QT syndrome, long (LQTS)

QT syndrome, long (LQTS): A genetic (inherited) condition that predisposes individuals to irregular heartbeats (arrhythmias), fainting spells and sudden death. The irregular heartbeats are typically brought on by stress or vigorous activity. LQTS is often symptomless and undiagnosed. However, it is well known as a cause of sudden cardiac death in young, apparently healthy people, most notably competitive athletes. The QT (in the long QT syndrome) refers to an interval in the electrocardiogram (ECG or EKG).