Transient repolarization instability following the initiation of cardiac resynchronization therapy.

Aims: Cardiac resynchronization therapy (CRT) may cause changes in ventricular repolarization (VR), particularly in the initial phase of treatment. This study investigated the effect of CRT cessation and re-initiation on parameters of VR duration and heterogeneity at different paced heart rates.

Methods: Cardiac resynchronization therapy was inactivated for 2 weeks in 16 treatment responders to CRT.