3D Transthoracic Echocardiography in Atrial Fibrillation Treatment Strategies: From Imaging to Intervention and Back

Atrial fibrillation (AF) is increasingly recognized as a structural disease that profoundly affects right-heart geometry and valvular function. The development of three-dimensional transthoracic echocardiography (3D TTE) has enabled a more detailed, reproducible assessment of these changes, offering new insights into the interplay between AF, right-heart remodeling, and tricuspid valve dynamics [1]. The study of Tian et al. supports the role of 3D TTE as a valuable tool in therapeutic guidance and follow-up for AF-related tricuspid valve and right heart pathology, integrating it into clinical practice [2]. The study represents a valuable contribution to the growing body of evidence on the structural and functional implications of rhythm control therapy in persistent AF, specifically focusing on right heart (RH) and tricuspid annular (TA) remodeling after radiofrequency ablation (RFA) [2]. This commentary appraises available evidence on TA and right-heart remodeling in AF as assessed by 3D TTE, and explores the impact of rhythm control strategies, particularly catheter ablation, on reverse remodeling followed up by 3D TTE and its use in practice. The results of the study of Tian et al. present right-heart remodeling, following RFA in patients with persistent atrial AF [2]. The principal findings, reverse right atrial (RA) remodeling, improvement in right ventricular (RV) ejection fraction detected by 3DE but not 2DE, and reduction in TA circumference suggesting geometric normalization, are not only relevant because of the positive imaging markers, but also clinically relevant in this subset of patients. Compared with the AF group, RFA resulted in smaller TA dimensions, reduced AP diameter, and decreased total circumference, along with greater annular displacement, suggesting improved dynamic function [2]. By integrating two relevant control groups, non-ablated persistent AF and sinus rhythm subjects, the investigators provide a well-structured comparative framework to evaluate post-RFA remodeling dynamics. However, the results show that, when compared with controls, residual enlargement of the TA and increased leaflet tenting persisted, indicating that structural remodeling was incomplete [2]. Multivariate analysis demonstrated that RFA, younger age, absence of diabetes, smaller TA area, and lower TA height were independent predictors of annular reverse remodeling, with robust associations across sensitivity analyses [2]. These findings suggest that while RFA can mitigate AF-related structural remodeling, residual abnormalities can remain, underscoring the importance of early intervention and comprehensive management strategies to preserve right-heart geometry and function. The evidence that 3TTE detected functional improvement missed by 2DE reinforces the superiority and higher sensitivity of volumetric imaging for RV functional assessment, supporting findings from prior studies. These results support the notion that RFA-mediated rhythm restoration can partially reverse AF-induced right heart structural remodeling, particularly within the early 3-month post-ablation period. The finding that the RFA group had larger RA linear dimensions and right ventricular (RV) volumes compared with controls suggests persistent structural remodeling despite the intervention or may indicate that geometric enlargement has not yet translated into overt functional impairment [2]. Parameters such as annulus height and displacement showed phase-specific changes, highlighting the complex, dynamic nature of TA geometry, suggesting that the increased annular displacement in the RFA group may reflect improved contractile dynamics related to remodeling. When compared with controls, however, the RFA group still exhibited a larger TA index area in middle- and end-systole and greater leaflet tenting in end-systole, suggesting that while RFA mitigates annular dilation, it may not fully restore normal anatomy [2]. This aligns with previous literature indicating that atrial arrhythmia ablation can partially reverse atrial remodeling but may leave residual structural alterations, particularly in longstanding AF [10-12]. However, this dissociation between size and function is clinically important, suggesting that RFA may stabilize or slow functional decline rather than fully reverse chamber dilation. Moreover, the multivariate regression in this study identifies RFA, younger age, absence of diabetes, smaller TA area, and lower TA height as significant predictors of TA reverse remodeling [2]. The robustness of the association across multiple sensitivity analyses strengthens the inference that RFA contributes meaningfully to structural normalization of the tricuspid annulus. However, residual confounders cannot be excluded, and causality cannot be definitively established. Mainly, the disproportionate prevalence of significant TR in the non-ablated AF group introduces a potential confounding factor, because TR severity itself both reflects and drives TA and RA remodeling. Therefore, differences in TR burden could obscure or exaggerate the observed effects attributed to RFA. Although the authors acknowledge this imbalance, the absence of subgroup analysis by TR grade limits the ability to isolate RFA's independent contribution to remodeling. The evidence from other studies indicates that persistent AF induces progressive dilation and circularization of the tricuspid annulus, accompanied by flattening of its saddle shape [9, 10]. In this context, AF acts as a driver of “atrial functional TR,” a distinct phenotype in which right atrial enlargement and annular stretching are the principal mechanisms of regurgitation. Several investigations using 3D TTE have demonstrated that TA size and shape correlate more strongly with RA volume than with RV parameters, reinforcing the concept that annular remodeling in AF is primarily atrial-driven [10, 11]. Additionally, the cross-sectional nature of the comparison limits causal inference that would better clarify whether these structural differences are residual or progressive. In contrast to 2D, 3D TTE provides volumetric imaging, allowing direct planimetric measurement of TA area, perimeter, and saddle-shape configuration throughout the cardiac cycle [1, 3-5, 13-15]. The authors applied quantitative three-dimensional echocardiography (3DE) with Tomtec analytical software, an advanced imaging approach that allows more comprehensive assessment. Modern ultrasound systems enable full-volume or single-beat 3D acquisitions from standard apical views, making it feasible even in patients with irregular rhythms such as AF. Automated software now facilitates annular segmentation and quantification, reducing operator dependency and improving reproducibility, therefore allowing the 3D method to be more friendly for use in everyday practice [3-5, 13-15]. Muraru et al. established reference values for tricuspid annular geometry using 3D TTE in a large multicenter population, highlighting the effects of sex, age, and body size on TA dimensions [6, 8, 12, 14]. Subsequent validation studies have confirmed a strong correlation between 3D TTE–derived TA measurements and those obtained by 3D transesophageal echocardiography (TEE) with low interobserver variability, positioning 3D TTE as a practical and robust imaging modality for right-heart assessment in routine clinical practice [7, 8]. Therefore, automated software or artificial intelligence (AI) tools can now help to improve the feasibility and reproducibility of multiparametric assessment of right-heart structures in different pathologies, as well as AF, making it ready to use in everyday practice. As image quality, automation, and analytical precision continue to improve, 3D TTE is emerging as a front-line modality for right-heart assessment in AF [14]. The data of Tian et al. imply that in the risk stratification model, clinical characteristics of individual patients also must be considered. Future directions, including integration with AI-based image segmentation for comprehensive understanding morphology and mechanics of the right heart in AF, combined with clinical characteristics of AF patients, may enable individualized risk-prediction models and perhaps clinical and image-guided therapy. In conclusion, Tian et al. have found that RFA in patients with persistent AF was associated with partial reverse remodeling of the tricuspid annulus, including reduced annular dimension, and enhanced dynamic displacement. Younger age, absence of diabetes, and smaller baseline annular size independently predicted remodeling, highlighting confounding factors that may influence outcomes. These results underscore that while RFA can favorably modify right heart geometry, timely intervention and comprehensive management remain critical for optimizing structural and functional recovery. Overall, this study strengthens the evidence that RFA may facilitate early reverse remodeling of the RH and TA in persistent AF, as well as the feasibility of 3DTTE in practice. Identifying the subset of patients who will benefit from RFA in persistent AF will require individualized risk stratification not only based on imaging (morphological) data but also the understanding of confounding factors. Integrating these factors would strengthen the translational relevance of the imaging findings and clarify whether RFA-induced remodeling will translate into improved clinical function. The authors have nothing to report. Open access publishing facilitated by Sveuciliste u Zagrebu, as part of the Wiley - National and University Library in Zagreb Consortium Croatian Academic and Research Libraries Consortium agreement. The authors have nothing to report.