Morphologic differences in atrial and ventricular secondary tricuspid regurgitation by computed tomography

Abstract Background Differences in the mechanism behind atrial (ASTR) and ventricular (VSTR) secondary tricuspid regurgitation cause distinct remodeling in the tricuspid valve annulus (TA), right atrium (RA) and right ventricle (RV). Although these morphological changes have been described by echocardiography, computed tomography (CT) can provide better spatial resolution and detailed anatomical information particularly when planning valvular interventions. Purpose To compare the morphologic characteristics of the TA, RA and RV between ASTR and VSTR as measured by CT. Methods Patients with at least moderate secondary TR and who underwent CT were selected as follows: for the ASTR group (n=32), patients referred for atrial fibrillation (AF) ablation; for the VSTR group, patients referred for transcatheter aortic valve implantation, and which were further subdivided according to the presence of AF (with AF [n=51] and without AF [n=68]). Multiparametric echocardiographic approach was used to define TR severity. CT dataset were analyzed in diastole using a dedicated software for the following parameters: TA area, perimeter, antero-posterior (AP) and septal-lateral (SL) diameters, eccentricity index, annulus depth (to assess TA saddle shape), and RA and RV dimensions and volumes (Fig. 1). Results TR was more severe in VSTR, as 55% and 43% of patients had severe to massive TR in the VSTR group with and without AF, respectively, as compared to 12% in the ASTR group (p<0.001). The TA area was significantly larger in the ASTR and VSTR with AF patients (Fig.2), with a trend towards a more circular annulus by eccentricity index. Annulus depth was lower (flatter) in ASTR compared to both VSTR groups. For the RA, annulus to roof distance was larger in VSTR patients with AF, but the diameter width was wider for both ASTR and VSTR with AF. Indexed RA volume was larger in the VSTR with AF compared to both ASTR and VFTR without AF. The RV, on the other hand, showed a wide base and narrow mid in the ASTR group, both a wide base and mid in the VSTR group with AF, and slightly narrower base and wider mid in the VSTR without AF. RV base-to-mid ratio was lower for both VSTR groups compared to ASTR, but volumes did not significantly differ. RA-to-RV-volume ratio, however, was higher for the ASTR and VSTR with AF. Conclusion Remodeling of the TA and right chambers differ significantly between TR etiologies. ASTR is characterized by a larger and flatter TA, a widened RA and RV base, narrow RV mid, and almost proportional RA-to-RV volumes. VSTR remodeling differs with the presence of AF, as those without AF have a smaller and deep TA, smaller RA, a proportional dilatation of RV diameters, and a larger RV compared to RA. Differentiating these patterns may be useful to guide future interventions.