Pacemaker and ICD Malfunction—An Incomplete Picture

Abstract

IN THIS ISSUE OF JAMA, THE REPORTS BY MAISEL AND COLleagues and by Gould and Krahn represent substantial pieces of an information mosaic that is developing about life-sustaining and life-saving implantable arrhythmia device technologies. It is apparent, not only to the medical community, but also to patients, the press, regulators, investors, and the legal community, that this information mosaic is complex. The technologies are complex. The medical issues are complex. The ethical issues are complex. The financial issues are complex. No effort should trivialize this complexity or oversimplify and produce “the solution” without understanding that the information comes with gaps and never forms more than an incomplete mosaic. These 3 studies provide new data to inform the most important issue—how physicians and patients should make individual decisions regarding pacemaker or implantable cardioverter-defibrillator (ICD) surgery. In the first study, Maisel uses meta-analysis to evaluate the incidence of pacemaker and ICD malfunction requiring device explantation. There are strengths and weaknesses in this approach. A significant strength is the longitudinal perspective, providing outcomes for pacemakers from 1983 through 2004 and for ICDs from 1988 through 2004. Unfortunately, only 3 registries contributed data to the meta-analysis. The Bilitch North American Registry was voluntary and not a complete registration of all devices, representing 6 pacemaker sites and 13 ICD sites that ended malfunction reporting in 1993. The UK National Pacemaker and ICD Registry included all pacemaker and ICD implantations in the United Kingdom and Republic of Ireland but contributed data on pacemaker malfunction only from 1983 through 2004. The Danish Pacemaker and ICD Registry reported information about all devices implanted in every Danish center (14 pacemaker and 5 ICD) and contributed malfunction data between 1994 and 2004. The consistency of the reported pacemaker malfunction incidence between the Bilitch and UK registries from 1983 through 1993 and between the UK and Danish registries between 1994 and 2004 is reassuring. However, a noteworthy regional difference was noted in 2001, with a substantially higher pacemaker malfunction rate in the Danish Registry related to an unfortunate choice of a pacemaker model. Although there was a clear decline in the pacemaker malfunction rate with a leveling of the incidence from 1988 through 2004, the trends for the ICD patients (dependent on the Bilitch Registry from 1988-1993 and the Danish Registry from 1994-2004) are much less clear and appear to vary significantly. In a second study, Maisel et al estimate the rate of device malfunction using the number of manufacturerconfirmed malfunctions that caused device explantation as reported to the US Food and Drug Administration (FDA) through annual reports, as compared with the number of device implantations each year, between 1990 and 2002. This is a substantially different methodology with an end point similar to that of the meta-analysis approach that was indexed to device prevalence. Although no attempt was made to measure the number of devices at risk for malfunction, “all” device explantations due to device malfunction were counted. The strength of this approach is the enormous number of devices (2.25 million pacemakers and 415 780 ICDs) that were implanted in the United States and therefore at risk for premature explantation and analysis. Despite the magnitude of this data set, there are 3 substantial gaps in the data. Manufacturers and hospitals are required to report by FDA regulation all pacemaker and ICD malfunctions, especially those that result in a surgery. However, some device malfunctions may be missed due to poor communication, failed administrative issues in the operating room, or inconsistent physician reporting. A second, more important, gap is that patients who die either with or possibly in part related to a malfunctioning device may be missed. Third, and perhaps most important, pacemakers and ICDs are dependent on the entire implanted system to function properly. The device, the leads, the chosen programmed parameters, and the patient’s response are all interdependent. The system malfunction rate may be the most impor-