Exploring Imaging Depth: A Pilot Study About 2D vs. 4D Echocardiography for Tricuspid Valve Evaluation

Background: The tricuspid valve (TV) is a complex three-dimensional (3D) anatomical structure; however, current guidelines recommend tricuspid annulus (TA) measurements to be performed with two-dimensional (2D) echocardiography. The aim of this study was to compare TV measurements obtained with 2D and four-dimensional (4D) echocardiography for surgical planning. Methods: All echocardiographic data of patients referred to our center for TV assessment were collected. Multimodality imaging data were reviewed, including 2D transthoracic echocardiography (TTE) integrated with information from 3D TTE. Measurements were also compared with those obtained using the 4D Auto Tricuspid Valve Quantification (TVQ) tool. Results: Overall, 11 patients (median age 72 [66–78] years, 18% female) were included in the study. Mild, moderate and severe tricuspid regurgitation (TR) was present in 6, 3 and 2 patients, respectively. Systolic pulmonary artery pressure was 35 ± 8 mmHg, inferior vena cava diameter 21 ± 4 mm, right atrial area 25 ± 9 cm2 , 4D ejection fraction 45 ± 7%, 4D fractional area change 40 ± 6%, and tricuspid annular plane systolic excursion 21 [15–25] mm. 2D/4D right ventricular-basal diameter (RVD1) was significantly different (p < 0.005). Similarly, 2D/4D right ventricular diameter measured at the level of the left ventricular papillary muscles (RVD2) was significantly different (p < 0.012), as well as 2D/4D tricuspid annular diameter (p = 0.020). Despite these differences, a strong correlation between variables was observed (Spearman correlation coefficient >0.824). In evaluating the correlation between TR severity and analyzed variables, RVD1 was related to TR severity both at 2D and 4D echocardiography. Conversely, RVD2 and TA diameter were significantly associated with TR severity only at 4D echocardiography. Conclusions: Our results suggest that specific patient subsets could benefit more from TA measurements using the 4D Auto TVQ tool to help identify the mechanisms responsible for TR, including candidates for left-sided valve surgery and patients in whom the indication for TV repair is unclear.