Abstract Body (Do not enter title and authors here): Background: With the increasing prevalence of transcatheter mitral valve-in-valve interventions (V-in-V), a detailed understanding of the surgical valves (SV) is of paramount importance. Left ventricular outflow tract obstruction (LVOTO) is a feared complication and is typically caused by the anterior displacement of the LVOT-facing surgical leaflet, which, along with the surgical post at that level, forms a fixed obstruction. Traditionally, the risk is estimated using computed tomography software by simulating a valve that extends to the surgical post height of the implanted SV. However, this does not account for the actual leaflet length and post width at the level of the leaflet tip, which could differ significantly from the surgical post height but accurately estimate LVOTO risk.

Methods: We conducted detailed measurements of three different sizes of two commonly used surgical mitral valves: the Biocor EPIC (Abbott) in sizes 27 mm, 31 mm, and 33 mm, and the Mosaic (Medtronic) in sizes 25 mm, 31 mm, and 33 mm. Using a digital caliper and height gauge, we measured several key parameters for each valve, including leaflet height, post height, leaflet width, post width at the level of the leaflet tip, maximal post width, and valve inner diameter.

Results: The results, presented in Table 1, show significant differences in leaflet height and post widths across manufacturers and sizes. Leaflet height was consistently shorter than post height in both Abbott and Medtronic valves, with this discrepancy more pronounced in larger valves and Medtronic valves. The post width at the leaflet tip also varied considerably.

Conclusions: Given the substantial differences between leaflet and post heights—with the leaflet typically much shorter—an accurate assessment of LVOTO risk should account for both the leaflet height and the width of the post at that level to avoid overestimating the risk of LVOTO.