Long QT syndrome is in most cases, a hereditary condition, and it may be familial accumulation of the condition. In some cases, we are combined congenital deafness (Jervell and Lange-Nielsen syndrome). Other forms (e.g. Romano-Ward syndrome) have an accompanying hearing loss.
Long QT syndrome can also occur without the existence of a hereditary disposition (acquired condition). Generally, this is due to the use of drugs that affect heart rate. People who for whatever reason, very slow pulse, may be susceptible to this form of acquired long QT syndrome.
The danger with a prolonged QT segment is that predispose to seizures with a dangerous heart rhythm ( ventricular tachycardia, torsades de pointes). Such attacks can heal by themselves, but they can also cause cardiac arrest and death.
What is the prognosis?
Long QT syndrome can lead to sudden cardiac death in otherwise healthy young individuals. Overall, it appears that about. 6% of those with this condition have died at 40 years of age.
Experts believe that most episodes of heart attack go by itself and that only 4-5% of attacks leading to cardiac arrest and death.
Treatment with beta-blocker provides decent prognosis for most people. The prognosis after the implanted defibrillator is very good.