Clinical and genetic characteristics and course of congenital long QT syndrome in children: A nine-year single-center experience

OBJECTIVE: Long QT syndrome (LQTS) is an inherited primary arrhythmia syndrome associated with life-threatening ventricular arrhythmias and sudden death. This study aimed to report the clinical and genetic characteristics and outcomes of children diagnosed as having LQTS in a tertiary pediatric cardiology center in Turkey. METHODS: This was a retrospective review of pediatric patients diagnosed as having LQTS at our center from January 2011 to April 2020. RESULTS: A total of 145 patients (76 males) were included, with a mean age of 9.2±4.5 years and a mean weight of 35.7±18.5 kg; 38 (26.2%) were identified as having LQTS during family screening, whereas a significant proportion of patients were asymptomatic at presentation, 15 patients (10.3%) were diagnosed after previous cardiac arrest, and 26 patients (18%) had syncope. The mean Schwartz score was 4.5 points (range, 3–7.5 points). Furthermore, 107 patients (82%) were confirmed to have a pathogenic mutation for LQTS genes. All patients received beta-blockers. Implantable cardioverter-defibrillator insertion was performed in 34 patients (23.4%). Left or bilateral cardiac sympathetic denervation was performed in 9 patients (6.2%). Median follow-up time was 35.6±25.8 months. Five (3.4%) patients died during the follow-up. Statistical analyses of risk factors for major cardiac events revealed that the QTc was >500 ms and that T wave alternans, high Schwartz score, and Jervell and Lange-Nielsen syndrome were strong and significant predictors of cardiac events. CONCLUSION: LQTS has a variety of clinical manifestations. Patients’ symptoms ranged between asymptomatic and sudden cardiac death (SCD). By raising the awareness of physicians regarding the disease, SCD might be prevented in the early period.