The Role of QT Interval Rate Adaptation in Diagnosis of Congenital Long QT Syndrome in Children

Abnormal prolongation of the QTc interval on 12-lead ECG is associated with congenital long QT syndrome (LQTS) that manifested in severe cases ventricular arrhythmias and sudden cardiac death. At the same time nearly 10-36% of genetically positive for LQTS can have normal (

The Рurpose: Definition of availability of LQTS at children with maladaptation of QT interval.

Methods and Results: Ten children with maladaptation on ECG of them had the “Schwartz score” <=1 point- 8, 3 point - 2 and ten healthy controls aged 7 to 15. Average values of QTc interval had: in the supine position - 426±15 ms, by standing - 440±18 ms. After minimum exercise stress at 4 children QTc interval was shortened, at 6 was lengthened to 462-498 ms, average values of QTc interval 459±29 ms. By ten healthy controls children values of QTc interval are by standing and after exercise under 450 ms. Results of molecular genetic test: 7 of 10 children with maladaptation (70%) are revealed mutations in genes (in KCNQ1 - 1, in KCNH2 – 3, in SCN5A – 1, in ANKB – 2).

Conclusions: Evaluation of the QTс interval in the ortostasis and after exercise and identification maladaptation of QT interval may help in establishing the diagnosis of long QT syndrome in children.