Implantable cardioverter defibrillator replacement guided by T wave safety margin in a short QT syndrome patient.

We report implantable cardioverter defibrillator (ICD) generator replacement guided by T wave safety margin (TWSM) in a short QT syndrome patient with T wave oversensing (TWOS). During the procedure of generator replacement, the feature of ventricular sensing in four different ICDs was compared in the patient. The four ICDs showed different R and T wave amplitudes. Though R/T ratio is not the highest, Vitality ICD showed the highest TWSM and was implanted as replacing generator. During 20-month follow-up, the patient has been symptom-free with no T-wave oversensing episode. This case illustrates a method to evaluate the risk of TWOS before ICD implantation in patients with high risk of TWOS.