Clinical Analysis Of Five Families With Hereditary Long QT Syndrome

ObjectiveHereditary Long QT syndrome(LQTS)is a type of abnormal function of cardiac ion channels due to mutations in the genes encoding cardiac ion channels and related proteins.The clinical manifestations are prolonged QT interval,which often leads to ventricular arrhythmias and Tosade de points ventricular tachycardia.LQTS are autosomal dominant or recessive inherited heart disease,which is closely associated with sudden cardiac death in young adults.In this study,5 hereditary LQTS families were selected and the clinical characteristics,genotype and treatment of the families were retrospectively analyzed,and the prognosis was evaluated through follow-up.MethodsFive families,two LQT1,two LQT2 families and one LQT5,diagnosed as LQTS by genetic testing in the Department of Cardiology of Xi ’an Children’s Hospital from January2006 to September 2020 were selected as the study subjects.A total of 12 patients aged 3-52 years were included,including 6 male and 6 female patients.Collect and analyze general data(gender,age),clinical symptoms,ECG and other auxiliary examination data and treatment,design a follow-up table,through outpatient or telephone follow-up,summarize and analyze the clinical data and treatment effect of patients.Results1.There were 12 patients with LQTS from 5 LQTS families,including 6 males and 6females.The patients were from 3 to 52 years old,and the age of first onset ranged from 8months to 36 years old.Eight patients presented with syncope episodes,of which 5 patients had a clear trigger,presenting themselves as intense exercise and/or mental stress.Four patients were asymptomatic,including 2 patients with normal QTc and 2 patients with prolonged QTc.2.The gene mutations of the five LQTS families were identified which family 1KCNH2 c.797C>T(p.S266F);Pedigree 2 KCNQ1 c.1032G>A(p.A344A);Pedigree 3KCNQ1 c.1024C>T(p.L342F);Pedigree 4 KCNE1 c.226G>A(p.D76N);Family 5 KCNH2 c.1810G>A(p.G604S),all of which were known variants included in HGMD(Human genome mutation database).3.The electrocardiogram has gene-specific manifestations,which are as follows: LQT1 has broad basal T wave,LQT2 has low amplitude and notch T wave.4.12 cases of LQTS patients,7 cases treated with beta blockers and 5 were not treated,and none had syncope episodes during the follow-up period(1 to 14 years).5.According to the risk assessment based on the rating criteria,1 of the 5 LQTS patients who were not treated with β-blockers were in the high risk group,1 was in the medium risk group,and 3 were in the low risk group.Conclusion1.All the cases included in this study had clear pathogenic genes and mutation sites,which were in line with autosomal dominant inheritance characteristics.2.There was no syncope episode in all patients during the follow-up period,and β-blockers were effective in treating LQTS...