Evolution of left ventricular function in paediatric patients with permanent right ventricular pacing for isolated congenital heart block: a medium term follow-up.

Aims: We aimed to assess the evolution of left ventricular (LV) systolic function in children with right ventricular apical (RVA) pacing for isolated congenital heart block (ICHB) and to identify possible predictors of LV function deterioration. Right ventricular apical pacing can be detrimental to LV function in a significant number of adults. Effects in children are still controversial.

Methods And Results: Left ventricular shortening fraction (LV SF) and QRS duration were retrospectively assessed in 45 children with RVA pacing for ICHB: before pacemaker (PM) implantation, immediately after and then regularly during a follow-up of 58.69 +/- 45.23 months. Patients were categorized as stable or deteriorators according to an arbitrarily chosen cut-off point of > or =7% decrease in LV SF. Lupus status was unknown. Overall LV SF did not change significantly (41.42% +/- 8.21 before pacing, 39.77% +/- 7.03 immediately after PM implant, 37.43% +/- 9.91 with chronic pacing, P = NS). Deteriorators (n = 13) had significantly higher baseline heart rate (57.5 +/- 8.7 vs. 46.9 +/- 10.5 bpm, P < 0.05) and baseline LV SF (46.17 +/- 8.13 vs. 38.4 +/- 6.4%; P < 0.05), a significantly higher proportion of them being implanted before 2 years of age: 8 of 13 (61.5%) vs. 5 of 25 (20%) in the stable group (P < 0.05). Deteriorators had a higher incidence of an initial epicardial lead and narrower native QRS.

Conclusion: Permanent RVA pacing for ICHB does not necessarily affect LV function in children. The risk of deterioration of LV function seems to be higher in children with higher baseline heart rate and better baseline LV SF, especially with pacing at a younger age, a narrower native QRS and RVA epicardial pacing site.