Understanding the mechanisms behind the annuloplasty effect in tricuspid valve TEER: a computational study

An annuloplasty effect has been observed following tricuspid transcatheter edge-to-edge repair (TEER) and is associated with a therapeutic benefit. However, the mechanisms underlying the annuloplasty effect remain unknown. In this study, we investigated the impact of TEER-induced annular forces on the annuloplasty effect. Additionally, we explored the influence of clip size, clip orientation, leaflet pair, and leaflet site on TEER-induced annular forces. To this end, we simulated 34 TEER repairs in finite element models of three human tricuspid valves. We used an NTW or XTW TriClip, placed between either the anterior-septal or anterior-posterior leaflet pairs at a central or near-annulus site. For each scenario, we quantified the reduction in annular area, septal-lateral (SL) diameter, and anterior-posterior (AP) diameter. We also reported the total annular force, orientation of maximum annular force, total papillary muscle force, leaflet stress, and coaptation area ratio following TEER. We found that TEER induced annular forces (2.00 ± 1.68 N), which were associated with the annuloplasty effect as measured by reduction in annular area (3.11±2.29%, p < 0.0001) and SL diameter (2.10±2.25%, p < 0.0001). The maximum annular force aligned with the orientation of the clip (p < 0.0001). Furthermore, larger XTW clips induced more annular force (p < 0.0001) and leaflet stress (p < 0.0001) than smaller NTW clips. A central anterior-posterior site induced more force than a near-annulus anterior-posterior site (p = 0.0166), but showed no difference from an anterior-septal pair (p = 0.939). In summary, we demonstrated that TEER procedural parameters alter the magnitude of induced annular forces, which, in turn, correlate with the degree of annuloplasty effect.