Reliability, Failure Rates for Cardiac Devices
Pacemakers and implantable cardioverter-defibrillators (ICDs) are among the most clinically important and technically complex medical devices in use today, but several recent high-profile device malfunctions have called into question their safety and reliability.
Two reports in the April 26, 2006 issue of The Journal of the American Medical Association (JAMA) offer new insights into pacemaker and implantable cardioverter-defibrillators performance by providing the most comprehensive analysis of malfunction data available to date.
"Despite millions of pacemaker and ICD implants worldwide and their increasingly frequent use, surprisingly little is known about device reliability," says the studies' lead author William H. Maisel, MD, MPH, director of the Pacemaker and Device Service at Beth Israel Deaconess Medical Center (BIDMC) and Assistant Professor of Medicine at Harvard Medical School. The devices work to stabilize abnormal heart rhythms, pacemakers by treating hearts that beat too slowly and implantable cardioverter-defibrillatorss by treating heart rhythms that have become dangerously fast.
In the first study, which Maisel performed with colleagues at the U.S. Food and Drug Administration (FDA), he found that, between the years of 1990 and 2002, there were 2.25 million pacemakers and almost 416,000 ICDS implanted in the U.S. During this same time period, 17,323 devices (8,834 pacemakers and 8,489 ICDs) were surgically removed from patients due to a confirmed device malfunction. (Battery, capacitor and electrical abnormalities accounted for approximately half of the device failures.) In addition, 61 patient deaths were attributed to pacemaker or implantable cardioverter-defibrillator malfunction during this 13-year period.
"Overall, the annual ICD malfunction replacement rate of 20.7 per 1,000 implants was significantly higher than the pacemaker malfunction replacement rate of 4.6 per 1,000 implants," notes Maisel. "While pacemakers became increasingly reliable during the study period, a marked increase in the ICD malfunction replacement rate was observed between 1998 and 2002, suggesting that