When it comes to trouble in the med-tech industry it seems the old expression, “when it rains, it pours,” often applies. And the implantable cardioverter defibrillator (ICD) market seems no exception.
And considerable attention is being poured onto the companies making ICD leads — thin wires connecting the device to the heart — since Medtronic (Minneapolis) recalled its Sprint Fidelis defibrillation leads earlier this month because they may break inside the body (Medical Device Daily, Oct. 16, 2007).
According to Rick Wise, Bear Stearns med-tech analyst, the Riata 7 Fr ICD lead, made by St. Jude (St. Paul, Minnesota) has been under particular scrutiny and review as doctors and investors wonder if it might be recalled next.
However, during a Bear Stearns conference call Monday, Eric Fain, president of St. Jude’s cardiac rhythm management division, told listeners not to credit recent rumors that the Riata is in line for recall. Fain participated in the call with three prominent electrophysiologists (EPs).
Apparently the concern arose because the Fidelis leads, at 6.6 Fr in size, were the smallest on the market, and with that recall, the Riata 7 Fr leads are now the smallest.
The other major sector player, Boston Scientific (Natick, Massachusetts), has no lead smaller than 9 Fr.
Citing data from three large St. Jude registries on 121,000 implants, Fain reported 13 fractures, an overall rate of 0.011%, involving the Riata leads, which he noted is 20 times less than reported for Medtronic’s Fidelis.
Fain said that St. Jude considers the reliability of its Riata leads to be “quite good” and having the “highest reliability yet.”
Design differences are what separate the two leads, according to Fain.
In the Riata leads, he said, the coil conductor is central, with the cable conductors arranged symmetrically around the coil in order to provide mechanical protection. In contrast, an asymmetrical design is used in the Fidelis leads, with the coil at one side and the cable conductors on the other so they are not protected from outside mechanical forces, he said.
Direct welding is another important design difference, Fain said.
“At St. Jude we have a design rule that does not allow for any designs that would have direct welding of the cables to the electrodes,” Fain said, for two reasons: “The first, is that it’s known that direct welding can cause damage to the fine hair-like fibers that make up the cables. Secondly, the cables are made from different materials than the electrodes that they’ll be joined to and it’s also known that welding dissimilar materials can produce a weaker joint due to brittleness and cracking.”
Fain said Medtronic used a direct welding for its Fidelis leads, but for its previous Quattro leads used a similar crimping technique that St. Jude uses for Riata leads.
“Therefore as you can see there is significant difference between the Riata and Fidelis leads, and we believe that those differences are directly related to the performance differences ... in clinical use.”
While the Riata leads may not be related to the same fracture rates as the Fidelis, one study suggests that the Riata has a higher perforation rate.
However, that study was just a single-site experience and should be interpreted from that perspective, according to Jagmeet Singh, MD, director of the cardiac resynchronization therapy program at Massachusetts General Hospital and assistant professor of medicine at Harvard Medical School (both Boston).
“We looked at about 130 Riata leads and 111 Sprint Fidelis leads and we found that there was a higher perforation risk to the tune of 3.8% in the Riata lead side as opposed to 0% in the Sprint Fidelis lead,” Singh said during the call.
But because the study only examined the 8 Fr version of the Riata leads and not the 7 Fr version, “we’re not really comparing apples with apples,” Singh acknowledged.
St. Jude cites a 0.086% perforation rate in patients implanted with its Riata leads, Fain said. Looking specifically at the 7 Fr version of the leads, he noted a perforation rate of 0.16% out of about 35,000 patients.
“Both of these rates are low and are at or below the low end of what’s been reported in the literature for defibrillator lead perforations,” Fain said.
He highlighted three main factors contributing to lead perforation: lead design; patient-specific factors including the patient’s medical condition and what medications they are using; and implant technique.
All three physicians agreed with Fain during the call that these three factors — and implantation technique in particular — play a large part in lead perforation.
Roger Freedman, MD, director of clinical cardiology and a professor of medicine in the division of cardiology at the University ofUtah Health Sciences Center (Salt Lake City), said that he has implanted about 150 Riata leads and recalls only one perforation with an 8 Fr Riata lead, about three years ago.
Freedman, also a member of St. Jude’s independent leads medical advisory board, said it has not implanted as many Fidelis leads, but does lead extractions on a regional level, by referral.
“This spring I had a cluster of maybe three Fidelis leads that were sent to me because of fracture and over-sensing and complications that required extraction,” he said.
Likewise, Raffael Corbesiero, MD, vice chair of cardiovascular medicine, section chief of electrophysiology and pacing, and chair of the Electromechanical Therapy Institute, at the Deborah Heart & Lung Center (Brown Mills, New Jersey), also does lead extractions on a referral basis.
Corbesiero said he began seeing referrals for extractions of the Fidelis leads some four to six months ago and that most of those referring physicians were switching back to Medtronic Quattro leads.
Singh, on the other hand, said that though he began cutting back his use of Fidelis leads when problems first arose, he continued to use it until about two weeks before the recall “because there are often times situations when you really need a thin lead.”
The three EPs agreed that, going forward, they would not have any reluctance using the thinner leads, such as the Riata. They also agreed that St. Jude — as the only manufacturer with a 7 Fr ICD lead — would most likely gain market share as a result of the Medtronic recall, and they expect St. Jude to sell more systems (generator and lead) because physicians tend to avoid mixing and matching.
“We left the call encouraged that Riata is performing well... better than many had thought... and that [St. Jude’s] share could benefit from the recent safety concerns,” Wise wrote in a report released as a wrap-up to Monday’s call.