Long-term stability of atrial sensing in implantable cardioverter-defibrillators with floating atrial dipole leads

Abstract Introduction To maintain the advantages of having atrial sensing without the need to implant an additional lead, a single-lead ICD system with a floating atrial dipole (VDD DX ICD, Biotronik) with active fixation to the right ventricle has been developed. In this generation of ICDs, specially filtered atrial signs may be high enough to allow early detection of atrial arrhythmias and improve discrimination between atrial and ventricular tachycardias. However, maintaining reliable and stable atrial sensing via the floating dipole could be a concern regarding this technology. We aimed to determine the long-term stability of atrial sensing in patients (P) with this type of device. Methods All P implanted with ICDs with an active fixation DX lead at our centre between 2013 and 2021 were included. Atrial sensing and ventricular or supraventricular arrhythmic events were recorded during follow-up. We retrospectively analysed the atrial sensing evolution and compared it with a control group that had been implanted with a VDD pacemaker (PM). Results Seventy DX ICD P (82.9% males, age 69±14 years [between 19 and 86], 81.4% implanted as primary prevention) with > 1-year follow-up were included. The control group included 52P (age 82±6.3 years) who underwent PM implantation due to an advanced atrioventricular block. The mean P-wave amplitude at implantation was 4.85±2.44 mV in the DX ICD group and 1.54±0.89 mV in the VDD PM group. At one year after implantation, P-wave amplitude was 4.26±2.68 mV in the DX ICD group and 1.20±1.16 mV in the control group. From the control group, 7P (15,6%) lost atrial sensing after one year of follow-up, having their PM programmed as VVI after that. None of the P in the ICD group had lost atrial sensing in the same time period. After one year of follow-up, the P-wave amplitude had a mean reduction of 41.3% in the DX ICD group and of 65% in the control group (P=0.05). Conclusions Atrial signals can be reliably sensed by the floating dipole rings of a DX ICD in a long-term follow-up. This technology resulted in a higher stability of atrial sensing when compared with that obtained in P with a VDD PM. Additionally, a noteworthy number of P with a VDD PM lost atrial sensing, which did not happen in the group with the DX ICD.Results