Abstract 2285: Transcatheter Mitral Valve Replacement
Background. We recently reported successful off-pump transapical mitral valved stent implantation in an acute experimental setting. The current study was designed to assess short term survival after transcatheter mitral valve replacement using a similar approach.
Material and Methods. A self-expanding, repositionable mitral valved stent was designed as a main stent body housing a trileaflet glutaraldehyde-preserved porcine valve provided with atrial and ventricular fixation systems. Eight pigs underwent transapical mitral valved stent implantation through a lower mini-sternotomy. After the function of the newly implanted valved stent was assessed by transesophageal echocardiogram (TEE) and left ventriculogram, animals had their incision closed and allowed to recover from anaesthesia.
Results. The mean mitral annulus size was 24.6±1.4 mm and the valved stent size was 26.0±2.6 mm. The average mean transvalvular gradient across the valved stent and mean gradient across the left ventricular outflow tract (LVOT) recorded immediately after deployment, after 6 hours and after one week were 1.8±1.0 mm Hg, 3.4±1.7 mm Hg, 4.2±2.3 mm Hg and 1.3±1.3 mm Hg, 1.4±0.7 mm Hg, 1.9±0.6 mm Hg, respectively. Animals survived between 8 hours and 29 days. All but one animal that died before one week (early group, n=4) had mild paravalvular regurgitation immediately after valved stent implantation documented by color flow Doppler. Death in this early group was a consequence of unrecognized suboptimal valved stent positioning. The later group had precise deployment with only trace paravalvular leak and survived one week or more. The causes of death in this latter group were endocarditis (n=1), failure of atrial fixation (n=2) and failure of ventricular fixation (n=1). There was no stent migration nor stent fractures in the main stent body seen with this valved stent.
Conclusion. The new mitral valved stent can be deployed in a reproducible manner to achieve reliable stent stability, minimal gradients across the LVOT and adequate valved stent function. This study is the first to report survival after transcatheter mitral valve replacement. Further refinements in the stent design are tested to allow improved durability.