Short QT syndrome is a new genetic disorder associated with familial atrial 
fibrillation and/or sudden death or syncope. To date, different mutations in 
genes encoding for cardiac ion channels (KCNH2, KCNQ1, and KCNJ2) have been 
identified to cause the short QT syndrome. The mutations lead to a gain of 
function of the affected current (IKr, IKs, and IK1). The phenotype is 
characterized by a shortened QT interval<335 ms after correction for heart rate 
at rates<80 beats/min. Furthermore, the QT interval poorly adapts to heart rate. 
Patients exhibit shortened atrial and ventricular effective refractory periods 
and, in the majority, inducibility of ventricular fibrillation. Death occurs 
already in newborns. Therapy of choice seems to be the implantable cardioverter 
defibrillator because of the high incidence of sudden death. Pharmacological 
treatment has been studied and it could be demonstrated, that some mutant 
currents may be insufficiently suppressed by drugs targeted to block the 
specific current such as, e.g., sotalol or ibutilide in patients with a mutation 
in the IKr-coding gene KCNH2 (HERG). Quinidine proved to be efficient in 
prolonging the QT interval and normalizing the effective refractory periods in 
some patients.