., Lederle, F. A., Becquemin, J. P., & Greenhalgh, R. M. (2017). Meta-analysis of individual-patient data from EVAR-1, DREAM, OVER and ACE trials comparing outcomes of endovascular or open repair for abdominal aortic aneurysm over 5 years. British Journal of Surgery, 104(3), 166–178.
Schermerhorn, M. L., Buck, D. B., O’Malley, A. J., Curran, T., McDonald, J. C., Huang, C. L., Cotterill, P., & Landon, B. E. (2015). Long-Term Outcomes of Abdominal Aortic Aneurysm in the Medicare Population. New England Journal of Medicine, 373(4), 328–338.
Wanhainen, A., Mani, K., Bown, M. J., de Borst, G. J., Debus, S., Dick, F., Frostegård, J., Kolbel, T., Loftus, I., Resch, T., & van Herzeele, I. (2024). Editor’s Choice — European Society for Vascular Surgery (ESVS) 2024 Clinical Practice Guidelines on the Management of Abdominal Aorto-Iliac Artery Aneurysms. European Journal of Vascular and Endovascular Surgery, 67(2), 192–331.