Abstract Body (Do not enter title and authors here): BACKGROUND
Leadless pacemakers (LPMs) have emerged as an alternative to transvenous pacemakers (TVPMs), particularly in patients with certain comorbidities. However, their long-term effects on tricuspid valve (TV) function remain unclear, with conflicting data from observational studies. Therefore, the LEADLESS-TR study aimed to assess the impact of LPMs versus TVPMs on TV dysfunction, left ventricular ejection fraction (LVEF), and major adverse cardiovascular events (MACE) in a real-world, multicenter cohort.

METHODS
Patients who received LPM or dual-chamber TVPM implantation between 2015 and 2024 were identified across three high-volume hospitals within the Allina Health System (Minneapolis, MN). Inclusion criteria included baseline echocardiography within two years prior to implantation and ≥1 follow-up echo. Exclusion criteria were prior pacemakers, prior TV interventions, or baseline TR worse than moderate. Propensity score matching (1:1) was performed based on age, sex, implant year, and baseline LVEF. Multivariate Cox models were implemented to compare outcomes between the two groups after adjusting for BMI, chronic kidney disease, diabetes, and baseline TR. Outcomes included: (1) ≥1 grade TR worsening, (2) >10% LVEF reduction, and (3) MACE (a composite of cardiac death or heart failure hospitalization). Follow-up continued until death, device removal, TV intervention, or last clinical contact.

RESULTS
Of 540 LPM patients, 241 met inclusion criteria and were matched to 241 dual-chamber TVPM patients (Table 1). The mean age was 78+6 years, and 37% were females. Mean follow-up duration was longer in the LPM group (2.96 vs. 2.43 years). LPMs were associated with a non-significantly higher hazard of TR progression compared to TVPMs (HR 1.17, 95% CI: 0.87–1.57, p=0.30) (Table 2A). Similarly, there was a non-significant trend toward lower LVEF with LPMs (HR 0.86, 95% CI: 0.57–1.31, p=0.50) (Table 2B). MACE rates were also comparable between groups (HR 1.08, 95% CI: 0.79–1.49, p=0.60) (Table 2C).

CONCLUSION
In this multicenter propensity-matched cohort, LPMs offered no significant advantage over TVPMs in preserving TV function, LVEF, or reducing MACE, even after adjusting for comorbidities. These findings challenge the assumption that leadless systems are universally beneficial for the TV and highlight the need for prospective head-to-head studies with advanced imaging to elucidate any potential device-valve interactions and guide device selection and location.