Short QT Syndrome

 

Gene affected: HERG (KCNH2) which affects the potassium channel. Several mutations have been identified.

 

Clinical features:

(1) family history of sudden death which may occur at any age, including during infancy

(2) absence of structural heart disease

(3) syncope

 

ECG and electrophysiologic features:

(1) short QT interval (QTc < 360 ms according to Schimpf et al; <= 300 ms according to Gaita et al)

(2) atrial fibrillation and/or ventricular tachyarrhythmias

(3) very short ventricular refractory periods on electrophysiologic studies

(4) increased dispersion of repolarization

(5) ability to induce malignant ventricular arrhythmias during electrophysiologic studies

 

Therapy:

(1) ICD placement in an adult

(2) drug therapy with quinidine or disopyramide