ABSTRACT
Objective:To explore the pathogenic genes, clinical characteristics and treatment follow-up of children with congenital long QT syndrome (LQTS).Methods:Clinical data of 20 cases diagnosed with congenital LQTS and underwent gene testing from April 15, 2011 to April 15, 2021 in Department of Pediatric Cardiology, Shandong Provincial Hospital Affiliated to Shandong University were retrospectively collected and analyzed using independent sample t-test and Fisher′ s exact probability method. Results:LQTS-related gene mutations were detected in all the 20 cases, and pathogenic or suspected pathogenic mutations were identified in 18 cases (90.0%). Five LQTS mutation genes were discovered, including KCNQ1, KCNH2, SCN5A, CACNA1C and AKAP9.Eighteen cases (90.0%) had positive symptoms, and 13 cases (65.0%) had definite inducements.The inducement of symptoms in children with LQTS type 1(LQT1) was related to exercise, the causes of syncope in LQT1 and Jervell-Lange-Nielsen syndrome type 1 (JLNS1) with complex heterozygous mutations were exercise or emotional agitation; the causes of syncope in LQTS type 2 (LQT2) were unrelated to exercise; severe exercise in LQTS type 3 (LQT3) resulted in symptoms; and seizure in LQTS type 8 (LQT8) was non-induced.The corrected QT(QTc) interval of 20 cases was (553.1±66.6) ms, with a range of 460-707 ms, among which 17 cases showed QTc≥480 ms.The electrocardiogram(ECG) manifestations of children with various types of LQTS were different.There was no significant difference in QTc between different genders, or between children with syncope and those without syncope (all P>0.05). The follow-up time was (3.4±2.3) years, ranging from 0 to 8.3 years.Seventeen children received treatment[beta blockers and implantable cardiovertor-defibrillator(ICD)] and 3 cases did not.By the end of the follow-up, 1 child died, 19 cases survived, and 2 cases of the surviving children lost consciousness. Conclusions:There is a high consistency between genetic diagnosis and clinical diagnosis of congenital LQTS.The positive rate of gene detection is 90.0%.The clinical manifestations and ECG characteristics vary with genotypes.Beta blockers are protective.ICD therapy can prevent sudden cardiac death when oral medication does not respond.