Leadless Pacemaker, Right Ventricular Pacing Burden, and Heart Failure.

BACKGROUND: The optimal right ventricular pacing burden (%RVP) threshold associated with heart failure (HF) in patients with leadless pacemakers (LPs) remains unclear, whereas thresholds of 20% and 40% have been commonly used in studies of transvenous pacemakers. OBJECTIVE: To assess the current %RVP cutoffs and explore how increased %RVP influences the HF risk in LPs. METHODS: This registry-based observational study included patients who underwent LP implantation from 2015 to 2025. Patients with a prior HF diagnosis were excluded. %RVP was obtained through PaceMateLIVE, a vendor-neutral remote monitoring platform. The primary outcome was the first recorded HF diagnosis. RESULTS: We included 3167 patients with single-chamber LPs. The mean age was 76±13 years, and 45% were female. The median baseline %RVP was 71% [8-98%]. Over 2.4 years, the median absolute %RVP difference was 5.5% [0.7-21.6%], and 577 (18%) patients had the primary outcome. Patients with higher baseline %RVP at 20% and 40% cutoffs had increased risks of HF compared to those with lower %RVP (P<0.05). A multivariable Cox model showed that time-varying %RVP was associated with a higher hazard of HF (per 10% increase, hazard ratio 1.035 [1.013-1.059]). CONCLUSIONS: Baseline RVP thresholds of 20% and 40% may help identify patients with LPs who are at increased HF risk. However, HF hazard increased progressively with increasing RVP burden. Given the lack of established upgrade pathways for current LP systems, careful patient selection and follow-up may be particularly important for patients expected to have a high pacing burden.