Permanent pacing in children with isolated congenital complete atrioventricular block may cause left ventricular dysfunction. To prevent it, alternative pacing sites have been proposed: left ventricular epicardial or selective right ventricular endocardial pacing.

To compare the functional outcome (left ventricular systolic function and synchrony) in paediatric patients with congenital complete atrioventricular block and left ventricular apical epicardial or right ventricular transvenous mid-septal pacing.

Retrospective study. Epicardial leads were implanted by standard surgical technique, transvenous leads by 3D electroanatomic mapping systems. 3D mapping acquired 3D right ventricular local pacing map and defined the narrowest paced QRS site. 3D mapping guided screw-in bipolar leads on that ventricular site. Electrocardiogram (ECG) (QRS duration) and echocardiographic data (synchrony: interventricular mechanical delay, septal to posterior wall motion delay, systolic dyssynchrony index; contractility: global longitudinal strain, ejection fraction) were recorded. Data are reported as median [interquartile ranges]. p < 0.05 was significant.

There were 19 transvenous systems (age 8.8 [6–14] years; right ventricular mid-septum) and 17 epicardial systems (0.04 [0.001–0.6] years; left ventricular apex). Post-implantation QRS significantly widened either in endocardial or in epicardial patients. Most patients reached 4-year follow-up. One-year and 4-year ejection fraction and global longitudinal strain were mostly within normal limits and did not show significant differences between the two groups and between the same endocardial/epicardial group. Synchrony parameters were within normal limits in the two groups.

Left ventricular apical epicardial pacing and 3D mapping-guided right ventricular mid-septal pacing preserved left ventricular contractility and synchrony in children and adolescents with congenital complete atrioventricular block at short-/mid-term follow-up, without relevant significant differences between the two groups.