A preliminary analysis of late structural failures of the Navion stent graft in the treatment of descending thoracic aortic aneurysms

Abstract

Objective: Patients in the Valiant Evo U.S. and international clinical trials had positive short-term outcomes; however, late structural failures, including type IIIb endoleaks have been recently discovered. Type IIIb endoleaks are serious adverse events because the repressurization of the aneurysm sac increases the risk of rupture. The purpose of the present study was to detail the imaging patterns associated with the structural failures with the aim of increasing awareness of failing graft presentation, early recognition, and prompt treatment.Methods: The Valiant Evo clinical trial was a prospective, single-arm investigation of a thoracic stent graft system. With the recent late structural failures, sites were requested to submit all available imaging studies to date to allow the core laboratory to assess for structural failures such as type IIIb endoleaks, stent ring fractures, and stent ring enlargement. Of the 100 patients originally enrolled in the trial from 2016 to 2018, the core laboratory assessed the imaging studies performed at $1 year for 83 patients.Results: No structural failures of the graft were reported through 1 year of follow-up. At 1 to 4 years, graft structural failures were detected in 11 patients with descending thoracic aortic aneurysms. Of the 11 patients, 5 had a type IIIb endoleak. Four of the five had imaging findings showing stent fractures consistent with the location of the graft seam and one had a type IIIb endoleak attributed to calcium erosion with no stent fracture or ring enlargement. Of the four patients with stent fracture in line with the graft seam, three underwent a relining procedure that successfully excluded the type IIIb endoleak. One of these three patients died 4 days later of suspected thoracic aortic rupture because the distal thoracic endovascular aortic repair extension had been landed in a previously dissected and fragile section of the aorta. The remaining six patients had had stent ring enlargement. One of the six patients had had persistent aneurysm expansion from the time of implantation onward and had died of unknown causes. The remaining five patients have continued to be monitored. Conclusions:In the present preliminary analysis, the imaging patterns associated with type IIIb endoleaks, stent fractures, and stent ring enlargement appear to be related to the loss of seam integrity or detachment of the stent rings from the surface of the graft material. The imaging patterns we have detailed should be closely monitored using computed tomography angiography surveillance to allow structural failures to be promptly identified and treated.

Early Clinical Outcomes of Initial Launch of the Zenith Alpha Abdominal Endovascular Graft in Japan

“…14,15 While there are benefits to reducing the profile, it may lead to a loss of overall performance and durability of the device. [4][5][6][7][8] Zenith Alpha AAA is a new-generation low-profile endovascular graft that is already available in Europe, Australia, Canada, and Brazil; however, reports on the clinical results are currently lacking in the literature with only 1 study reporting 30 days clinical result. 11 In this report, we retrospectively evaluated consecutive 79 patients in the initial launch of Zenith Alpha AAA in Japan, and found that sac shrinkage of >5 mm was achieved in 42.2% of patients, with satisfactory freedom from late complication rate of 90.8% at 12 months.…”

“…Durable repair has become a considerable topic in the EVAR procedure and is also the biggest concern with lowprofile endovascular graft. [4][5][6][7][8] The conventional Zenith endovascular graft, which is one of the longest selling EVAR devices on the market, has been reported to have good long-term results. 9,10 One of the strengths of conventional Zenith endovascular grafts is the greater early sac shrinkage observed compared with other devices.…”

“…The other major concern with low-profile endovascular grafts is limb occlusion. [4][5][6][7] Limb occlusion is an important complication following EVAR, with a reported incidence ranging from 2.6% to 7.4%. [20][21][22] Many factors affect the incidence of limb occlusion following EVAR.…”

“…However, durability has become a major concern in low-profile devices. [4][5][6][7][8] A new-generation low-profile endovascular graft, Zenith Alpha Abdominal Endovascular graft (Zenith Alpha AAA), which has a 16-17 Fr delivery system, was introduced partially in Japan in March 2019, starting with 9 selected sites (Figure 1). Multiple studies have reported the long-term data of the original Zenith AAA endovascular graft (Zenith AAA, Cook, Inc, Bloomington, Indiana) 9,10 ; however, the clinical outcomes of Zenith Alpha AAA are currently lacking in the literature with only 1 study reporting 30 days outcome.…”

Thoracic endovascular aortic repair: Current evidence and challenges

“…Patients treated with the Val- A total of 50 patients who suffered a blunt aortic trauma were enrolled in a study to assess the Zenith Alpha thoracic endovascular graft (Cook Medical, Bloomington, IN, US, Figure 4). During a mean 21-month follow-up, a 30% incidence of in-graft thrombus resulted in the manufacturer's voluntary removal of the blunt-aortic-trauma indication for this device [23].…”