• 3D ETT
• CIED-related TR
• CIED-TR
• tricuspid regurgitation

Background and aims: Tricuspid regurgitation (TR) progression, either as a new onset TR or as a worsening of a pre-existing TR, has been widely reported following cardiac implantable electronic devices (CIEDs) implantation. Two categories have been described according to the prevalent mechanism: CIED-related and CIED-associated TR.
This study aimed to identify the incidence of TR progression after right ventricular (RV) lead implantation, the differences between CIED-related and CIED-associated TR and its relation to the lead position inside the tricuspid annulus with the use of three-dimensional transthoracic echocardiography (3D TTE).
Methods: In this prospective, non-randomized, cohort study, consecutive naïve patients who underwent pacemaker (PM), implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy (CRT) implantation between January and June 2024 were enrolled. All patients underwent a complete 2D ETT before transvenous lead implantation and after 6 months with a 3D ETT in order to evaluate device lead position inside the tricuspid annulus (TA) and lead interference with leaflets motion. For each patient new onset or progression of TR was assessed using vena contracta (VC) width and classified as CIED-related (Group 1) or CIED-associated (Group 2) based on the 3D findings. TR worsening was defined as an increase of at least one grade between pre- and post- implantation echocardiograms. I
Results: Of the 63 patients enrolled (mean age 74 ± 8 years), 12 patients (19%) experienced worsening TR during follow-up. 45 patients (71.4%) had a PPM, 18 (28.6%) had an ICD, and 12 (19%) had CRT devices. The 3D TTE technique successfully identified the lead position at the level of TA in 58 cases (92.1%), allowing the relationship’s description as commissural in 48 (76.2%) and non-commissural (located on a leaflet) in 10 patients (15.9%). In 5 patients (7.9%), 3D reconstruction was inconclusive for the definition of the lead position. A total of 13 patients (20.6%) had CIED-related TR, while the remaining 50 patients (79.4%) had CIED-associated TR. The study found a significantly higher rate of TR progression in the CIED-related group, with lead impingement against a leaflet and lead adherence to a leaflet as the main contributor. A commissural lead position was associated with a protective effect (HR 0.12, CI 0.31 - 0.45, p=0.002), whereas non-commissural lead placement increased TR severity (HR 8.44, CI 2.22 - 31.97, p=0.002). Multivariate analysis identified only septal leaflet impingement (aHR 14.29 CI 3.17- 64.45, p=0.006) and posterior leaflet adherence (aHR 8.58 CI 1.75 – 42.17, p 0.003) as independent risk factors for TR progression, suggesting that some leaflets could be more affected by specific lead interactions.
Conclusions: 3D TTE offers valuable insights into the interaction between the lead and the tricuspid valve. Its ease of use and straightforward execution make it a highly accessible tool in clinical practice. However, further studies with larger patient cohorts and extended follow-up are pivotal to fully elucidate the spectrum of potential mechanical interactions and their long-term impact on TR progression.