Mortality Risk Hinted for Laser Extraction of Old Pacemaker, Defibrillator Leads

March 23, 2018

ORLANDO, Florida — Transvenous extraction of unused pacemaker or defibrillator leads poses a higher risk for death as an acute complication when it's performed by using a laser-based extraction sheath compared to a rotating cutting sheath, suggest a meta-analysis.

"We're not saying this is definitive, far from it," senior author, Byron K Lee, MD, University of California San Francisco (UCSF), told | Medscape Cardiology. "I think this warrants more research. It probably warrants a randomized controlled trial."

The study saw a more than ninefold mortality increase associated with procedures using one of the popular excimer laser lead-extraction sheaths compared with the other available sheath design, which uses a metal blade, across almost 9000 cases.

The meta-analysis, presented here at the American College of Cardiology (ACC) 2018 Annual Scientific Sessions by Sun Yong Lee, MD, also from UCSF, is based on reports published since 1998 covering transvenous lead extractions using either of the two technologies. They encompassed 7775 patients in 33 studies involving the laser sheath and 1094 patients in 14 studies involving the rotating cutting sheath.

"Wildly Underestimated" Risk

The current analysis is only one study, but it is "compelling" and should alert centers that do transvenous lead extractions to report more of their procedural data so the possible risks can be studied further, according to Raymond H Schaerf, MD.

The cardiothoracic surgeon with a high transvenous lead-extraction case volume, who isn't connected with Lee and colleagues' study, uses both sheath technologies at Providence St Joseph Medical Center, Burbank, California.

If the laser system's observed mortality increase is true, the field needs to know more about it, he said when interviewed. "If in fact people are having more problems with one set of tools than another set of tools, then it really is incumbent upon us to find out why."

Complications are a possibility with any lead extraction technique, "and the major articles that talk about the risk wildly underestimate what the risk is," Schaerf said.

"The way this data is presented is not an effective way to compare two different sets of extraction tools," according to Roger G Carrillo, MD, recently from the University of Miami Miller School of Medicine in Florida, who is widely published on the subject of lead extraction.

Carrillo commented on the meta-analysis to | Medscape Cardiology at the behest of Philips Spectranetics, which dominates the laser lead-extraction market with several popular dedicated excimer laser systems. The company said he is a compensated advisory board member.

According to the cardiothoracic surgeon, the different studies making up the meta-analysis used different methods and inconsistent entry criteria, with the potential for confounding.

For example, the patients in whom the rotating cutting sheath was used were less often female and less often had leads from an implantable defibrillator (ICD).

"Prior published data shows that female patients and patients with ICD leads are at highest risk of an adverse event," he wrote. "Therefore it makes sense that the laser group would show a higher adverse event rate."

He concluded, "In my opinion, a more standardized trial is needed to accurately compare mechanical vs laser extraction tools than what has been presented here."

Sources of Confounding?

Confounding isn't likely to account for all the increased risk observed in the analysis, according to Lee. But at least some is possible. Major potential sources of bias include varying criteria for selecting either device for a given patient and evolving operator experience over time.

With respect to patient selection, most centers that do a lot of lead extractions "are laser-first or rotating-sheath first," Lee said.  Some experienced operators use either type case-by-case, but many centers have only a rotating cutting system at their disposal. Meanwhile, those that have invested in one of the laser-sheath systems tend to prefer its use  as much as possible.

Lee acknowledges that the rotating-cutting-sheath experience overall has been more recent than many of the cases involving laser sheaths; the laser systems have been available longer. It's possible that outcomes in recent studies are confounded by operators who are more skilled, potentially magnifying the risk in the earlier years dominated by the laser systems.

Results Similar by Institutional Case Volume

In the analysis, lead extraction using the rotating cutting sheath (n = 1094) was associated with a procedural mortality of 0.09% compared with 0.85% for the laser sheaths (n = 7775), for a relative risk of 9.29 (95% CI, 1.29 - 66.87; P = .01) with the laser device.

The overall procedural success rate also favored the rotating cutting sheaths at 1.36 (95% CI, 1.09 - 1.69; P = .01).

The findings were similar when the analysis was restricted to medium- and high-volume transvenous lead extraction centers.

If the risk is greater with the laser systems, it may well be operator-dependent, especially with respect to depth of operator experience with the procedure, according to Schaerf.

Are the complications "coming from people who are very experienced users? Are they coming from people who are using it if another technique has failed? Or are they coming from people who maybe shouldn't be doing the procedure at all? That's the big question."

On the other hand, "we know that the guys at high-volume centers have complications, too," he noted. "Whether they are with the same types of cases that happen at the other centers is a whole other question."

Possible Mechanical Causes?

Schaerf pointed out that the potential for acute complications is twofold with the laser sheath compared with the rotating cutting sheath. The latter may be associated with vessel trauma due to mechanical pressure, whereas both mechanical and thermal trauma are possible with the laser system.

The latter is likely the basis for the increased risk seen for the laser system in the analysis, according to Lee.

Both sheath systems are designed to advance over old leads longitudinally, containing them as the sheath is advanced through the vessels around bends and turns. In the process they slice through any tissue adhering to the lead, the laser system by directing laser energy forward and the rotating cutting sheath with a blade.

But as the laser system advances through curves and corners, "you're shooting laser energy straight at the wall of the vessel. I think that weakens the wall and can lead to the tears you see with a laser system," Lee said.

Such vessel-wall tears most often occur in the superior vena cava (SVC) or at the SVC-atrial junction, he said. "That's what we see, at least, in the MAUDE database," based on a review of lead-extraction complications by type of extraction sheath that Lee and his colleagues reported at the November 2017 American Heart Association Scientific Sessions.

Byron K Lee discloses receiving consulting fees or honoraria from Biotronik; being an officer, director, trustee, or involved in another other fiduciary role for Cardionet; and receiving research grants from Medtronic. Sun Yong Lee  had no disclosures.

American College of Cardiology (ACC) 2018 Annual Scientific Sessions. Session 1142. Presented March 10, 2018.

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