Limited Utility of Exercise-Stress Testing to Prevent T-Wave Oversensing in Pediatric Internal Cardioverter Defibrillator Recipients

Background: Inappropriate internal cardioverter defibrillator (ICD) therapies may result from T-wave oversensing (TWOS) during exertion in children. The aim of this study was to evaluate the utility of an exercise treadmill test to predict inappropriate ICD therapies secondary to TWOS.

Methods: Eligible pediatric ICD recipients underwent exercise-stress testing with concomitant evaluation of all intracardiac electrograms. Double counting at a programmed sensitivity of 0.3 mV was considered indicative of TWOS. Patients were prospectively followed for 2 years and censored at either the development of an inappropriate ICD therapy secondary to TWOS or at the time of ICD revision.

Results: Nineteen patients (age: 13.8 ± 3.2 years) underwent exercise testing (median time from ICD implant: 1.5 years, range 2–4.3 years). Two patients were identified with TWOS during the stress test and had a clinically inappropriate ICD discharge within 2 weeks despite a sensitivity adjustment to 0.6 mV. One individual had an inappropriate ICD discharge from TWOS 11 months following an initial uneventful exercise-stress test.

Conclusions: Inappropriate ICD therapies from TWOS relate to a reduction in the intrinsic R wave or augmentation of the T wave during exertion. While intracardiac electrogram assessment during stress testing may aid in the early recognition of TWOS, it did not absolutely translate to a reduction in the incidence of inappropriate ICD shocks. (PACE 2011; 34:436–442)