Decades of EVAR: Are We Making Progress?
Frank J. Criado, MD, FACS, FSVM, spoke about endovascular aneurysm repair at the 2018 International Symposium on Endovascular Therapy. Dr Criado is a vascular surgeon and endovascular specialist at MedStar Union Memorial Hospital in Baltimore, Maryland.
VDM: Could you briefly comment on the clinical trials that created the foundations for the current Standard of Care?
Dr Criado: These landmark trials supported and helped establish endovascular aneurysm repair (EVAR) as a valid and appealing treatment option for abdominal aortic aneurysm (AAA): UK EVAR 1 (patient enrollment from 1999 to 2004), DREAM (enrollment between the years 2000 and 2003), and OVER (enrollment 2002 to 2008). EVAR 1 was the largest and most impactful trial, as it established the current 5.5 cm indication threshold (and the “EVAR” acronym, which was promptly embraced universally). A 3- to 4-fold advantage in 30-day mortality over open repair (OR) emerged relatively quickly as the most significant advantage of the endovascular approach. But this advantage is lost after a few years, and we now know that the overall mortality is essentially identical when the outcomes of EVAR and OR are scrutinized over the long haul.
VDM: Those trials used early-generation stent-graft devices that are no longer available; please comment.
Dr Criado: Indeed, the landmark EVAR versus OR clinical trials are now considered “old studies,” as they were designed in the 1990s and all completed by the middle of the last decade. More significantly, they used early-generation technologies that have been superseded by — arguably — much better stent-graft devices. Would the outcomes be different if we were to repeat these studies using present-day technologies? I think most experts agree that results would be measurably better, and we have mounting evidence that tends to confirm such assertions (see below). The number of reinterventions is one important piece of this picture: in EVAR 1, there were 258 reinterventions performed in 165 patients after EVAR, whereas only 105 reinterventions were performed in 74 patients following OR. In essence, EVAR patients experienced twice the reintervention rate of their OR counterparts. In both the EVAR 1 and the Dutch trials, the highest number of reinterventions was recorded between 4 and 6 years after the index procedure. This, together with the well-known post-EVAR risks of sac expansion and a persistent (albeit small) rate of aneurysm sac rupture after endovascular repair, have led to the well-founded recommendation for lifelong imaging-based patient surveillance that remains a paramount principle in the field.
VDM: Can we gain further insight by looking at current global registries and attempt, if possible, to make a comparison with the historical EVAR evidence generated 2 decades ago?
Dr Criado: Analysis of patient outcomes in the very large (Medtronic-sponsored) ENGAGE Global Registry examining the performance of the Endurant stent-graft in real-world EVAR-practice scenarios has emerged as an important window into the issue of how advanced current-generation devices can have an impact on and improve outcomes. And especially so in terms of reducing late failures and the number of reinterventions after EVAR. Both EVAR 1 and ENGAGE had the same endpoints, namely complication and reintervention rates, all-cause mortality, and aneurysm-related mortality. In EVAR 1, the complication rate for the EVAR group was 41% at 4 years, compared with 9% in the open group. The EVAR reintervention rate was 20% compared with 6% in the open group. The 4-year results for ENGAGE showed a 30% complication rate for EVAR (or 11% lower than with the first-generation devices in EVAR 1) and a 13% reintervention rate (7% lower than in EVAR 1). In EVAR 1, there was no difference in all-cause mortality (26% for EVAR versus 29% for OR) and only a 3% difference for aneurysm-related mortality (4% for EVAR versus 7% for open repair). In ENGAGE, although there was no difference in all-cause mortality (24%), aneurysm-related mortality was only 1.6% (versus 3.5% in EVAR 1), which is a 46% reduction. Furthermore, the rate of death from rupture after endovascular repair was 0.9% in EVAR 1, compared with 0.5% in ENGAGE.
VDM: In addition to newer and better devices, operator experience and other factors have improved as well. Might some of these factors contribute to better outcomes?
Dr Criado: EVAR experience and caseloads have grown exponentially over the last several years, and expertise has correspondingly increased. However, it is worth noting that at the individual operator’s level, caseload (yearly number of EVAR procedures) does not appear to have as big an impact on mortality and complication as it does in the case of OR — perhaps related to the inherently very low operative mortality risk of endovascular repair (between 0% and 1% in most reports today).
VDM: How big of a problem is off-label use and “pushing the envelope” that we hear so much about?
Dr Criado: Big problems indeed! The current trend (at least in the United States) of offering EVAR to “almost every AAA patient” has led to a situation in which off-label use occurs quite frequently, resulting unquestionably in compromised outcomes and outright bad results as we now know from some landmark literature reports of the last several years. And I must say, this situation is likely to continue in the foreseeable future.
VDM: Any additional closing comments?
Dr Criado: Treatment of complex AAA, particularly aneurysms with a bad/short/absent proximal neck, seems to be on the rise. I would anticipate fenestrated/branched repair becoming the predominant choice for the majority of these moving forward, but the evolution will be slow and somewhat difficult because of the resource-intensive nature of such technologies. Essentially, it is going to take the next generation of vascular and endovascular surgeons to come into the picture. Many of them are currently training at centers of excellence where such complex EVAR procedures are now being performed almost daily. Alongside fenestrated and branched grafts, increasing attention, and even on-label indication regulatory approval have been seen in developments with Ch-EVAR, parallel grafts, and Endo-Anchors. It would be fair to affirm they are here to stay, at least for the foreseeable future. Their practical utility is undeniable, although it must be said that in the minds of many experts, they represent inferior choices and “compromise solutions.” Lastly, in my opinion, open surgical repair must be rescued and brought back from near-abandonment, as it arguably remains an excellent treatment choice for medically fit patients presenting with complex endo-anatomy.
