In the first study of its kind, scientists have conducted a computed tomography (CT) analysis of the in vivo frame geometry of the Navitor intra-annular self-expanding valve (SEV). Designed by Abbott Structural Heart, the valve is said to advance transcatheter aortic valve replacement (TAVR) technology, notably in commissural alignment and improved patient outcomes. “While it is straightforward to perform CT simulation with balloon-expandable valves, simulation with SEV is more challenging,” said the authors of the research letter published in JACC: Cardiovascular Interventions on Monday. “Our study therefore suggests that the native annular dimensions may be used to model the index Navitor TAV on CT to predict redo TAVR feasibility.” Key findings Key findings from the research, led by Dr Gilbert H.L. Tang, MD, from Mount Sinai Health System in New York, revealed the Navitor demonstrated unique geometric behavior, despite being a SEV. While initial inflow dimensions were less circular, the valve frame became increasingly circular toward the commissural level. According to the team, this feature enhanced the valve's compatibility with native annular dimensions — an important factor for reducing paravalvular leaks (PVL). Other findings revealed the valve’s in vivo expansion index, which ranged from 60-80% of its labeled size, that emphasized the importance of accurate pre-implantation planning. Notably, the study’s authors emphasized that due to this range, labeled sizes could not be solely relied upon for planning redo-TAVR procedures. The Navitor Vision achieved a commissural alignment in 38.7% of patients. This was considered promising when in comparison to cited studies that suggested a better circularity at the commissural level achieved by Navitor and an improved performance over time. "Frame eccentricities approximated those of the native annulus across TAV sizes and became more circular at the commissural level,” the authors highlighted. Low complication rate The research team also noted a low complication rate in which a thirty-day follow-up revealed a favorable safety profile, with a mortality rate of 0.9%, two strokes, and one major vascular complication. The pacemaker implantation rate was 9.4%, and 92.4% of patients exhibited none or trivial PVL. However, 16% of cases reported hypoattenuated leaflet thickening, an observation linked to valve design and expansion. Commenting on the study’s unique nature, the authors noted a similarity in the eccentricities of other SEVs, such as Medtronic’s Evolut and Boston Scientific’s ACURATE valves. However, the Navitor’s superior circularity at the commissural level over these valves suggested a potential edge in long-term valve function. As evidence of further innovation, the researchers highlighted the Navitor’s commissural markers that they said helped deployment precision and reduced risks during TAVR procedures. Future considerations The study highlighted a number of implications for future TAVR and redo-TAVR procedures, particularly as younger and lower-risk patients become suitable for such interventions. Specifically, accurate pre-TAVR CT simulation would becoming increasingly critical for predicting the feasibility of redo-TAVR, given that in vivo dimensions often deviated from simulations. The authors said modeling the index Navitor valve using native annular dimensions was preferable over labeled sizes to ensure successful redo-TAVR outcomes. Research methodology The study analyzed data from 106 patients that evaluated the latest version of the Navitor intra-annular self-expanding valve (SEV): Navitor Vision. Employing multidetector CT imaging, the team homed in on the valve’s geometry at different levels, from its inflow to its commissural regions. Specific points of assessment include the valve’s eccentricity, expansion index and alignment post-implantation, as well as critical parameters that confirm the valve’s long-term efficacy. Imagers measured the Navitor’s dimensions and evaluated its ability to achieve full circularity, a desirable feature for optimal blood flow. Clinical outcomes were noted at discharge and after 30 days. Source: Tang G, Kobari Y, Vinayak M, et al. In Vivo Frame Geometry of the Navitor Intra-Annular Self-Expanding Valve: A First-in-Human CT Analysis. JACC Cardiovasc. Interv. 2024 (Article in Press). Image Credit: Abbott Cardiovascular – cardiovascular.abbott.com