Clinical Trial Outcomes and Thoracic Aorta Morphometry after One Year with the Valiant Navion Stent Graft System.

Abstract Authors' Note: On February 17, 2021, Medtronic Inc issued a global voluntary recall of the Valiant NavionTM Thoracic Stent Graft System (the device being studied in the Valiant Evo Global Clinical Program that is the subject of this publication), and instructed physicians to immediately cease use of the Valiant Navion system and return any unused product. Medtronic initiated the recall in response to three clinical trial subjects being recently observed with stent fractures, two of which have confirmed type IIIb endoleaks. The data collection, analysis, and manuscript submission occurred prior to the notice of this recall and specifically, the 100 procedures reviewed for this series were free of events at 1 year related to the reason for this device recall. The authors of this article and the manufacturer were unaware of the recently detected adverse events at the time of the preparation of the manuscript and 1-year trial results, and imaging-based analyses described herein are unchanged. Management of thoracic aortic aneurysms remains to be a challenging problem and outcomes are dependent on patient anatomy. The publication focuses on the importance of achieving proximal and distal seal as well as consideration of the temporal changes of the aortic morphology as part of the TEVAR planning process. The authors feel there is still scientific merit in disclosing this information, despite the current non-availability of the Valiant Navion system Objectives The Valiant Navion stent graft system (Medtronic Inc, Santa Rosa, CA) is a third-generation device with improved conformability. One-year clinical trial outcomes are reported along with a focus on an imaging-based analysis of aortic morphology. Specifically, the authors assess the effect of graft implantation on the native anatomy and vice versa how one-year changes in thoracic aorta morphology can affect the original seal zones of the stent graft. Methods A total of 100 subjects were enrolled in the prospective single-arm clinical trial investigating the Valiant Navion stent graft system. An independent Core Lab (Syntactx, New York, NY) assessed anatomical characteristics and performance outcomes. Results Through one year, the freedom from all-cause mortality, aneurysm related mortality, and secondary procedures was 89.8%, 97.0%, and 94.8% respectively. There were five subjects that received a total of six secondary procedures and there were nine subjects with endoleaks (Type IA and Ib (1), Type IA (1), Type IB (3), Type II (4)) within the first year. After one year, 2.6% (2/76) of the patients had an increase in their maximum aneurysm diameter of 5mm or more, 81.6% (62/76) had stable sacs, and 15.8% (12/76) had sac shrinkage. While there were no deployment failures, 36% (36/100) of the proximal and 31% (31/100) of the distal attachment zones were considered short based on author definitions. The stent graft conformed to the native anatomy at implant as the pre-procedural thoracic aorta tortuosity (1.45±.02) was not significantly changed one-month post-implant (1.46±.02). Despite a natural increase in thoracic tortuosity after one year (1.49±.02), wall apposition was maintained over time as evidenced by the low endoleak rates. Aortic elongation and dilation occurred at the proximal end of the graft on average by 1.2mm and 1.6mm, respectively. The aortic remodeling was more pronounced at the distal end with an average increase of 4.2mm in length and 2.8mm in diameter. Conclusions Subjects had positive one-year outcomes with high freedom from mortality, endoleaks, and secondary procedures. Aortic elongation and dilation were more prevalent at the distal end which emphasizes the importance of distal attachment zone consideration as part of pre-case planning. As aortic remodeling is expected to continue over time, additional follow up and imaging analysis in the trial is necessary to assess aortic morphology and its effects on stent graft performance.