Tricuspid valve geometry and right heart remodelling: insights into the mechanism of atrial functional tricuspid regurgitation.

Aims: We sought to investigate tricuspid valve (TV) geometry and right heart remodelling in atrial functional tricuspid regurgitation (AF-TR) as compared with ventricular functional TR with sinus rhythm (VF-TR).
Methods and Results: Transoesophageal 3D echocardiography datasets of the TV and right ventricle were acquired in 51 symptomatic patients with severe TR (AF-TR, n = 23; VF-TR, n = 28). Three-dimensional right ventricular (RV) endocardial surfaces were reconstructed throughout the cardiac cycle and then postprocessed using semiautomated integration and segmentation software to calculate position of papillary muscle (PM) tips. Compared with VF-TR, AF-TR had more dilated and posteriorly displaced annulus and less leaflet tethering angles with more prominent right atrium and smaller RV end-systolic volume. On the XY (annular) plane, the centre of annulus was getting closer towards the anterior and posterior PM tips and was going away from the medial PM tip caused by prominent annular dilatation in AF-TR. On the Z-axis, the position of each PM tip in AF-TR was not so much displaced apically as that in VF-TR. Multiple linear regression analyses revealed that right atrial volume and right atrial/RV end-systolic volume ratio were determinants of annular area and orientation in AF-TR, respectively (both P < 0.001). Additionally, the posteromedial-directed component of posterior PM tip position and the apically directed component of the position of all three PM tips were independently associated with TV tethering angles of each leaflet in AF-TR (all P < 0.02).
Conclusion: Right heart remodelling and its association with 3D TV geometry differ entirely between AF-TR and VF-TR, which may offer distinctive therapeutic implication.
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