Short QT syndrome (SQTS)

This rare condition is similar to but distinct from long QT syndrome (LQTS). As the name suggests the QT interval in carriers is shorter than in normal people. This means that the heart takes a shorter time to repolarise or reset itself,making it prone to ventricular arrhythmias. There is also an increased risk of a less dangerous arrhythmia from the top chambers of the heart (the atria) called atrial fibrillation. This is an irregular and rapid heart rhythm that may go unnoticed or causes breathlessness and palpitations. As in LQTS, potassium channel genes are affected but instead of allowing less potassium through they allow through too much too quickly.

What are the symptoms?

Palpitations, blackouts and cardiac arrest.

Are there any physical signs?

There are no physical signs usually except if there is atrial fibrillation when an irregular rapid pulse may be felt by the doctor.

How is it diagnosed?

The ECG abnormalities are usually detected either on a standard ECG or a 24-hour Holter. An electrophysiological study may also help the doctor make a diagnosis. Genetic testing may find a potassium channel mutation in affected members of a family that may then also be found in other relatives.

Treatment and advice

If you have short QT syndrome (SQTS) it is likely that an implantable cardioverter defibrillator (ICD) will need to be fitted in order to treat dangerous arrhythmias. Quinidine has been used in some patients but it is unclear whether it is safe to rely on medication alone. Tablets may also be used to treat atrial fibrillation.