A case of biventricular pacing with a spike on T-wave caused by the algorithm maintaining biventricular pacing rate

Cardiac-resynchronization therapy (CRT) improves the cardiac function of patients with left ventricular (LV) dyssynchrony. Maintenance of the biventricular pacing rate is very important in managing the hemodynamics in patients implanted with CRT devices. A low biventricular pacing rate, for example, in cases with atrial fibrillation or rapid intrinsic atrioventricular (AV) conduction, decreases the benefits of CRT. The LUMAX HF-T 540 device series (BIOTRONIK, Berlin, Germany) has a LV-triggered pace algorithm, which allows biventicular pacing rates to be maintained even during rapid intrinsic rhythms caused by shortened AV conduction and/or premature ventricular contraction (PVC) occurring in the right ventricle. We encountered a case of CRT device implantation with a defibrillator wherein this triggered pace algorithm caused a spike on T-wave due to T-wave oversensing. By remote monitoring, we were also able to determine that the T-wave oversensing was due to a PVC. The LUMAX 540 series allows for changes in the sensing threshold and filter settings of the device, which facilitated the elimination of T-wave oversensing in this case.