Restoration of cardiac function by setting the ventricular pacing at a lower range in an infant with congenital complete atrioventricular block and dilated cardiomyopathy.

Patients paced for congenital complete atrioventricular block are at risk of dilated cardiomyopathy. We report such an infant in whom the dilated cardiomyopathy resolved after adjusting the ventricular pacing range. The infant received an epicardial pacemaker soon after birth for the congenital complete atrioventricular block. He developed dilated cardiomyopathy 5 months after right ventricular pacing at 140 bpm, which is the mean physiological heart rate of the newborn and young infant. The cardiac function recovered gradually (left ventricular ejection fraction from 20% to 74%) after lowering the ventricular pacing rate to a range from 90 to 120 bpm. We suggest that pacing at heart rates that are within the mean physiological range may still be detrimental in young infants. Adjusting the pacing range may, at least in part, help to restore the ventricular function.