LAUSR

OBJECTIVES Patients in the Valiant EVO US and International Clinical Trials had positive short-term outcomes, but late structural failures including Type IIIB endoleaks have been recently discovered. Type IIIB endoleaks are serious adverse events as the re-pressurization of the aneurysm sac increases the risk for rupture. The purpose of this report is to detail the imaging patterns associated with the structural failures with the aim of increasing awareness on failing graft presentation, early recognition, and prompt treatment. METHODS The Valiant EVO clinical trial is 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 to date so the core lab could 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 lab assessed imaging at one-year or later from a total of 83 patients. RESULTS There were no structural failures of the graft reported through one year. Between one and four years, graft structural failures were detected in eleven patients with DTAAs. Five of the eleven patients had a Type IIIB endoleak. Four of those five patients had imaging showing stent fractures consistent with the location of the graft seam, while one of the five had a Type IIIB endoleak attributed to calcium erosion with no stent fractures or ring enlargement. Of the four patients with stent fracture in line with the graft seam, three patient had relining procedures that successfully excluded their Type IIIB endoleaks. One of the three relined patients died four days later from suspected thoracic aortic rupture as the distal thoracic endovascular aortic repair (TEVAR) extension was landed in a previously dissected and fragile section of the aorta. The remaining six patients were identified with stent ring enlargement. One of the six patients had persistent aneurysm expansion from the time of implant and died of unknown causes. Five of the six patients continue to be monitored. CONCLUSIONS In this preliminary analysis, imaging patterns associated with the Type IIIB endoleaks, stent fractures, and stent ring enlargements appear to be related to loss of seam integrity or detachment of the stent rings from the surface of the graft material. The imaging patterns detailed here should be closely monitored with computed tomography angiography surveillance so structural failures can be promptly identified and treated.