The long QT syndrome in pediatric age: prognosis and risk factor

Long QT syndrome is a rare arrhythmic disease with a low incidence in the general population. There are no sure clinical or electrocardiographic parameters that could lead to a correct prognostic stratification in patients affected by this syndrome. The correlation between the incidence of a sudden death or dangerous ventricular arrhythmias and the duration of QTc interval is still a controversial topic.

Twenty nine children affected by QT long syndrome were admitted to the Division of Pediatric Cardiology of the Casa del Sole Hospital of Palermo (Italy). Their diagnosis was made by electrocardiogram (ECG). The average age of the patients was 7.6 years. The average follow-up was 4 years and three months. A therapy with beta-blocker was administered to all the children. During the follow-up of 4 year and three months, patients were genotyped. Twenty-three out of 29 children had at least one relative affected by the syndrome. Three of them had a familiar dead because of this syndrome and everyone had a duration of maximum QTc higher than the cut off (P=0.0002). All the people who died had not followed the therapy with beta-blocker. Patients with a maximum QTc recorded <500 had not familiar death by this syndrome.

Holter and echocardiogram recorded periodically during the observation did not show dangerous arrhythmic events. All children maintained a good health during the follow-up.

Although conducted on a small study population, the data analysis recorded during this study suggests that in patients affected by QT long syndrome younger than 16 years old undergoing a beta-blocker therapy the prognosis is excellent. The duration of QTc interval appears as a negative prognostic factor, although the beta-blocker therapy has been reduced considerably the incidence of sudden death.