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

Olga Podshivalova
Research Clinical Institute for Pediatrics of the N.I. Pirogov, Russian National Research Medical University, Russia

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.