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

Area of Science:

• Cardiovascular Surgery
• Biomedical Engineering
• Interventional Cardiology

Background:

• Transcatheter mitral valve replacement (TMVR) is an evolving procedure for mitral valve disease.
• Fixation strategies significantly impact device performance and patient outcomes.
• Neo-left ventricular outflow tract (neo-LVOT) obstruction is a critical postoperative complication.

Purpose of the Study:

• To compare the effects of two TMVR fixation strategies on neo-LVOT dimensions and aorto-mitral angulation (AMA).
• To evaluate the potential of different fixation methods to mitigate neo-LVOT obstruction.

Main Methods:

• Development of two transapical TMVR prototypes using self-expanding nitinol valved stents.
• Comparison between an annular fixation system (ANN group, n=6) and an apical tether fixation system (AP group, n=11).
• Echocardiographic assessment of AMA and neo-LVOT dimensions pre- and post-implantation.

Main Results:

• The apical fixation (AP) group demonstrated significantly narrower maximal and minimal AMA compared to the annular fixation (ANN) group (p<0.001 and p=0.009, respectively).
• The ANN group experienced a more severe reduction in neo-LVOT diameter (60±11% vs 26±14%, p<0.001).
• Higher peak velocities were observed in the neo-LVOT post-implantation in the ANN group (200±52 cm/s vs 108±15 cm/s, p<0.001).

Conclusions:

• Apical fixation TMVR maintains a more stable and smaller AMA.
• Apical fixation preserves a larger neo-LVOT, reducing the risk of obstruction.
• This experimental study suggests apical fixation as a promising strategy for safer TMVR.