Understanding the Interaction Between Transcatheter Aortic Valve Prostheses and Supra-Annular Structures From...

The authors sought to better understand the stent geometry of the Lotus valve after transcatheter aortic valve replacement (TAVR) and its potential implications for valve size selection.

The authors hypothesized that the greatest interference between the frame and aortic valvar complex occurs across the aortic valve leaflets.

The authors retrospectively analyzed the multidetector computed tomography (MDCT) scans of 32 consecutive patients undergoing Lotus valve (Boston Scientific, Natick, Massachusetts) implantation. The prosthesis cross section was analyzed at 3-mm increments along its length. The plane where the frame had the smallest area was defined as the waist. The corresponding plane of the waist on pre-procedural MDCT was identified by surrounding structures such as calcium deposits, commissural fusion, and commissural gaps, and was referred to as the supra-annulus. The spline of the supra-annulus was circumscribed with reference to the post-implant stent geometry at the waist.

The waist was 5.8 ± 1.7 mm higher than the native annulus on post-procedural MDCT. The waist had a nearly 2-fold larger compression rate than the stent at the native annulus level (36.3 ± 10.4% vs. 18.9 ± 9.6%; p < 0.01), irrespective of valve morphologies. The supra-annulus was 5.9 ± 1.6 mm higher than the annulus on pre-procedural MDCT. Patients had an approximately 17% decrease in area from the annulus to the supra-annulus (18.3 ± 4.4% for bicuspid morphology and 16.0 ± 3.5% for tricuspid morphology).

Major interference between the implanted prosthesis and anatomy occurred at a level above the annulus. The decrease in area from the annulus to supra-annulus may explain the feasibility of implanting a smaller valve than that suggested by traditional annular measurements.