摘要BACKGROUND:Long QT syndrome(LQTS)is a heterogeneous syndrome that may be congenital or,more frequently,acquired.The real-world prevalence of acquired LQTS(aLQTS)in the emergency department(ED)remains to be determined.The aim of this study was to determine prevalence of aLQTS and its impact on symptoms on ED admissions.METHODS:Electrocardiograms(ECG)of 5,056 consecutively patients admitted in the ED of a tertiary hospital between January 28th and March 17th of 2020 were reviewed.All patients with aLQTS were included.Clinical data with a focus on QT prolonging drugs and clinical factors were recorded.Statistical comparison was made between the groups with and without corrected QT(QTc)interval greater than 500 ms(value that is considered severely increased).RESULTS:A total of 383 ECGs with prolonged QTc were recognized,corresponding to a prevalence of aLQTS at admission of 7.82％.Patients with aLQTS were more commonly men(53.3％)with an age of(73.49±14.79)years old and QTc interval of(505.3±32.4)ms.Only 20.4％of these patients with aLQTS were symptomatic.No ventricular arrhythmias were recorded.Patients with QT interval greater than 500 ms were more frequently female(59.5％;P＜0.001)and were more frequently on QT prolonging drugs(77.3％;P=0.025).Main contributing factor was intake of antibiotics(odds ratio[OR]4.680)followed by female gender(OR 2.473)and intake of antipsychotics(OR 1.925).CONCLUSION:aLQTS is particularly prevalent in the ED.Female patients on antibiotics and antipsychotics are at particularly high risk.Efforts must be made to avoid,detect and treat aLQTS as early as possible.