Editorial: Added value of 3D imaging in the diagnosis and prognostication of patients with right ventricular dysfunction

Right ventricular (RV) function is an important prognostic factor in various cardiovascular conditions, such as in heart failure with reduced and preserved left ventricular (LV) ejection fraction (EF) or in pulmonary arterial hypertension [1]. The quantification of RV function is also a cornerstone of perioperative risk assessment [2] and the management of patients with mechanical circulatory support devices or adults with congenital heart disease [3]. Nevertheless, the precise assessment of RV function is challenging due to the complex geometry and mechanics of the RV. Three-dimensional (3D) imaging techniques may help clinicians overcome some of these hurdles, allowing them to capture even subtle changes in RV function related to pressure-and volume overload [4], which may be undetectable using conventional imaging markers. Thus, novel 3D imaging-based parameters of RV function may improve diagnostics and prognostication in numerous diseases [5]. This Research Topic comprises articles providing valuable insights into the intricacies of RV mechanics in both health and disease and showing the added value of 3D imaging in diagnosing RV dysfunction and predicting outcomes.Using cardiac magnetic resonance (CMR) imaging -the gold-standard imaging modality for assessing RV size and function, a group of investigators analyzed the RV myocardial architecture in two separate articles. In the first one, Kiss et al. described the ageand sex-specific characteristics of RV compacted and trabeculated myocardium using CMR in 200 healthy volunteers. They found that RV compacted (RV-CMi) and trabeculated myocardial mass indices (RV-TMi) were higher in men than in women, and the RV-TMi decreased with advancing age in the latter group. Furthermore, LV-CMi and LV-TMi, RV end-systolic volume, and sex were independent predictors of RV-TMi. In the second article, Kiss et al. measured RV volumetric, functional, and feature-tracking strain parameters in 100 patients with LV noncompaction (LVNC) phenotype and normal LVEF and compared them to those of 100 age-and sex-matched healthy controls. Authors observed that patients with LVNC had higher RV volumes and lower RV global and septal strain values than controls. Twenty-two percent of the analyzed LVNC patients had an RV-TMi above the reference range, and these patients had higher biventricular volumes, lower biventricular EFs, and worse RV strain than patients with normal RV-TMi. Moreover, there was a strong positive correlation between RV-TMi and LV-TMi, and both showed inverse relationships with RV function.Besides CMR imaging, 3D echocardiography also has a crucial role in assessing RV size and function. Importantly, 3D echocardiography-derived parameters (e.g., RVEF) have significant prognostic utility, which was also demonstrated by Nabeshima et al. in 392 patients with asymptomatic aortic stenosis (AS). They found that a lower RVEF at baseline was associated with an increased risk of cardiac events. Moreover, RVEF had incremental prognostic value over indexed aortic valve area, LVEF, and two-dimensional echocardiography-derived RV parameters. Beyond the assessment of global RV function, 3D echocardiography, in combination with advanced post-processing software solutions, can also be used for the comprehensive analysis of the RV contraction pattern. One such tool is ReVISION -a thoroughly validated, FDA-cleared, commercially available software solution -which decomposes the motion of the RV along its three orthogonal axes (i.e., longitudinal, radial, and anteroposterior axis), quantifies the contribution of these three motion components to global RV function, and computes 3D RV longitudinal, circumferential, and area strains [6,7]. ReVISION has already been used to characterize the contribution of the three motion components in healthy adults [8,9]. However, this software solution has not yet been thoroughly tested in healthy pediatric hours after admission and found that RV systolic dysfunction is more pronounced in ARDS unrelated to SARS-CoV-2 than in SARS-CoV-2 ARDS. Moreover, when analyzing the RV contraction pattern using ReVISION, they observed that the contribution of radial shortening to global RV function was reduced in patients with ARDS unrelated to SARS-CoV-2 compared to the other two groups, whereas the contributions of the other motion components (i.e., shortening along the longitudinal and anteroposterior axes) were unchanged.Remaining in the realm of intensive care units and operating theatres, Keller et al.analyzed the associations between 3D transesophageal echocardiography-derived parameters of regional RV function and short-term outcomes in 357 patients undergoing elective cardiac surgery. They observed that a higher ratio of apical vs. inflow tract stroke volume (assessed using their previously published custom-made software solution [10]) was independently associated with the composite of in-hospital mortality and/or the need for extracorporeal life support, underlining the importance of RV evaluation on the segmental level.Acquiring 3D echocardiographic datasets suitable for 3D analysis might not always be feasible from the apical view. To explore whether 3D datasets can also be acquired from an