Roger Greenhalgh (top left), Ian Loftus (top right), Lindsay Machan (bottom left), and Gustavo Oderich (bottom right)
A global audience tuned into the second session and inaugural aortic offering of CX 2020 LIVE. With registrations now well over 4,000, the pioneering virtual vascular conference continues to attract delegates from far and wide. In this session, presentations, polling, and live discussion enticed nearly 1,000 participants to join live from 75 countries, including the UK, Brazil, USA, Mexico, Italy, Spain, Saudi Arabia, Egypt, Germany, and Argentina—to name the top 10—all keen to ask questions of the experts in the search of consensus on endoleak management. After hearing presentations from leading specialists who recognised that sac expansion is a key indicator for intervention in type II endoleaks, 68% of the CX LIVE audience voted that they regard type II endoleak without sac expansion as harmless.
Roger Greenhalgh (London, UK), chair, was joined by past president of the Vascular Society of Great Britain and Ireland (VSGBI), Ian Loftus (London, UK) as moderator. A significant talking point to emerge from the session was the fact that an expanding sac after endovascular aneurysm repair (EVAR) meant the physician had a job to do—to find the endoleak and put it right. In addition, the audience heard early experience of the use of contrast-enhanced ultrasound, which may help identify persistent endoleak after embolisation.
Questions came in thick and fast from the global CX aortic vascular community, from Kuala Lumpur in Malaysia, to Sao Paulo in Brazil, and Hamburg in Germany, for leading interventional radiologist Lindsay Machan (Vancouver, Canada), who presented on the treatment of type II endoleaks, and surgeon and CX Aortic Executive Board member Gustavo Oderich (Rochester, USA), who highlighted the potential advantage of using contrast-enhanced ultrasound to assess endoleak treatment success intraoperatively.
Machan began by acknowledging the “continuing controversy” over whether type II endoleaks should even be treated, quoting a commentary by Thomas Forbes (Toronto, Canada), published in the Journal of Vascular Surgery in early 2020, in which the author professed to be “struck by how little progress we have made in our understanding of the pathophysiologic mechanism, significance, and treatment of type II endoleak”.
Machan said: “There is currently a lack of agreement on the indications for treatment of type II endoleaks, but an increase in sac size up to, or more than 10mm per year is generally accepted [as reason to intervene]. With specific reference to embolisation as a treatment option, there is no ‘best’ embolic agent, but a patient-specific approach is needed.”
Machan noted that guidelines from both the Society for Vascular Surgery (SVS) and European Society for Vascular Surgery (ESVS) recommend that conservative management is appropriate in isolated endoleaks without sac expansion, but stipulate that with an increasing sac size of 10mm or greater compared to pre-EVAR, treatment should be considered. “A relative indication is expansion of sac size over 5mm over any six-month period,” he said.
The goal of treatment when opting to treat type II endoleaks is access to the nidus, Machan explained, and occlusion of that central communication and the feeding and draining branches. He detailed that there are “multiple” possible access routes, including transarterial, translumbar, perigraft, transgraft, transvenous, as well as laparoscopic and open repairs.
Machan offered examples of each of these approaches but commented that the most commonly used route “still is transarterial embolization”.
Looking at long-term outcomes, Machan highlighted a review from Cleveland Clinic, Cleveland, USA, looking at 140 procedures in 95 patients, with a mean follow-up of just over two years, and using a variety of embolic materials and approaches. The paper, Machan said, described a five-year cumulative survival of 65%, freedom from explant in 89%, and secondary embolisation in 76% of patients. There was, however, sac expansion of more than 5mm seen in nearly half of the patients (44%) at mean two-year follow-up.
Machan’s presentation prompted Greenhalgh to ask during the following panel discussion whether type II endoleak should be considered “unimportant” unless there is sac expansion, and what level of sac increase is important to act upon. Reflecting the lack of clarity over the issue, Machan responded: “I do not pretend to have the answer to those questions. That invited commentary by Thomas Forbes resonated very well with me. We continue in our multidisciplinary rounds to struggle with what to do with type II endoleaks—we use increasing sac size as our primary indication [to intervene].”
An additional question from audience member Ignacio Escotto Sanchez, coming from Mexico City, Mexico, on predictive factors for type II endoleaks potentially converting to type III endoleaks, led Machan to muse on what is seen as another area of challenge in managing endoleaks—imaging. “What we struggle with is a really great method of imaging. We are increasingly using MRA [magnetic resonance angiography], time-resolved images, I would not say that always gives us the answer.”
Contrast-enhanced ultrasound may help identify persistent endoleak after embolisation
This theme was picked up by Oderich, who detailed the use of contrast-enhanced ultrasound for intraoperative assessment and as an effective means of finding the precise location of a type II endoleak. Beginning his presentation, Oderich acknowledged that endoleak diagnosis can be difficult using intraoperative angiography alone. Sharing his views that clearly resonated with the online audience, he noted that although a conservative approach towards type II endoleaks has been recommended, when treatment is indicated, clinical success averages 50 to 60%.
Oderich explained that his centre employs both transarterial and translumbar approaches to treat endoleaks, depending on the type of endoleak and whether the inferior mesenteric artery is patent. The use of intraoperative contrast-enhanced ultrasound is universal, Oderich said, to determine if the endoleak is completely gone, or if there is a persistent endoleak that warrants additional intervention.
Outlining this approach, Oderich detailed a case following fenestrated endovascular aneurysm repair (FEVAR) with type II endoleak from the inferior mesenteric and lumbar arteries. In the example shown to the CX LIVE online audience, a microcatheter was advanced through the inferior mesenteric artery to the aneurysm sac, which was then embolised using a combination of Onyx (Medtronic) and coils. In the supine position, an intraoperative ultrasound with contrast enhancement was then obtained, which showed that although there was some improvement in the endoleak, there was still a persistent type II endoleak from the lumbar arteries. The patient was then turned to the right lateral decubitus position to access the aneurysm sac via a translumbar approach through the abdomen and posterior lower back. “Intraoperative ultrasound is then obtained through the abdomen,” explained Oderich, adding that this was able to demonstrate “complete resolution” of the endoleak.
Oderich shared with the CX 2020 LIVE audience another example of a post-FEVAR patient with significant sac enlargement due to multiple type II endoleaks. In this instance, the aneurysm sac was accessed via the translumbar approach, with Onyx injected mostly towards the left limb of the bifurcated graft. Intraoperative ultrasound was obtained that showed that there was still some residual endoleak posterior to the right limb of the bifurcated graft. “We then created a sac on the needle track from the lumbar approach, aiming for the right limb of the bifurcated graft,” said Oderich. Duplex ultrasound with contrast enhancement was then able to demonstrate complete resolution of the type II endoleak, he said.
The technique has been used in 18 patients to date, Oderich explained. Of these, 11 patients (61%) showed no evidence of residual endoleak. In this subgroup, there were no aneurysm sac enlargements, he added, and only one patient had a small persistent endoleak on follow-up imaging. Seven patients, however, were found to have persistent endoleaks after the first attempt at embolisation. Oderich and colleagues performed a second embolisation in four of these patients and achieved complete resolution in one. Overall, he said, there were six patients with still some small persistent endoleak in this group, while follow-up imaging demonstrated persistent endoleaks in 50%, and two patients still had sac enlargement.
In his concluding remarks, Oderich commented that intraoperative contrast-enhanced ultrasound may help identify persistent endoleak after embolisation, and that additional treatment of persistent endoleak may help minimise the risk of a failed reintervention. However, he surmised that larger clinical experience and longer follow-up is needed to advance the field.
Duplex ultrasound a good alternative to CT
Earlier in the session, Maarit Venermo (Helsinki, Finland) detailed her team’s experience since 2011 with ultrasound surveillance after EVAR. “We have found it feasible,” she told the CX 2020 LIVE audience.
“We can all agree that surveillance after EVAR is necessary,” Venermo began. While “traditionally”, this follow-up has been performed with computed tomography (CT), ultrasound offers a newer alternative that “lowers total radiation burden, is patient-friendly, more cost-effective than CT, and does away with the need for contrast media”, she said.
Venermo and colleagues reviewed consecutive patients who underwent EVAR for intact infrarenal abdominal aortic aneurysm (AAA) between 2000 and 2016. Patients were divided into two groups, depending on whether they followed a CT-based (group A) or ultrasound-based (group B) postoperative imaging protocol. Group A included 168 patients, while B had 301 patients, with patients followed up for an average of 5.6 and 3.6 years, respectively.
The team reviewed case histories and all postoperative imaging studies. “We registered aneurysm sac diameter and possible complications, such as endoleaks, kinking, or stent migration. All interventions were recorded, secondary sac ruptures during follow-up were documented, and reasons leading to the ruptures were discussed .”
The total number of CT scans were 899 and 985 in groups A and B, respectively. “In group A, the number of CTs were 4.3 per patient versus 2.2 per patient in group B. Additional CT due to aneurysm was done in 25% of the patients in group A and 39% in the group B, and one third of the patients in both groups underwent an additional CT for non-aneurysm related reasons,” Venermo explained.
Freedom from reinterventions at one and five years was slightly lower in group A, and a total of 11 aneurysms ruptured during the follow-up: six in group A, and five in group B. Secondary rupture rate per 100 patient years was 0.67 in group A and 0.46 in group B, and cancer as a cause of death was slightly higher in group A, but “the difference was not significant”.
Venermo concluded: “In our study, ultrasound surveillance was not inferior to CT surveillance. The total number of CT scans was lower in group B, even though 40% of patients in the ultrasound surveillance group had additional CT.”
She continued: “Surprisingly, many patients—about a third—underwent CT scans for reasons other than an aneurysm.”
Finally, Venermo added that the data also point to the cost-effective nature of ultrasound surveillance: “Over 10 years, the cost of ultrasound protocol is 57% less expensive than annual CT protocol, despite the single extra CTs conducted on a relatively high proportion of the patients”.
In the discussion, Julian Scott (Leeds, UK) asked whether there were differences in renal function between the ultrasound and CT groups.
Venermo replied: “We actually have an ongoing project where we have studied the renal function of these patients very carefully. In this project, we did not have these values, but in the near future I can tell you the answer.”
Loftus then asked a question on whether follow-up protocols should differ for EVAR patients who were not treated within the instructions for use (IFU).
“I am not sure if our protocol is perfect,” Venermo admitted, who went on to suggest potentially different surveillance protocols might be the answer for EVAR patients treated within the IFU from those treated outside it.
Vascular technologists key to delivering ultrasound
With the data pointing to ultrasound surveillance following EVAR fast becoming a feasible option, the provision of vascular ultrasound services was also on the CX 2020 LIVE agenda.
Lee Smith (Bolton, UK), Society for Vascular Technology of Great Britain and Ireland (SVT) president, stressed the vital role of the SVT in “setting standards and ensuring its members achieve and maintain these standards, along with promoting research and development”. He emphasised the vital role of the vascular scientist in the management of ultrasound, detailing that it is a “dynamic and highly user-dependent imaging modality”, and as such “should only be used for diagnosis by a suitably trained professional”.
Majority of global CX 2020 LIVE audience happy with final NICE aortic guidelines
Michael Jenkins (London, UK) and Loftus formed part of the VSGBI 2019 membership committee that influenced the UK National Institute for Health and Care Excellence (NICE) guidelines such that the final published document allows funding for EVAR under select circumstances.
In March, the long-awaited NICE guidelines on AAA diagnosis and management were published. While the guidelines are in favour of open repair for most patients, they also highlight circumstances in which open repair is contraindicated because of structural or anaesthetic medical comorbidities.
Greenhalgh offered his congratulations to Loftus, noting that he played a “major role” in ensuring the wording of the final recommendations during his term as VSGBI president. When asked “Are you happy with the final NICE aortic guidelines?” 61% of the global CX 2020 LIVE audience replied in the affirmative.