Short QT syndrome is an inheritable primary electrical disease of the heart that 
was discovered in 1999. The disorder is characterized by an abnormally short QT 
interval (<300 ms) and a propensity to atrial fibrillation, sudden cardiac death 
or both. As in the case of long QT syndrome, more than one relevant genetic 
mutation has been identified that can lead to a short QT interval on 
electrocardiography; so far two have been identified. Shortening of the 
effective refractory period combined with increased dispersion of repolarization 
is the likely substrate for re-entry and life-threatening tachyarrhythmias. Thus 
far, 22 people have been classified as having short QT syndrome: 15 from the 
actual measurement of a short QT interval on electrocardiograms and 7 by history 
after they died from sudden cardiac death. Several cases, especially among 
children, have probably been overlooked, since the shortness of the QT interval 
becomes apparent only at heart rates less than 80 beats/min. The best form of 
treatment is still unknown, but prevention of atrial fibrillation has been 
accomplished by propafenone. Implantation of an implantable cardioverter 
defibrillator is recommended for prevention of sudden cardiac death.