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BOSTON -- Lead wires implanted for conduction system pacing have thus far been feasible to remove despite their more challenging characteristics, a multicenter study showed.

The leads were removed with manual traction alone in 91% of the 341 patients, with a rate of 90% for leads attached to the His bundle and 92% for those placed in the left bundle branch area, Pugazhendhi Vijayaraman, MD, of the Geisinger Heart Institute in Wilkes Barre, Pennsylvania, reported at the .

Another 8% of cases needed mechanical extraction, 2% required laser instruments, and 1% were done with femoral tools.

Removal was a complete success in 99% of cases, defined by full removal of targeted leads and all lead material from the vascular space without any permanently disabling complication or death. Vijayaraman called the complication rate low in this cohort.

However, the mean lead dwell time was 22 months, and even shorter on average for the leads with the newer left bundle branch area pacing approach (52% <6 months). "The shorter dwell time of left bundle branch area pacing lead does not allow us to predict the outcome of removal of older left bundle branch area pacing leads," Vijayaraman cautioned at the late-breaking clinical trial session.

Conduction system pacing has been increasingly utilized for both treatment of bradycardia and cardiac resynchronization therapy. "Despite significant increase in the adoption of using both the lumenless leads and more recently the stylet-driven leads," Vijayaraman noted, "there's still concern regarding the feasibility and safety of extraction of these leads because of where they are located -- the His bundle pacing lead in a more fibrous membranous septum and the conduction left bundle branch pacing lead more in the deep interventricular septum."

Lead architecture and the potential for leads breaking at their septal insertion point or damaging the tricuspid valve are also worries, added HRS study discussant Matthew Zipse, MD, of the University of Colorado Anschutz Medical Campus in Aurora. "Most of us cut our teeth extracting stylet-driven leads, and so this lumenless lead architecture may present a bit of an unknown."

The conduction system pacing leads are strong but "not indestructible, particularly if this inner conductor cable is compromised," he noted, pointing to a case he treated in which a "very old lumenless lead, which really fully unraveled, requiring piecemeal removal of lead fragments. So I think we'll have to be mindful of this potential when extracting older lumenless leads."

The retrospective TECSPAM (Transvenous Extraction of Conduction System Pacing leads: An International Multicenter) study included 341 patients undergoing extraction of conduction system pacing leads at 10 international centers. Among them, 224 had His bundle pacing leads and 117 had left bundle branch area pacing leads. All were removed for class I or II indications under the 2017 HRS consensus document criteria.

"However, only 6% of the leads in this study were stylet-driven leads," Zipse cautioned, "so I don't think you can make many conclusions about those leads. All the left bundle leads were relatively young and I think VSDs [ventricular septal defects] are going to be unlikely. But it remains unclear whether older lead tips will break. And I'll say in conclusion that the last thing is that there's value in countertraction and left bundle pacing lead as dwell times mature, we should still have a low threshold to use extraction sheets, rather than relying just on traction and pulling harder, which otherwise could risk venous tear and tricuspid damage."

No patient with His bundle pacing lead had new severe tricuspid regurgitation that was suggestive of valve damage from lead removal. Two patients had residual fragments left behind. One case of transient atrioventricular block occurred.

Another point to note was that the operators involved in the study were experts in lead extraction, noted HRS session moderator Sana Al-Khatib, MD, MHS, of Duke University Medical Center in Durham, North Carolina.

"Probably from a society perspective," Vijayaraman suggested, "we should create a registry for all the conduction system pacing leads, to assess the failure rates and the functionality of the leads and also the extractability of those leads, because now the industry is providing us with newer defibrillator leads with similar functionality. And that's another scary part that we have to be aware of when we are proactively collecting data so that we can course correct if we ever have to."

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