Conduction system pacing guided by 3d-electroanatomic mapping system preserves systolic function in paediatric patients

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. BACKGROUND/INTRODUCTION: Paediatric transvenous permanent pacing from alternative ventricular sites including conduction system pacing may prevent ventricular dyssynchrony and systolic dysfunction. These procedures may be difficult and require higher fluoroscopic exposures. The use of three-dimensional-electroanatomic mapping system (3D-EAM) may guide lead implantation toward these alternative sites and reduce fluoroscopic exposure. PURPOSE: of this study is the outcome of 3D-EAM-guided alternative sites pacing in paediatric patients. METHODS: Retrospective analysis of children and young patients with congenital or acquired complete atrioventricular block (CAVB) with or without other congenital heart disease (CHD) who underwent 3D-EAM-guided transvenous pacing in alternative sites of the subpulmonary ventricle, to perform non-selective His bundle pacing (NSHBP), pacing of ventricular septum close to conduction system (VS-CSP) or outflow tract (OT). 3D-pacing map guided stylet-directed screw-in lead implantation toward septal sites with narrower paced QRS. Procedure and follow-up data were recorded. Parameters of ECG (QRS duration, left ventricular activation time, LVAT), echocardiogram (3D ejection fraction, EF, global longitudinal strain, GLS, of the systemic ventricle) and lead (threshold, sensing) were registered and compared at baseline (pre-implantation) and during follow-up (1-3-year). Data are reported as median (25th-75th centiles). P<0.05 was significant. RESULTS: 64 patients (47 females) with CAVB, of whom 11 with CHD, underwent 3D EAM-guided pacing (31 VVIR, 33 DDD) at age 12 (8-15) years, weight 44 (27-57) kg. Prior pacing (RV apex, RV and LV free wall, also biventricular) was present in 27 patients. Pacing sites were: 10 NSHBP, 5 RVOT, 49 VS-CSP (Figure 1). Procedure time was 175 (146-200) min, fluoroscopy exposure was: 3.0 (1.2-5.0) mGy and 90 (33-146) microGy/m2. Echographic parameters at baseline and follow-up are reported in Table 1. Baseline QRS duration 85 (80-130) ms, increased after implantation, 115 (100-120) ms (P=0.002), with LVAT 80 (70-81) ms (Figure 1). In patients with prior pacing, QRS shortened post-implantation: QRS 130 (120-160) vs. 120 (110-125)ms (P=0.004). Lead parameters were good post-implantation and at 3-year follow-up: threshold 0.5 (0.4-0.7) vs. 0.9 (0.7-1.2)V/0.5 ms; R-wave sensing 9 (6-12) vs. 7 (4-9)mV. Four NSHBP patients showed lead dislodgement requiring lead repositioning. CONCLUSIONS: 3D-EAM-guided alternative site pacing was accomplished with low fluoroscopic exposure. Paced QRS duration was significantly broader than in junctional rhythm but it was significantly narrower than prior epi/conventional site endo pacing. This pacing approach preserved ventricular systolic function in paediatric patients with CAVB at mid-term follow-up. [Figure: see text] [Figure: see text]