Gradually Increasing Pacing Impedances with Normal Sensing Values in Pacemaker and Defibrillation Leads: A Watchful Waiting Strategy.

Background: The increasing prevalence of cardiac implantable electronic devices (CIEDs) has led to greater data collection, including pacing impedance, a key measure of lead integrity and electrical function. While acute impedance changes may signal lead fractures or insulation defects, gradual increases are often linked to tissue-interface calcification. The optimal management of patients with progressively rising impedance remains uncertain.

Objective: To assess the prevalence, clinical consequences, and management strategies for CIED leads showing a gradual increase in pacing impedance above 1200 ohms.

Methods: We conducted a single-center retrospective cohort study of 59 patients (42 with an implantable cardioverter defibrillator (ICD) and 17 with a pacemaker) over a median follow-up of 9.2 years [range: 2.8-18.5]. Data on patient demographics, device characteristics, and outcomes associated with elevated impedance were analyzed. Impedance values, intracardiac signals, and pacing thresholds were assessed at baseline and every six months up to 18 years.

Results: Among ICD patients, 33 of 42 leads (78.6%) were preserved, while 9 were replaced (5 prophylactically, 2 due to oversensing, and 2 for threshold issues). In pacemaker patients, 12 of 17 leads (70.6%) were preserved, with 5 replacements (4 prophylactic, 1 for threshold issues).

Conclusion: A watchful waiting strategy appears safe for patients without sensing or threshold concerns and in the absence of a pacing indication. A patient-centered approach should guide the management of gradual impedance increases in CIED leads.