LV PACING PRESERVES VENTRICULAR SYNCHRONY AND FUNCTION IN CHILDREN WITH AV BLOCK AND STRUCTURALLY NORMAL HEART AS COMPARED TO RV PACING SITES: A MULTI-CENTER STUDY

Objectives: Chronic right ventricular (RV) pacing is often associated with left ventricular (LV) dysfunction. We investigated which pacing site carries least adverse effects on LV synchrony and function.
Methods: Cross-sectional data were collected from 10 centres on 73 children (<18 years) with complete AV block and structurally normal heart undergoing permanent pacing (>1 year) from the RV free wall (RVFW, N=26), RV apex (RVA, N=34) and LV apex or mid-lateral wall (LV, N=13) for a median of 5.3 (IQR 3.1 – 8.5) years . Echocardiographic analysis was performed in a core lab.
Results: In comparison of the 3 pacing sites LV pacing was associated with the highest biplane LVEF, shortest inter-ventricular mechanical delay (IVMD), shortest septal to posterior wall motion delay (SPWMD) and shortest septal to lateral mechanical delay as measured from circumferential strain (SLMD) (Table, median and IQR). Pacing from the RVFW (but not the presence of maternal anti Ro/La antibodies, pre-implantation LV size and function, age at implantation, duration of pacing, pacing mode and QRS duration) was the only significant multivariable predictor (OR 14.4, CI 2.4-86.3, P=0.004) of decreased LVEF (<50 %).
Conclusions: LV pacing carries best long-term preservation of LV mechanical synchrony and systolic function in children with complete AV block and structurally normal heart. RVFW pacing is a significant determinant of decreased LV function. (JJ and PK supported by the research project of University Hospital Motol MZOFNM2005).