from the Heart Rhythm Society’s annual scientific sessions in Boston
Ever since Medtronic announced in October 2007 that the Fidelis defribrillator leads they had been making were being pulled off the market because of their tendency to fracture and fail physicians and patients have wondered how much of a risk they poses to the people who already have the leads implanted and what should be done about them.The latest news from one of the biggest annual gatherings of cardiologists who specialize in placing and removing implanted defibrillators was a mix of both bad and good news.
The bad news was that by at least some measures the failure rate has been getting worse. For example, in one of the largest databases of Fidelis leads that’s not maintained byMedtronic, a record on 6,215 Canadian patients
who received the leads, the failure rate during the most recent 12 months was 3%, up from a rate of about 1%/yr during the first 2 years of follow-up, Dr. Andrew D. Krahn said at the meeting.
A similar pattern of accelerating failures occurred in a smaller series of 604 patients who received leads at the University of Vermont. Those patients showed a failure rate of about 5% during the most recent, fourth year, and as in Canada a 3% rate during the third year of follow-up and about a 1% failure rate/year during the first 2 years.
Part of the good news is that few patients have died as a consequence of these failures. According to data released by Medtronic in March, 13 of the roughly 268,000 patients who received Fidelis leads worldwide had died, and in four cases mortality occurred when the lead was removed. The worst adverse effect most patients with failed leads get is an inappropriate shock, and not everyone even gets that. In fact, in Canada the rate of inappropriate shocks from failed leads has recently dropped, said Dr. Krahn, a cardiologist and electrophysiologist at the University of Western Ontario in London. “Shock rates are way down, making everyone’s life a lot simpler,” he said.
Another piece of good news was that when a Fidelis lead fails and has to be removed it may usually be a fairly benign process. Another report at the meeting presented the combined experience from four U.S. medical centers in removing Fidelis leads from 273 patients during 2005-2009. The extractions produced no major complications (including no deaths) and three minor complications, for a minor complication rate of 1%. This experience contrasts with a historic major complication rate of 1%-7% for removal of all sorts of defibrillator and pacemaker leads cited by Medtronic in 2007 when it issued its warning about the Fidelis lead.
Fidelis leads may be failing at high rates, but at least they seem relatively easy to remove when necesssary, concluded Dr. Melanie Maytin, an electrophysiologist at Brigham and Women’s Hospital in Boston who presented the data on the 273 Fidelis-lead extractions.
—Mitchel Zoler (on Twitter @mitchelzoler)