In this patient, oversensing of the T-wave was present after a spontaneous ventricular event but also after a paced ventricular event.  It was not responsible for a significant drop in the percentage of biventricular pacing. The device recorded a large number of premature ventricular contractions corresponding to the T-wave oversensing episodes.

Oversensing of the T-wave can in some cases promote the absence of biventricular pacing. The T-wave is considered as a ventricular premature contraction, which causes a prolongation of the PVARP if the “response to a PVC” algorithm is turned ON. The next sinus P-wave falls into the PVARP, and therefore does not trigger a new AV delay, and the phenomenon perpetuates as shown in the previous case.