113 The impact of right ventricular pacing burden on thoracic impedance and heart rate variability in pacemaker patients

Background Pacing induced cardiomyopathy (PICM) occurs in up to a quarter of patients at long term follow up. Lower heart rate variability (HRV) and thoracic impedance (TI) levels are seen in patients with heart failure. Remote monitoring of HRV and TI in pacemaker patients could demonstrate the adverse effect of RV pacing. Aim To demonstrate the adverse effects of incremental increases in right ventricular pacing in pacemaker patients using remote monitoring. Methods One year of anonymised remote monitoring data from 1159 pacemaker patients was analysed. Clinical data were unavailable. Each remote monitoring day was grouped based on the right ventricular (RV) pacing percentage to produce ten equal groups. Days of sinus rhythm were compared with days of paroxysmal atrial fibrillation 1–23 hours, and persistent atrial fibrillation >23 hours. Heart rate variability was recorded as the P-P interval and therefore is only reported during the periods of sinus rhythm. Mean thoracic impedance and median heart rate variability were analysed. Results Right ventricular pacing >30% caused a deterioration in thoracic impedance, particularly during days of paroxysmal atrial fibrillation (AF). Each incremental 10% increase in RV pacing caused a reduction in HRV during days of paroxysmal AF. Across all groups, a subset of patients who are paced >80% have preserved heart rate variability and higher thoracic impedance (figures 1 and 2). Conclusion In paroxysmal atrial fibrillation, increasing RV pacing percentage has a detrimental impact on heart rate variability. Some patients with a very high burden of RV pacing (Conflict of Interest I have received fellowship funding from Abbott and educational support from Biotronik