Effectiveness of Remote Monitoring System to Detect ICD Lead Fractures

Backgrounds: Fracture of the Fidelis lead manufactured by Medtronic has been a serious concern in the management of the patients with implantable cardioverter defibrillator (ICD). The purpose of this study was to find the effective utilization of the remote monitoring system to detect the warning sign before inappropriate shocks. Methods and Results: We retrospectively studied the ICD data of the eight patients with fractured Fidelis leads. Oversensing events were recorded in all cases and inappropriate shocks were delivered in 5 cases within three days after the first oversensing episode. In 4 cases, the impedance of Fidelis lead had increased spontaneously around 400 ohms above the baseline level at the average of 5 days prior to the oversensing events. In three cases, the devices itself alerted the patients by sounds because the impedance had increased over 1000 ohms. However, two patients could not notice the alert and received unnecessary shocks. Conclusion: Spontaneous increase of the lead impedance can be the clue for the early detection of the fracture of Fidelis. Remote monitoring can be the effective tool to find it and prevent inappropriate shocks. For the better outcome, we request more flexible programming of the device so that we can detect the increase of the lead impedance under 1000 ohms (e.g. 400 »800).