Potential role of home monitoring to reduce inappropriate shocks in implantable cardioverter-defibrillator patients due to lead failure

Aims Lead dysfunctions in implantable cardioverter-defibrillator (ICD) patients can lead to inappropriate shocks or even complete loss of function of the device. Home monitoring (HM) systems are capable of daily data transmissions regarding the device and the lead integrity as well as information concerning anti-arrhythmic therapies. We therefore analysed the data from the Biotronik HM system whether it enables physicians to react quickly on serious ICD malfunctions and to avoid inappropriate shocks. Methods and results Fifty-four patients who had to undergo resurgery due to malfunctions of the ICD lead were included. Eleven of them were on HM interrogating the device every night at 3 am. If any adverse event was detected, a fax alert was sent to the clinic and the patients were asked for in-hospital ICD interrogation. The rate of inappropriate shocks and symptomatic pacemaker inhibition due to oversensing was compared with the 43 patients without remote surveillance. HM sent alert messages in 91% of all incidents. All lead failures became obvious because of oversensing of high frequency artefacts. Only in 18%, changes in the pacing impedance were noticed, in all cases preceded by oversensing. Eighty per cent of the patients were asymptomatic at the first onset of oversensing. Only one patient suffered an inappropriate shock as first manifestation of lead failure. Compared with the patients without HM, inappropriate shocks occurred in 27.3% in the HM group vs. 46.5% (P = n.s.). This trend gains statistical significance, if the compound endpoint of symptomatic lead failure consisting of inappropriate shocks and symptomatic pacemaker inhibition due to oversensing is focused: 27.3% event in the HM group vs. 53.4% in the group without HM (P = 0.04). Event messages were despatched in a mean of 54 days after the last ICD interrogation and 56 days before next scheduled visit. Thus, 56 days of reaction time are gained to avoid adverse events. Conclusion In 91% of all lead-related ICD complications, the diagnosis could be established correctly by an alert of the HM system. Mostly, the first incident sent was oversensing of artefacts, falsely detected as ventricular fibrillation-the VF zone. The automatic HM surveillance system enables physicians to detect severe lead problems early and to react quickly; thus, it might have a potential to avoid inappropriate shocks due to lead failure and T-wave oversensing.