Secondary causes of a short QT interval such as drugs and electrolyte disturbances should be ruled out before embarking on an evaluation as to whether the patient has one of the short QT syndrome variants. Recent diagnostic criteria have been published out of the Arrhythmia Research Laboratory at the University of Ottawa Heart Institute from Drs. Michael H Gollob and Jason D Roberts.^[1]

The Short QT Syndrome diagnostic criteria is based on a point system as follows:

• QTc in milliseconds

<370 = 1 point

<350 = 2 points

<330 = 3 points

• J point – T peak interval in milliseconds

<120 = 1 point

• Clinical History

Sudden cardiac arrest = 2 points

Polymorphic VT or VF = 2 points

Unexplained syncope = 1 point

Atrial fibrillation = 1 point

• Family History

1st or 2nd degree relative with SQTS = 2 points

1st or 2nd degree relative with sudden death = 1 point

Sudden infant death syndrome = 1 point

• Genotype

Genotype positive = 2 points

Mutation of undetermined significance in a culprit gene = 1 point

The points are summed and interpreted as follows:

• > or equal to 4 points: High-probability of SQTS
• 3 Points: Intermediate probability of SQTS
• 2 points or less: Low probability of SQTS