BackgroundThe expansion of tricuspid valve (TV) interventions has underscored the need for accurate and reproducible 3D transthoracic echocardiography (TTE) tools for evaluating the tricuspid annulus (TA) and for 3D normal values of this structure. We aimed to: develop new semi-automated software for 3DTTE analysis of the TA, compare its accuracy and reproducibility against multiplanar reconstruction (MPR) reference, and determine normative values. Methods3DTTE images of 113 patients with variable degrees of tricuspid regurgitation were analyzed using the new semi-automated software and conventional MPR methodology (as the reference standard), each by 3 independent readers. For each measured parameter, inter-technique agreement was assessed using linear regression and Bland-Altman analyses, and inter-reader variability using intraclass correlation (ICC) and coefficients of variation (CoV). Additionally, 3DTTE datasets of 789 subjects from the WASE Study were analyzed using this new software to determine normal values for each TA parameter. ResultsSemi-automated measurements showed excellent agreement with MPR reference values for all TA measurements: high correlations (all r-values >0.8) and minimal biases. All measurements were more reproducible than with MPR: higher ICC values (0.94-0.96 vs 0.82-0.90), and lower CoV (5-12% vs 8-18%). Sex- and age-related differences were identified in 3D normal values of most TA parameters. Dynamic analysis showed that TA parameters vary throughout the cardiac cycle, reaching minimal values at end-systole and maximum values in late diastole. ConclusionNovel software for semi-automated analysis of the TA geometry and dynamics provides accurate and reproducible measurements. Normal values of TA dimensions, parsed by sex and age, are hereby reported.