We will start with Long QT syndrome (Definition and Epidemiology):
Inherited long QT syndrome (LQTS) is characterized by a prolonged QT interval, syncope, and sudden cardiac death due to ventricular tachyarrhythmias, typically torsades de pointes (TdP).
LQTS has variable penetrance, and the estimated prevalence of clinically overt disease is approximately 1:2000 subjects.
Symptomatic patients without therapy have a high mortality rate, 21% within 1 year from the first syncope, but, with proper treatment, mortality is now ≈1% during a 15-year follow-up.
