Transcatheter mitral valve replacement (TMVR): annular or apical fixation?

Aims: The aim of this study was to evaluate the impact of two different transcatheter mitral valve replacement (TMVR) fixation strategies on the neo left ventricular outflow tract (neo-LVOT) and aorto-mitral angulation (AMA) after TMVR.

Methods and results: Two different self-expanding nitinol valved stents were developed for transapical TMVR. In one group, the stents were fixed with an annular fixation system (ANN group, n=6). These prototypes were compared with an apical tether fixation TMVR system (AP group, n=11) in another group. Echocardiographic evaluation of the AMA and the neo-LVOT was conducted before and one hour after implantation. Maximal and minimal AMA (AMA_max and AMA_min) during the cardiac cycle of the AP group were significantly narrower than those of the ANN group (AMA_max: 39±8° vs 67±15°, p<0.001, AMA_min: 33±10° vs 56±22°, p=0.009). More severe reduction of the neo-LVOT diameter was observed in the ANN group (60±11% vs 26±14%, p<0.001). The ANN group had a higher peak velocity through the neo-LVOT post implantation (200±52 cm/s vs 108±15 cm/s, p<0.001).

Conclusions: The apical fixation system maintains a smaller and more stable aorto-mitral angulation and a larger neo-LVOT, thereby reducing the risk of postoperative neo-LVOT obstruction in this experimental setting.