Improvement of left ventricular function after changing the pacing site in a child with isolated congenital complete atrioventricular block and dilated cardiomyopathy

We report a case of isolated congenital complete atrioventricular block with left ventricular dysfunction after pacemaker implantation that improved after the pacing site was changed. During the neonatal period, a pacemaker wire was implanted on the right ventricular epicardium and pacing was initiated. Decreased ejection fraction and a perfusion defect around the septum on myocardial scintigraphy were observed during follow-up. Induced left bundle branch block was thought to be causing interventricular asynchrony, and the pacing site was change to the left ventricular epicardium. Ejection fraction improved and the perfusion defect resolved. Lead relocation may be useful for left ventricular dysfunction that develops during right ventricular pacing.