Heart devices have different malfunction rates

NEW YORK, Apr 27 (Reuters) Presumably due to their greater complexity, implantable cardioverter-defibrillators (ICDs) are much more likely than pacemakers to malfunction, new research shows. Still, the absolute risk of malfunction with either type of device is very low and for appropriately selected patients the benefits far outweigh the risks.

As the name implies, pacemakers help the heart maintain a steady, regular pace. By contrast, ICDs, which are much newer, avert potentially fatal heart rhythms by detecting and correcting early disturbances with a shock. The type of heart rhythm disturbance determines which type of device should be used.

The report, which appears in the Journal of the American Medical Association, also indicates that in the last decade, malfunction rates have dropped for pacemakers, but have increased for ICDs. The authors speculate that this may be because pacemakers are an older, developed technology, whereas ICDs are still evolving. The good news is that in recent years, malfunction rates for ICDs seem to have declined.

In a related study, appearing in the same journal, researchers show that ICD replacement in response to device advisories is often linked to serious complications, including death.

Dr William H Maisel, from Beth Israel Deaconess Medical Center in Boston, and colleagues reviewed pacemaker and ICD reports submitted to the US Food and Drug Administration between 1990 and 2002 to assess replacement rates due to malfunction. In a similar analysis, Maisel reviewed data from international device registries.

Of the 2.25 million pacemakers implanted in the United States during the study period, 8,834 were removed due to malfunction. For ICDs, 415,780 were implanted and 8,489 were removed. Half of all device failures were related to battery/capacitor abnormalities and electrical problems.

The overall annual malfunction replacement rate per 1,000 implants was 20.7 for ICDs compared with just 4.6 for pacemakers. Thirty deaths in pacemaker patients and 31 in ICD patients were attributed to device malfunction.

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