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.
About 20 percent of dofetilide is metabolized in the liver via the CYP3A4 isoenzyme of the cytochrome P450 enzyme system. Drugs that interfere with the activity of the CYP3A4 isoenzyme can increase serum dofetilide levels. If the renal cation exchange system is interfered with (as with the medications listed above), a larger percentage of dofetilide is cleared via the CYP3A4 isoenzyme system. History
After its initial US FDA approval, due to the pro-arrhythmic potential it was only made available to hospitals and prescribers that had received education and undergone specific training in the risks of treatment with dofetilide; however, this restriction was subsequently removed in 2016. See also
Antiarrhythmic agents
Cardiac action potential
Electrocardiogram


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