The Frequency of Congenital Long QT Syndrome Based on New Formula in Children with Sensori-Neural Hearing Loss

Abstract

Introduction: Long QT syndrome (LQTS) is a repolarization cardiac disorder that can lead to syncope, cardiac arrest and sudden death in apparently healthy individuals. The congenital type can be accompanied with congenital sensory-neural deafness (Jervell-Lang-Nielsen syndrome). Although there are limited studies assessed the frequency of LQTS in these children in developed countries, regarding introducing the new formula, it is necessary to re-evaluate the frequency of this syndrome. Materials and Methods: This cross-sectional and descriptive study was done on 203 patients with congenital sensory-neural hearing loss (SNHL) that had cochlear implant surgery in Baqiyatallah cochlear implant center from 2008 to 2012. Corrected QT was calculated with this formula: QTC = QT + 1.75 (heart rate-60) Patients with QTC > 460 ms, were categorized in four groups: Long QT: QT > 460, Borderline: 440 < QTC ≤ 460, markedly long QT: QTC > 470 and very markedly: >500. Also, cardiac arrhythmias or arrest were evaluated in patients during cochlear implant surgery and in the postoperative recovery period. Result:Prevalence of LQTS in patients was 12.32% (25 patients). Prevalence of markedly long QT and very markedly long QT were 8.87% (18 patients) and 2.46% (5 patients) respectively. The prevalence of borderline group was 14.29% (29 patients). None of the patients during or after surgery were affected by cardiac arrhythmias or arrest. Conclusion: This study showed higher prevalence of LQTS in patients with SNHL than the normal population, and we suggest that all patients with congenital deafness should be screen for LQTS.