Shorting Problem with Guidant ICD Device Causes Stir in EP Community
Shorting Problem with Guidant ICD Device Causes Stir in EP Community
May 27, 2005
MedScape Today (www.medscape.com)
Original Article Here
Guidant Corporation (Indianapolis, Indiana) sent a letter to physicians this week informing them about a potential shorting defect in certain models of the company's PRIZM 2 DR implantable cardioverter defibrillator (ICD) that in rare cases could render the devices incapable of delivering a life-saving shock. The letter was sent after an article in the New York Times on Tuesday revealed that a 21-year-old college student from Minnesota had died as a result of the defect. The student, who was diagnosed with hypertrophic cardiomyopathy, was implanted with a PRIZM 2 DR in 2001. He suffered a cardiac arrest 2 months ago and died after his ICD failed to fire.
In its letter, Guidant seeks to reassure physicians that the shorting phenomenon
is extremely rare, and the company recommends against immediate replacement
of the implants. Instead, the letter advises doctors only to continue normal
monitoring of patients who have the devices. However, not all physicians agree
with these recommendations. In fact, the company has been sharply criticized
for failing to notify doctors earlier of the problem. The fallout has led some
in the electrophysiology (EP) community to call for the establishment of definitive
guidelines governing disclosure of rare product defects since such problems
represent a gray area in postmarket device monitoring that currently falls outside
the realm of product recalls and FDA actions.
Defect First Identified in 2002
Over a period of 2 years, between November 2000 and November 2002, Guidant
made and sold 37,000 of the affected devices, and 24,000 patients worldwide
still have the implants. To date, the company has identified 26 cases of device
failure due to the defect (an overall failure rate of 0.07%), and no other deaths
have been reported.
The company first detected the shorting problem early in 2002, after a few defective devices had been explanted from patients and returned to the company for analysis. Guidant subsequently made manufacturing and device design changes to correct the defect and began shipping the revised models in November 2002. Although the corrective modifications were reported to the FDA, no notification was made directly to physicians at that time, Richard Fogoros, MD, Medical Advisor in Guidant's R&D department, told Medscape CRM.
The shorting defect is related to the design of the header where the leads are plugged in, a design that was unique to these particular device models, Fogoros explained. Under certain circumstances (and, he pointed out, there are actually 4 things that need to go wrong for this to happen), the wires can short out when the ICD is preparing to deliver a shock. As a result, the device becomes nonfunctional and the shock is ineffective.
This event is extremely rare, Fogoros said, occurring at a rate of only 0.002% per month, regardless of the age of the device. And comparatively, it is a much smaller risk than the industry average rate of ICD device failure due to random component failure, which is 0.01% per month. According to Fogoros, there is no chance that this problem could show up in any other models of Guidant ICDs on the market, as the flawed header design was unique to that particular model of ICD and has not been used since.
What is at issue for many doctors is Guidant's decision not to inform them of the device flaw until 3 years after it was initially identified. Fogoros told Medscape CRM that the company had no plans to directly communicate with doctors about the problem until recent publicity surrounding the college student's death brought it to the forefront (in addition to the New York Times article, the young man's case reportedly has been submitted for publication in an upcoming issue of the medical journal Heart Rhythm).
But Fogoros vigorously defended the company's course of action. "The risk of failure [with this device] is an order of magnitude less than one would expect from random component failure." Thus, replacing the device would not yield any benefits statistically. In fact, he said, "the FDA was made aware of each event as it occurred from the beginning... those reports are published in a public database on the Web by the FDA that anybody can access. This data's been out there in public the whole time."
According to Fogoros, the notification letter was issued to inform physicians of the data and does not encourage them to take any special action beyond the continued routine monitoring of their patients. "We are not advising them to replace these devices. Obviously, they need to consider what they see as their risk and their patients' individually, but based on the information that we have, we feel that this is pretty solid information; these devices are as safe as any [ICD] that's out there today," he said.
Shorting Problem is Second ICD Flaw Reported This Year
However, regardless of how rare the problem is, physicians are understandably concerned, and even more so since this is the second time this year that a rare but important design flaw was revealed in an ICD device. In February, Medtronic (Minneapolis, Minnesota) issued a voluntary notification to physicians about a potential battery shorting mechanism that may affect certain models of its Marquis VR/DR and Maximo VR/DR ICDs and InSync I/II/II Marquis and InSync III Protect cardiac resynchronization therapy defibrillators. The defect may cause the devices to lose power and become nonfunctional over a short period of time. As reported previously by Medscape CRM (see Related Links below), the company made the decision to notify physicians of the flaw after it identified 9 clinical cases impacted by the battery defect. Medtronic recommends that physicians consider replacing the devices if a patient is pacemaker-dependent or has frequent therapies for pacing or ventricular fibrillation. Close monitoring is recommended for those in lower-risk categories. Reportedly, some 13,000 of the Medtronic devices have been changed out since the notification was issued.
With back-to-back problems at these two companies, physicians are now taking a much more critical look at how rare device defects such as these are managed by industry. Eric Prystowsky, MD, Director of the Clinical Electrophysiology Laboratory at St. Vincent Hospital (Indianapolis, Indiana) and Editor-in-Chief of Medscape CRM, told Medscape CRM that he understands why Guidant acted as it did, but he wishes the company had handled the situation differently.
Prystowsky, who is also a member of Guidant's advisory board, noted that it is not just an issue with Guidant, but with all EP device companies, which sooner or later have to deal with seemingly random failure events. "I know that [these companies] are very, very conscious of patient safety, so none of this in my opinion was because of reputation or anything like that," he said.
"They all have mechanisms in place to deal with rare failure events such that they will look at statistics and say it's still within the acceptable random failure rate." Even when the problem is clearly no longer random and companies have identified a known defect, if it occurs at a very small rate, "companies will look at statistics and say it's still within the acceptable failure range." However, Prystowsky said pointedly, "I don't like their paternalistic attitude — [implying] they know more about what I should do with my patient than I do."
Prystowsky believes Guidant should have informed doctors when the company first recognized the defect existed so that physicians could discuss the issue with their patients. "It's not Guidant's decision or Medtronic's decision when I'm sitting in front of my patient; it's my decision," he said. "Of course, part of that equation is that the EP implanting community, or whoever's doing the implanting, has to act responsibly. If people act responsibly, there will not be enormous numbers of ICDs changed out. There will absolutely be some, but there should not be enormous numbers."
Although Prystowsky does not agree with Guidant's recommendation not to replace any of the affected units, he is being selective with his patients in choosing who will receive a replacement, and his office is contacting all affected patients to discuss the issue. "The issue now is ethical on our side. We need to get the word out as soon as we can to all of our [affected] patients, let them know the issue, try to advise them yes or no for replacement, and have the full discussion." Prystowsky says he's likely to change out patients who are at high risk who have had multiple ICD shocks or are prone to getting shocks; but he's unlikely to change the device in patients who have ICDs for primary prevention.
Also at issue is the way the story broke in the public and medical communities, which has not made the aftermath any easier for physicians to deal with. The doctors who treated the young patient who died apparently have submitted the case for publication in the journal Heart Rhythm, and this is the appropriate way to do this, according to Prystowsky, who said these problems should be exposed through scientific discourse so that physicians can read about it and make treatment decisions.
"Instead [with the recent publicity], you have sort of mass hysteria," he complained. "The phones were ringing off the hook in our office yesterday... there clearly have been patients who have been scared over this."
Push for a Community-Wide Taskforce
To avoid these problems in the future, some in the EP community are pushing for the establishment of a community-wide task force to lay down specific guidelines detailing steps that companies would be required to follow in these cases. "We need to have some mechanism that says whenever this occurs, no matter what company is involved, a standard series of steps are taken," Prystowsky told Medscape CRM. This would potentially include guidelines that dictate when a company should suspend marketing of a particular product until a flaw is fixed, if that defect puts patients at risk. According to Prystowsky, developing "very high level ethical and reasonable guidelines" would require a team effort from industry, physicians, and the FDA and he thinks that the Heart Rhythm Society is the body that should at least bring people to the table. "It's not something that's going to be done overnight — this is a very, very difficult area with lots of ramifications... but if everyone agrees on a standard that should be met, I think it has to be enforced."
By Staff Writer, Medscape CRM