An off-the-shelf endograft for the treatment of thoracoabdominal aortic aneurysms (TAAA) provides a safe and straightforward solution for a wide range of patients—including emergency cases. Data for the Zenith T-branch endograft were presented by Martin Austermann (Münster, Germany) at the 2019 Charing Cross Symposium (CX; 15–18 April, London, UK).
Contextualising this study, Austermann explained to the audience that “Open repair of thoracoabdominal aneurysms is, even in high-volume centres, still associated with significant mortality and morbidity. Using an endovascular approach could reduce mortality and morbidity by avoiding cross-clamping and reimplantation of the renovisceral vessels.”
Indeed, endovascular repair is increasingly used to treat patients with TAAA, but manufacturing customised stents can take up to eight weeks, limiting its use in urgent cases. Austermann told CX delegates that although custom-made fenestrated and branched endovascular aneurysm repair (EVAR) devices had been well established for the last 15 years, the waiting time for the custom made devices “excludes a remarkable number of patients with very big, ruptured or symptomatic aneurysms”.
The Zenith T-branch endograft was launched by Cook Medical in September 2012 as an immediate solution for patients with any type of TAAA. The endograft has four downward facing cuffs for the renal and visceral arteries, and can be further extended at the proximal end with tapered off-the-shelf components, enabling interventionists to accommodate individual patient anatomies. A distal, bifurcated graft is available in four lengths. Previous studies have suggested that it is suitable for around half of patients otherwise treated with custom-made endografts.
The presentation gave the short-term results of this post-market, multicentre, observational study evaluating the use of the T-branch endograft in routine clinical care. Eighty patients from two sites in Germany and one in Sweden were enrolled in the study between September 2012 and November 2017, with 96% of them treated for aneurysms, and 4% of them for dissections. Half of the procedures were performed in a staged fashion. The primary outcome was procedure-related mortality and morbidity at 30 days. Secondary outcomes included longer-term mortality and morbidity, patency of the graft and bridging stents, device integrity, and aneurysm growth.
The technical success rate was 100%. There was one death within 30 days, and there were no ruptures or conversions to open repair.
Elaborating on these positive, preliminary results, Austermann said this was particularly notable as the patient population was “very ill”. Most of the patients (38%; 29/77) treated for aneurysms (so most of the patients enrolled in the study) were Type II on the Crawford classification. Thirty-four per cent (26/77) were designated Type IV, and a further 18% (14/77) were designated Type III, with the remaining 7% (5/77) a Type I. Therefore, the majority of patients had “very extensive disease”. Austermann also emphasised the fact that 25% (20 patients) were symptomatic or contained ruptures, and 30% had a renal impairment or a severe cardiac disease. Given the added complications of treating “such a sick patient group”, Austermann highlighted that treating all patients through endovascular means, even when secondary interventions were necessary, was “impressive”.
After one-year follow-up, the freedom from all-cause mortality was above 90%; freedom from secondary interventions at one year was close to 87.7%. Austermann stressed that “most of the patients [92.3%; 24/26 patients] showed a decrease in aneurysm size of more than 5mm [at one year]; most of the rest [7.7%; 2/26 patients] had no changes in size, and there was no increase in this group of patients”.
The T-Branch design leads to a broad applicability, including urgent cases, Austermann said. “Planning the procedure is easy, and implantation is very safe and straightforward. In emergency cases, the use of T-branch saves lives,” he added. Detailing the “obvious” advantages of the Zenith T-branch endograft, Austermann elaborated: “We have no waiting time, and the applicability is very good. About two-thirds of our patients [63%] can be treated with this device, shown by Timothy Chuter’s group [Nottingham,
UK] and also our group. The planning is relatively easy; you have to locate the target vessels, and it should match the pattern of the T-branch—then you can use it.
“The implantation is very safe and stress free—you can do everything stepby- step. It is also a very forgiving device, because implantation as well as planning does not have to be too exact. The only mistake you can make is to place your endograft too low, as then you can run into problems.”
During implantation, the interventionist gains access both through the groin and through the left axillary artery. When questioned on this approach, Austermann said: “In our centre, we always come from the left axillary artery, but I know others sometimes go from the right side. I just much prefer the left side.” On gaining access to the vasculature, the physician places the graft and closes the access site in the groin. “We then have all the time we need,” Austermann said, “to connect and attach all the target vessels to the cuffs.” Austermann explained that, in his experience, this minimises the risk for spinal cord ischaemia.
Spinal cord ischaemia was also the topic of discussion following Austermann’s presentation. The short-term results included a 12% neurologic event rate, encompassing strokes and spinal cord ischaemia. Responding to a query concerning the use of a spinal drain, Austermann said that he had reviewed his own data from 2014 and 2015, and observed a 5% complication rate following EVAR, which he attributed largely to spinal cord drainage: “When comparing between those who had spinal cord drainage and those who did not, we saw a significant difference in complication rate.” He therefore decided in 2015 to only perform spinal cord drainage post-operatively, when necessary, reporting a more recent complication rate of 2%: “So we have lowered this [complication rate],” he stated.
An additional questioner also remarked on the three strokes reported in this patient population, and asked Austermann if he had noticed any difference in the rate of strokes between patients with left or right brachial access. However, Austermann did not report finding any association between access direction and stroke rate. He also added that these strokes were “all minor”, and acknowledged that this is “a potential issue”.