Pacemaker and ICD generator malfunctions: analysis of Food and Drug Administration annual reports.
BACKGROUND
Pacemakers and implantable cardioverter-defibrillators (ICDs) are complex medical devices proven to reduce mortality in specific high-risk patient populations. It is not known if increasing device complexity is associated with decreased reliability.


OBJECTIVE
To analyze postapproval annual reports submitted to the US Food and Drug Administration (FDA) by manufacturers of pacemakers and ICDs to determine the reported number and rate of pacemaker and ICD malfunctions and to assess trends in device performance.


METHODS
Pacemaker and ICD annual reports submitted to the FDA for the years 1990-2002 were reviewed. A pacemaker or ICD generator was defined as having malfunctioned if it was explanted due to an observed malfunction, returned to the manufacturer, and confirmed by the manufacturer to be functioning inappropriately. Leads and biventricular devices were not included in the study. Deaths were attributed to device malfunction only if they were witnessed, the malfunction immediately led to the death, and the malfunction was confirmed by the manufacturer.


METHODS
Number of implanted pacemaker and ICD generators; number of reported malfunctions; and annual malfunction replacement rates. Generator malfunction replacement rates were defined as the annual number of replacements due to confirmed malfunction divided by the annual number of implants.


RESULTS
During the study period, 2.25 million pacemakers and 415,780 ICDs were implanted in the United States. Overall, 17,323 devices (8834 pacemakers and 8489 ICDs) were explanted due to confirmed malfunction. Battery/capacitor abnormalities (4085 malfunctions [23.6%]) and electrical issues (4708 malfunctions [27.1%]) accounted for half of the total device failures. The annual pacemaker malfunction replacement rate per 1000 implants decreased significantly during the study, from a peak of 9.0 in 1993 to a low of 1.4 in 2002 (P = .006 for trend). In contrast, the ICD malfunction replacement rate per 1000 implants, after decreasing from 38.6 in 1993 to 7.9 in 1996, increased markedly during the latter half of the study, peaking in 2001 at 36.4 (P = .04 for trend). More than half of the reported ICD malfunctions occurred in the last 3 years of the study. Overall, the annual ICD malfunction replacement rate was significantly higher than the pacemaker malfunction replacement rate (mean [SD], 20.7 [11.6] vs 4.6 [2.2] replacements per 1000 implants; P<.001; rate ratio, 5.9 [95% confidence interval, 2.7-9.1]). Sixty-one deaths (30 pacemaker patients, 31 ICD patients) were attributable to device malfunction.


CONCLUSIONS
This study demonstrates that thousands of patients have been affected by pacemaker and ICD malfunctions, the pacemaker malfunction replacement rate has decreased, the ICD malfunction replacement rate increased during the latter half of the study, and the ICD malfunction replacement rate is significantly higher than that for pacemakers. Although pacemakers and ICDs are important life-sustaining devices that have saved many lives, careful monitoring of device performance is still required.
Maisel
William H
WH
Cardiovascular Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Mass 02215, USA. wmaisel@bidmc.harvard.edu
Moynahan
Megan
M
Zuckerman
Bram D
BD
Gross
Thomas P
TP
Tovar
Oscar H
OH
Tillman
Donna-Bea
DB
Schultz
Daniel B
DB
D017147:Defibrillators, Implantable / Q000009:adverse effects; D004868:Equipment Failure; D006801:Humans; D010138:Pacemaker, Artificial / Q000009:adverse effects; D011358:Product Surveillance, Postmarketing; D014481:United States; D014486:United States Food and Drug Administration