根據一份在八月十五日JAMA期刊的新分析指出，心臟機械輔助裝置，如心臟節律器或植入性心室去纖維震顫器可能無法相當有節律、規律地運作；而同時也指出，FDA對於上述兩類裝置的勸告、警告及回收都有逐漸增加的趨勢。主筆者William H. Maisel, MD, MPH,現為哈佛大學的指導員，其同事研究了自一九九零年一月至兩千年十一月以來十一年FDA的檔案紀錄。他表示FDA在這陣子發出了五十二項的警訊，過去的平均數是一年四次，而那些對上述兩項裝置的勸告在近五年來也一直升高。
Pacemakers and ICDs Subject to Frequent Recalls
FDA Issued Safety Alerts for More Than Half a Million Devices
By Peggy Peck
WebMD Medical News
Reviewed by Aman Shah, MD
Aug. 14, 2001 -- Mechanical heart aids such as pacemakers or implantable cardioverter-defribrillators (ICDs) may not "take a lickin' and keep on tickin'," according to a new analysis in the Aug. 15 issue of JAMA, which shows that the number of FDA advisory, alerts, and recalls of pacemakers and ICDs is increasing.
Lead author William H. Maisel, MD, MPH, an instructor at Harvard Medical School, and colleagues studied FDA records over an 11-year period from January 1990 through December 2000. He says that the FDA issued 52 alerts during that period, "an average of about four a year," and that the number of advisories appears to be increasing for both devices over the last 5 years.
The alerts, which ranged from actual recalls to advisories about very minimal problems with the programming of some devices, "have the potential of being very expensive to fix," Maisel tells WebMD. The alerts affect more than 400,000 pacemakers and nearly 115,000 ICDs. "We estimate the cost of these advisories to be about $870 million," he says.
The majority of the advisories -- 35 out of 52 -- involved hardware problems and affected more than 280,000 devices, and most of the rest -- 10 of the 52 -- related to computer problems.
Although more pacemakers were the subjects of FDA action, Maisel says that the recall rate is actually higher for ICDs than for pacemakers (16.7 vs. 6.7 advisories/100 person-years). But because ICD technology is newer, there are fewer devices in use and therefore a lower number of advisories. This is worrisome, says Maisel, because an ICD failure has a greater potential for harm.
"We don't know why the advisory rate is increasing. ... There are several theories ... possibly that the technology race to produce smaller units may have [an effect] ... possibly we are just doing a better job of detecting malfunctions, being more careful in monitoring the devices. I don't think this analogous to postmarket surveillance of drugs. I don't think it is a simple matter of more events because there is more exposure," says Maisel.
"There are very few reported, confirmed deaths due to device failure. But these patients are sick, and when they die, death is likely to be attributed to a cardiac abnormality. But we just don't know if some device malfunction was a contributing factor," he says.
Eric N. Prystowsky, MD, president of the North American Society of Pacing and Electrophysiology (NASPE) and a consultant to Guidant, a manufacturer of both ICDs and pacemakers, says his group welcomes Maisel's study because "it is the first attempt ... to track all these reports."
But he says the study has to be assessed realistically. Prystowsky oversees the implantation of 400 pacemakers and 200 ICDs each year and says that he is well aware of the frequency of safety alerts. Yet, he says, "even with all these alerts, it is exceedingly uncommon to bring back patients to replace a device," and most alerts require little more than more frequent office visits to better monitor the patient.
Prystowsky says that it is, therefore, unlikely that device alerts cost anywhere near $870 million because "that figure is based on the assumption that all devices are replaced." Maisel, on the other hand, feels that the figure is conservative.
Although Maisel's paper tracks the number of FDA-issued alerts, it doesn't provide any data on the health effects of those alerts. He explains that the FDA warnings are the only official records available. When an alert is issued, a notice goes out to the physician who implanted the device and the patient in whom it was implanted. It is then up to the physician and the patient to decide how to respond, says Maisel.
"I think it falls to NASPE to develop some guidelines to determine at what point an alert or a recall should be issued and to provide some guidance on follow-up. ... We would welcome participation by our colleagues from the AHA and ACC, but this is really an issue for us," says Prystowsky. "We are the physicians who specialize in this field." He says that his group is already planning a conference aimed at addressing device safety concerns.
Accompanying editorial author Kim A. Eagle, MD, chief of clinical cardiology at the University of Michigan Medical Center in Ann Arbor, tells WebMD that tracking devices after they are implanted is actually "a lot more complicated than tracking side effects of pills. It is much more challenging because the devices are more complex."
However it is done, Eagle says it's clear that better device safety monitoring is needed. "What is very clear is that the recall carries with it a certain amount of inconvenience and expense," she says. "It has a direct impact on patient safety, although the lion's share of the recalls are not life-and-death issues."