Failure of the active-fixation mechanism during removal of active-fixation pacing leads.

BACKGROUND: Active-fixation pacing leads are being widely employed due to their theoretical advantages when compared with traditional passive-fixation leads: easy fixation and reposition, possible deployment in alternative pacing sites, lower rates of dislodgment, and chronic removability. However, the behavior of the active-fixation mechanism during lead removal has not been yet systematically studied and may have important clinical implications.
OBJECTIVE: To evaluate if the active-fixation mechanism was still working properly in pacing leads that were removed due to different causes.
METHODS: Thirty-one consecutive patients undergoing active-fixation lead removal (40 leads) were studied. Before lead removal, the helix was retracted using the appropriate tool, and fluoroscopy signs were evaluated. After removal, the helix status was examined, and the active-fixation mechanism was once again retested when possible.
RESULTS: In nine of 40 leads (22.5%), the helix remained extended after lead removal in spite of having applied the number of rotations recommended by the manufacturer with the clip-on tool. There was no linear relationship between lead longevity and the presence of an extended helix after lead removal. However, failure of the active-fixation mechanism was more frequent among leads implanted <1 year before versus >1 year before (OR 6.8, 95% CI 1.1-42.7, P = 0.043). In 38% of patients with failure of the active-fixation mechanism, a previous lead reposition had been attempted before lead removal due to significant pacing threshold rise.
CONCLUSIONS: In our series, the active-fixation mechanism failed in up to 22.5% of explanted leads. This may have important clinical implications during active-fixation lead removal and reposition. ©2011, The Authors. Journal compilation ©2011 Wiley Periodicals, Inc.