Pacemaker Indications and Long-Term Stability of Pacing Indices in Heart Transplant Recipients

Approximately 10% of heart transplant (HT) recipients require a pacemaker (PM) implant. Despite graft-related complications such as rejection, cardiac allograft vasculopathy and fibrosis, there is no evidence on the long-term stability of pacing indices. Moreover, one of the most common indications for PM implant is early post-transplant sinus node dysfunction (SND), although this is reversible in many cases.

A retrospective observational study including all HT recipients at our institution who underwent permanent PM implantation between April 1991 and January 2023 was conducted. The incidence of PM implantation, indications for PM implantation and changes in pacing indices were evaluated. A total of 861 adult HT were performed (92.1% using bicaval anastomosis technique), and 46 received a permanent pacemaker (cumulative incidence 5.3%) over a median follow-up of 7.9 years (IQR 2.5-15.1 years). Only one patient (2%) received a PM due to early post-HT SND. The median PM follow-up time was 5.4 years (IQR 2.0-8.1 years). Atrial and ventricular leads showed an initial impedance drop (p < 0.001 both) and an initial capture threshold increase (p < 0.001 and p = 0.003, respectively) with subsequent stabilization. R-wave amplitude remained stable, but there was a drop in P-wave amplitude (p = 0.026).

Pacing indices remained stable and showed a behavior similar to that of native hearts except for a progressive decrease in P-wave amplitude, suggesting the need to aim for the highest possible P-wave amplitude during implantation.