“We have to work together to pool data that demonstrate equivalence or superiority to open surgical repair,” Gustavo Oderich (University of Texas Health Science Center at Houston, Houston, USA) said of endovascular thoracoabdominal aortic aneurysm (TAAA) repair at this year’s European Society for Vascular Surgery (ESVS) annual meeting (20–23 September, Rome, Italy). He stressed that while the technique is “here to stay,” it is one that will require international, multicentre collaboration in order to be seen as on a par with, or even superior to, the current “gold standard” of open repair.
Oderich delivered these key messages as part of his Nicolai Volodos honorary lecture at ESVS 2022, and Volodos’s pioneering work in the endovascular space formed the backdrop to his presentation. “I got quite philosophical when preparing this talk and wondering about the difficulties that Dr Volodos encountered while doing research under the Soviet Union,” Oderich said. “Volodos has described that he was unable to borrow from other surgeons’ experiences, or receive critical evaluation or comments from others. International conferences, discussions with other physicians, input from engineers—all of these factors that are so important to the creation of the devices that we rely on in the endovascular era—he was not privy to any of this.”
Despite the confines within which Volodos worked, Oderich remarked that he was a “true pioneer” in the endovascular field, carrying out many “firsts”. He noted, for example, that Volodos performed the first thoracic endovascular repair, and also the first hybrid arch repair.
Now, three decades later, Oderich remarked that the vascular community has “embraced” endovascular therapy in many areas of the aorta and for a variety of pathologies, ranging from aneurysms to dissections. “However,” he noted, “there are areas of the world where endovascular repair of TAAAs is still not considered the first line of treatment”.
What do the data say?
Society clinical practice guidelines on aortic disease, which Oderich noted are being updated and will be published later this year, state that open thoracoabdominal aortic repair “remains the gold standard” for low- and intermediate-risk patients, at least in the USA. The reason for this, the presenter believes, comes down to the data that are currently available. The data on endovascular repair mostly come from single centres, or series with relatively short follow-up that are “often plagued with high reintervention rates,” he said.
With this in mind, Oderich put forward the key question: “What is the benchmark that we have to compare to, to be able to say—at some point—that endovascular is truly the first line of therapy?”
The speaker first considered the question of mortality. He noted that, despite many advances in critical care and surgical techniques, the mortality rate “in the best hands” for open surgical thoracoabdominal repair averages about 10% for an extent II thoracoabdominal aneurysm. However, the speaker highlighted that only one third of these patients are actually treated in high-volume centres. The majority are treated in mid- or low-volume centres where the mortality is “substantially higher” than it is in high-volume centres, averaging 20%.
He also pointed out other factors in addition to mortality that must be considered. “These patients are subjected to a very high rate of life-changing complications, notably respiratory failure, dialysis, still spinal cord injury, and mortality,” he informed ESVS attendees. Since the era of Stanley Crawford, however Oderich did say that there is one area in which there have been “substantial improvements”: paraplegia and spinal cord injury. “Now, with distal perfusion, the rates of paraplegia have gone down from 30% to 5% and 4% in contemporary series,” he detailed.
Durability is one of the frequently cited reasons why many people still believe open surgery should be the first line of therapy, Oderich stated, citing freedom from redo aortic operation rates of 90–95% at five to 10 years in open surgical series. However, he stressed that redo aortic surgery is not the same as secondary intervention. “We should hold open surgery to the same standard as we do for endovascular,” he remarked. “Secondary intervention implies any secondary procedure that is associated or triggered with the index operation and that includes not only redo aortic surgery but target vessel problems and other non-aortic problems. If we look carefully at open surgical series, the weight of these problems is not low, and in fact many of them carry substantially higher morbidity and risk.”
Oderich also referenced his own, ongoing work in this area. In a series of 500 thoracoabdominal aneurysms, he and his team demonstrated the benefits of endovascular versus open approaches for known aortic procedures. “In the area of aortic interventions,” he summarised, “endovascular does worse, but when we look at freedom from any secondary intervention, in fact, endovascular has done slightly better than open”.
The presenter also mentioned the US Aortic Research Consortium, which he described as “one of the neatest” collaborative efforts in this field of research. “[The project] really allows us to accrue patients in a rapid manner and at some point soon we hope to start doing prospective, randomised studies,” he said, mentioning that enrolment is now up to over 2,700 patients in the USA.
Oderich’s message at this point was hopeful: “We can achieve very low mortality rates [with endovascular repair], in the single digits, despite the fact that we still have a lot to learn from this technique.”
New technologies show “a lot of promise”
The presenter also addressed technological developments in the endovascular field, noting for example the potential of artificial intelligence to detect which patients are going to be at high risk of failure. He referenced some collaborative work that he and his team at the University of Texas are doing with researchers from the University of Stanford (Stanford, USA)—specifically a case-controlled study involving analysis of cases that failed versus cases with similar anatomy that did not fail by carrying out computational fluid analysis that allows the researchers to scale the haemodynamics, pressure, and flow rates.
New technologies also show potential in addressing the issue of radiation, which Oderich describes as the “bane” of endovascular operators’ existence. He showed a chart demonstrating that, since 2011, there has been a plateau in terms of fluoroscopy time in his cases. Technologies such as Centerline Biomedical’s Intra- Operative Positioning System (IOPS) and others show “a lot of promise” in radiation reduction, among other benefits, he informed ESVS attendees.
Collaboration is key
At the end of his lecture, Oderich stressed the importance of creating an environment in which researchers can work together. The International Aortic Research Consortium is an example of such a collaborative effort. “There is a lot of work to do in terms of funding, organisation, and structure, however we have already 2,600 or so cases in multiple centres and a number of projects that were delivered from this collaboration, and I can tell you a lot of these projects have led to change in my practice,” he said.
“Endovascular thoracoabdominal repair is here to stay,” Oderich concluded, noting, however, that there is work to be done. “We have to work together to pool data that demonstrate equivalence or superiority to open surgical repair, and we are not done yet. There is a lot of resistance to that in many parts of the world.”
Beyond collaborative data collection, Oderich stressed that the ultimate goal is to offer both open and endovascular options to all patients—as is the case at the University of Texas Health Science Center at Houston—with the patient involved in all decision-making related to their treatment.