also be diagnosed if an individual has a schwartz score of greater than 3 or if a pathogenic genetic variant associated with lqts is identified, regardless of qt interval. treatment those diagnosed with lqts are usually advised to avoid drugs that can prolong the qt interval further or lower the threshold for tdp, lists of which can be found in public access online databases. in addition to this, two intervention options are known for individuals with lqts: arrhythmia prevention and arrhythmia termination. arrhythmia prevention arrhythmia suppression involves the use of medications or surgical procedures that attack the underlying cause of the arrhythmias associated with lqts. since the cause of arrhythmias in lqts is early afterdepolarizations (eads), and they are increased in states of adrenergic stimulation, steps can be taken to blunt adrenergic stimulation in these individuals. these include administration of beta receptor blocking agents, which decreases the risk of stress-induced arrhythmias. nadolol, a powerful non-selective beta blocker, has been shown to reduce the arrhythmic risk in all three main genotypes (lqt1, lqt2, and lqt3). genotype and qt interval duration are independent predictors of recurrence of life-threatening events during beta-blocker therapy. to be specific, the presence of qtc >500 ms and lqt2 and lqt3 genotype are associated with the highest incidence of recurrence. in these patients, primary prevention with use of implantable cardioverter-defibrillators can be considered. sodium channel blocking drugs such as mexiletine have been used to prevent arrhythmias in long qt syndrome. while the most compelling indication is for those whose long qt syndrome is caused by defective sodium channels producing a sustained late current (lqt3), mexiletine also shortens the qt interval in other forms of long qt syndrome including lqt1, lqt2 and lqt8. as the predominant action of mexiletine is on the early peak sodium current, there are theoretical reasons why drugs which preferentially suppress the late sodium current such as ranolazine may be more effective, although evidence that this is the case in practice is limited. amputation of the cervical sympathetic chain (left stellectomy). this therapy is typically reserved for lqts caused by jlns, but may be used as an add-on therapy to beta blockers in certain cases. in most cases, modern therapy favors icd implantation if beta blocker therapy fails. in patients considered at high risk of life-threatening arrhythmic events, icd implantation may be considered as a preventive step. arrhythmia termination arrhythmia termination involves stopping a life-threatening arrhythmia once it has already occurred. one effective form of arrhythmia termination in individuals with lqts is placement of an implantable cardioverter-defibrillator (icd). also, external defibrillation can be used to restore sinus rhythm. icds are commonly used in patients with fainting episodes despite beta blocker therapy, and in patients having experienced a cardiac arrest. as mentioned earlier, icds may be used also in patients considered at high risk of life-threatening arrhythmic events. with better knowledge of the genetics underlying lqts, more precise treatments hopefully will become available. outcomes genotype and qt interval duration are the strongest predictors of outcome for patients with lqts. these have been combined to create an externally validated risk score calculator, estimating a 5-year risk for each individual patient, which can help physicians to identify patients at the highest risk of life-threatening arrhythmic events. for people who experience cardiac arrest or fainting caused by lqts and who are untreated, the risk of death within 15 years is around 50%. with careful treatment this decreases to less than 1% over 20 years. those who exhibit symptoms before the age of 18 are more likely to experience a cardiac arrest. epidemiology inherited lqts is estimated to affect between one in 2,500 and 7,000 people. history the first documented case of lqts was described in leipzig by meissner in 1856, when a deaf girl died after her teacher yelled at her. soon after being notified, the girl's parents reported that her older brother, also deaf, had previously died after a terrible fright. this was several decades before the ecg was invented, but is likely the first described case of jervell and lange-nielsen syndrome. in 1957, the first case documented by ecg was described by anton jervell and fred lange-nielsen, working in tønsberg, norway. italian pediatrician cesarino romano, in 1963, and irish pediatrician owen conor ward, in 1964, separately described the more common variant of lqts with normal hearing, later called romano-ward syndrome. the establishment of the international long-qt syndrome registry in 1979 allowed numerous pedigrees to be evaluated in a comprehensive manner. this helped in detecting many of the numerous genes involved. transgenic animal models of the lqts helped define the roles of various genes and hormones involved, and recently experimental pharmacological therapies to normalize the abnormal repolarization in animals were published.