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Prolonged QT dispersion in children with congenital valvular aortic stenosis.

BACKGROUND
Hypertrophied and ischemic cardiac muscle in patients with aortic valve stenosis becomes a potential source of ventricular cardiac arrhythmia that can lead to sudden death. Arrhythmia is associated with an abnormal duration of the action potential in a cardiac muscle cell. The aim of this prospective study was to analyze QT dispersion in children with different stages of aortic valve stenosis and different left ventricular mass indexes.


MATERIAL/METHODS
Sixty children with aortic valve stenosis were divided into 3 subgroups according to their pressure gradients. Sixty healthy children served as controls. Doppler echocardiography, standard 12-lead electrocardiography and 24-hour Holter monitoring electrocardiography were performed.


RESULTS
QT dispersion was significantly higher in children with aortic stenosis than in the control group. There were statistically significant positive correlation between QT dispersion and left ventricular mass index and between QT dispersion and pressure gradient. QT dispersion was significantly higher in 20 patients with aortic stenosis and ventricular arrhythmia than that in patients without arrhythmia. In children with a higher pressure gradient and a higher left ventricular mass index, more complex arrhythmia was found.


CONCLUSIONS
Risk of ventricular arrhythmia increases with the degree of aortic valve stenosis and cardiac muscle hypertrophy. QT dispersion is prolonged in children with aortic valve stenosis, particularly in patients with arrhythmia, and increases with pressure gradient and left ventricular mass index.