The four-branch Gore Excluder thoracoabdominal branch endoprosthesis (TAMBE) device demonstrated low mortality at one year with renal artery occlusion being the predominant device-related event associated with small renal arteries and pararenal aneurysms. So concluded Mark A. Farber, MD, presenting the latest TAMBE data during yesterday’s William J. von Liebig Forum.
Drawing a take-home message from the new findings—which were simultaneously published online in the Journal of Vascular Surgery (JVS)— Farber advised: “During follow-up, attention should be focused on renal branch assessment to identify patients at risk for occlusion.”
The chief of the Division of Vascular Surgery and professor of surgery at the University of North Carolina at Chapel Hill was presenting one-year results from the pivotal trial of the Gore TAMBE to treat extent IV thoracoabdominal aortic aneurysms (TAAAs) and pararenal aortic aneurysms (PRAAs). Farber detailed that this prospective, non-randomized, multicenter study included 102 patients, 59 of whom had an extent IV TAAA and 43, a PRAA, adding that the mean maximum aneurysm diameter was 59.4mm.
The presenter shared that, at one year, eight patients were lost to follow-up and six patients died, specifying that one death was device-related, one was procedure-related, and four were due to unrelated causes. He stated that, in total, 88 patients completed a follow-up visit at one year.
Moving on to key results, Farber revealed that freedom from all-cause mortality at one year was 94.1% and that target vessel occlusions occurred in 14.7% of patients. This figure included one celiac artery, one superior mesenteric artery (SMA), eight right renal and six left renal artery occlusions.
Farber continued that reintervention was attempted in six of the renal arteries and involved additional target vessel stenting in three patients, thrombolysis and embolectomy in two, and angioplasty in one. “Although branch vessel occlusion events were more common in pararenal aneurysms compared to extent IV TAAAs, this was not significant,” he said.
Looking at renal patency, Farber reported that renal artery patency was influenced by renal artery diameter, with renal arteries of less than 5mm in diameter being three times more likely to occlude. He also noted that acute kidney injury requiring dialysis occurred in 1.96% of patients and that renal deterioration— defined as a greater than 25% decrease in glomerular filtration rate (GFR) over two consecutive visits—was 18.9% through one year. Additionally, Farber revealed that renal artery primary patency at one year was 91.8% and “nearly identical between the right and left renal arteries.” Primary patency with respect to renal arteries greater than 5mm in diameter, he continued, was 95.1%, while for those less than 5mm it was 82.5%.
Farber shared that 94.2% of target vessels were free from target vessel instability events through one year. At the individual vessel level, he noted that Kaplan-Meier estimates for freedom from target vessel instability were 99%, 97.1%, 90.8% and 89.8% for the celiac, SMA, right renal and left renal arteries, respectively.
Furthermore, Farber outlined device effectiveness data at one year, which included no major endoleaks, aortic enlargement in 5.4% of patients, and loss of device integrity in 16.3%, which he specified included wire fractures in 3.6% and compression in 12.2%. Farber reiterated that renal deterioration was seen in 18.9%, and that reintervention occurred in 15.6%.
“With respect to the reinterventions,” Farber outlined, “approximately one-quarter were major and included thrombectomy or thrombolysis in five, [and] one exploratory laparotomy for aortic bifurcation rupture to control bleeding.”
Minor reinterventions, the presenter continued, included treatment of target vessel stenosis in eight patients, target vessel occlusion in two and branch-related endoleak treatment in three.
Revealing overall device performance data, Farber shared that combined device effectiveness was achieved in 60.5% and 78.7% of the pararenal and type 4 TAAAs, respectively. “This difference was mainly driven by a higher incidence of target lesion growth and branch vessel occlusion in pararenal aortic aneurysms,” the presenter commented.
In the discussion following Farber’s presentation, Wes Moore, MD, of David Geffen School of Medicine at UCLA in Los Angeles, asked how the new data might weigh up to those for physician-modified endovascular grafts (PMEGs).
“It’s hard to compare those results because we’re talking about a four-branch off-the-shelf device, and the majority of the PMEGs are probably fenestrations or laser fenestrations depending upon where you are, and so it’s hard to compare those,” Farber responded. “The important part about the manuscript is that we know that there are renal events that occur and that the goal of this manuscript is to talk about how you can help select your patients better. We have some renal events and 95% patency if you’re greater than 5mm at a year. If you have a patient who has small renal arteries, you need to think about how this might impact them since renal function is linked to survival.”
A subsequent question from Dawn Coleman, MD, of Duke University in Durham, North Carolina, homed in on the reliability of the device in question. “I was struck by the data around the loss of integrity of 16% at one year,” she remarked. “That’s a striking number.” Coleman went on to ask Farber how he would interpret this figure, and whether he has any insights on which patients were at most risk.
Farber first addressed the 3.6% rate of wire fractures. “Where they have the constraining sleeve, Gore identified a manufacturing issue which was corrected during the study, so that number should go down and we’ll have to look at that in the future because this issue involves both primary and secondary arm patients,” Farber commented.
Moving on to address the 12.2% rate of device compression, he detailed that the trial saw 11 compressions in total, including nine in the branch vessels. “Of those, about half of them had an occlusion and were reintervened upon such that at one year, seven of the nine compressions were patent.”
Farber advised conducting a “3D spin” at the end of a procedure to look for compressions and “fix those problems as they occur.”
