Assessing the True Risk of QT Prolongation
The QT interval is the interval on an EKG that represents the time it takes for the heart’s ventricles to depolarize and repolarize. Long QT syndrome, caused by a prolonged QT interval, can be either congenital or acquired. Most acquired cases are caused by either electrolyte imbalances or medications. The most accurate way to diagnose long QT syndrome is by measuring the QT interval and correcting for heart rate, termed the QTc interval. Not much is known about the incidence of acquired long QT syndrome, but the prevalence of congenital cases has been estimated at 1 in 2,000 live births.