Sporadic high impedance values without other anomalies have been recently described by remote monitoring for hybrid cardiac implantable electronic device (CIED) systems. The clinical significance and related hazard of this phenomenon are not fully understood.
To describe prevalence, management and outcomes associated with hybrid implantable cardioverter defibrillator (ICD) systems.
We collected data about patients with sporadic high lead impedance alert on remote monitoring, implanted between January 2015 and December 2019 with hybrid ICD system. Pacing thresholds, sensing and impedance values, alongside temporal pattern of impedance values, were collected by remote monitoring, at implantation and during in-office visit.
Among 92 patients receiving hybrid ICDs, 15 (16.3%) had high impedance alert at remote monitoring, 14 Boston Scientific and 1 St. Jude Medical ICD canisters paired with Medtronic or Biotronik DF-1 leads. Four patients had a cardiac resynchronization therapy defibrillator (CRT-D), 7 patients had dual-chamber ICD and 4 patients single-chamber ICD. Three patients presented high atrial lead impedance, 7 patients high right ventricular lead impedance, 1 patient high left ventricular impedance and 2 patients high shock impedance values. All patients were followed-up via remote monitoring and sporadic high impedance values were not associated with adverse outcome or need of revision in all but one patient that presented continuously increasing pacing thresholds due to lead microfracture.
In absence of clear signs of lead fracture or connection issues, sporadic high pacing and shock impedance in hybrid implantable defibrillator systems can be safely managed through close follow-up.

Copyright © 2021. Published by Elsevier Inc.
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