The Impact of Pacemaker Programming on Morbidity in Heart Transplant Recipients

Pacemaker programming recommendations in patients post-heart transplant include a higher lower rate limit, activating rate response mode, maximising battery longevity and minimising ventricular pacing in patients without atrioventricular block. This study sought to investigate how variability in pacemaker programming following orthotopic heart transplant affects morbidity. We conducted a retrospective analysis of heart transplant recipients at a single transplant centre between 1991 and 2023. Patients requiring pacemaker implantation following transplantation were matched with non-pacemaker recipients by age, sex and height. Patient and device characteristics were reviewed. Clinical outcomes, programming and physiological parameters were compared within the pacemaker group and between subject and comparator groups. Forty-five heart transplant recipients were included: 15 with pacemakers and 30 without. Within the pacemaker group, 20% were programmed with LRL > 60 bpm, rate-response mode in 47% and algorithms minimising ventricular pacing in 27%. Fifty-three percent were NYHA class I, and 46% NYHA class II; resting heart rate was similar between the groups (85 (SD14.9) and 79 (SD8) bpm: p = 0.33). NYHA class I group achieved a higher workload (METS 9 (SD2.7) vs. 6.9 (SD1) mL/kg/min: p = 0.21), and peak heart rate (135 (18.8) vs. 123 (14.8) bpm: p = 0.29) during exercise stress echocardiogram (ESE). The pacemaker group was more symptomatic than the comparator group (NYHA class II 46% vs. 10%: p = 0.016) and exhibited higher rates of cardiac allograft vasculopathy (53% vs. 10%: p = 0.005). There is substantial variability in pacemaker programming in heart transplant recipients. Patients who require a pacemaker have a greater symptom and comorbidity burden than those without. No identifiable physiological or programming differences stratified the greater morbidity within the pacemaker cohort.