As reported in JACC: Clinical Electrophysiology, Dr. Petr Neuzil of Na Homolce Hospital in Prague and colleagues retrieved implanted Nanostim LPs from 34 patients (mean age, 78; 63% men) whose devices were implanted in 2012-2014. The primary indication for retrieval was battery failure (85%), followed by device upgrade (12%) and elevation in pacing threshold (3%).
The cohort was divided into two groups, based on fluoroscopic imaging: those with and without remarkable swinging movement (SM) of the LP docking button (25 vs. nine, respectively).
The LP retrieval success rate was 85% overall. The success rate was significantly higher in the SM than in the no-SM group (100% vs. 44%), and the mean fluoroscopy time during the retrieval procedure was shorter in the SM group (12.7 min vs. 45.6 min).
New leadless devices were implanted in 27 patients immediately after LP retrieval. No procedure-related adverse events occurred.
The authors list several limitations, including: a single-center, nonrandomized observational study; unclear why tissue may adhere to an implanted LP and unclear how infection would affect retrieval; learning curve for the procedure may have influenced the success rate; and need for long-term follow-up of reimplanted LP devices.
Two experts commented by email to Reuters Health.
Dr. Daniel Wang, Director of Cardiac Electrophysiology at White Plains Hospital in New York, said, "This is a relatively new technology, and the optimal management strategy for when the battery depletes is still uncertain. There is limited experience with this, as the majority of patients with leadless pacemakers are still on their first device and have not yet reached battery depletion."
"The mainstay option currently would be to implant a new LP and program off the old LP, leaving it in place," he said. "Retrieving the old LP just before implanting the new one would be a more elegant option - if it can be done safely and effectively. It would avoid potential mechanical inference between the pacemakers, and it would avoid leaving unnecessary hardware in the heart."
That said, he noted some caveats: "The study describes retrieval of an earlier make and model of leadless pacemaker - St. Jude Nanostim - whose implantation has been halted worldwide. It is not approved by the U.S. Food and Drug Administration. The only FDA-approved leadless pacemaker is the Medtronic Micra, which has a shorter length and different construction than the Nanostim."
"Therefore," he said, "the findings of the study cannot be directly applied to our patients in the U.S. with the Micra. We still await long-term data on feasibility and safety of retrieval of (that device)."
"A potentially even more appealing solution," he added, "is rechargeable battery technology, already available for other implanted devices such as neurostimulators. It would be a welcome next step for pacemakers."
Cardiac electrophysiologist Dr. Pedram Kazemian, Medical Director of Clinical Research at Deborah Heart and Lung Center in Browns Mills, New Jersey, commented, "Since these devices only pace the right ventricle, they are mostly useful for patients with chronic atrial fibrillation, who tend to be older. At the end of the life of battery, one can add another device next to previous one and gain another 10 years of function. For most of this patient population, 20 years is all is needed, given their life expectancy."
"Extraction of leadless pacemakers is not something we would like to do and in fact they were developed in the first place so that extraction would not be required," he noted. "With that being said, there are rare cases when we may have to extract them."
"Snaring a moving object that has a diameter of 5 mm in a beating heart that has other vital structures in the vicinity... with a wire that is controlled by a push-pull mechanism three feet away, without direct visualization, is a risky procedure," he said.
"The authors did not report what percentage of patients sustained tricuspid valve damage as a result of inadvertent entanglement with snare, for example," he said. "Long-term stability and electrical threshold of the newly implanted leadless pacemaker post-explantation is also unknown."
Further, he added, "We should always reassess the indication for pacemakers at the time of re-implantation. Not surprisingly, sometimes we don't need to re-implant the device if the indication has resolved."
Dr. Neuzil and principal author Dr. Vivek Reddy did not respond to requests for a comment. Both have received grant support from Abbott, manufacturer of the Nanostim leadless pacemaker used in the trial.
By Marilynn Larkin
SOURCE: https://bit.ly/3lX6Qpj JACC: Clinical Electrophysiology, online August 26, 2020.
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