title: Pacemaker and ICD generator reliability: meta-analysis of device registries.
abstract: BACKGROUND
  Despite there being millions of pacemaker and implantable cardioverter-defibrillator (ICD) generator implants worldwide, little is known about device reliability.
  
  
  OBJECTIVE
  To perform a meta-analysis of prospective pacemaker and ICD registries to determine annual rates of pacemaker and ICD malfunction and to identify trends in these rates.
  
  
  METHODS
  MEDLINE (January 1966 to April 2005), the Cochrane Central Register of Controlled Trials (through second quarter 2005), the Cochrane Database of Systematic Reviews (through second quarter 2005), and a bibliographic review of secondary sources. Search terms included pacemaker, artificial; defibrillators, implantable; registries; performance; and malfunction.
  
  
  METHODS
  Eligible registries were prospective; reported the number of patients with pacemaker, ICD, or both; and allowed determination of the annual number of device malfunctions. Of 1007 references screened, 3 registries meeting the selection criteria were identified and included 2.1 million pacemaker person-years and 14,821 ICD person-years of observation.
  
  
  METHODS
  Included the annual number of patients with pacemakers and ICDs at risk of device failure and the annual number of generator malfunctions (1983-2004 for pacemakers, 1988-2004 for ICDs). A device malfunction was defined as an integral component failure that required device explantation prior to reaching elective replacement. Failures of pacemaker and ICD electrodes were not included in the study.
  
  
  RESULTS
  There were 2981 pacemaker and 384 ICD generator malfunctions. Pacemaker reliability improved markedly during the 1980s (P for trend <.001) and the pacemaker malfunction rate remained low during the remainder of the study. Implantable cardioverter-defibrillator reliability improved during the first 10 study years (P for trend <.001). From 1998-2002, however, the ICD malfunction rate increased more than 4-fold (P for trend <.001), before decreasing substantially in the latter 2 years of the study. Overall, the mean (SE) annual ICD malfunction rate was about 20-fold higher than the pacemaker malfunction rate (26.5 [3.8] vs 1.3 [0.1] malfunctions per 1000 person-years, P<.001). Battery malfunctions were the most common cause of device failure.
  
  
  CONCLUSIONS
  Pacemaker reliability has improved markedly. In contrast, after more than a decade of improving device reliability, the ICD malfunction rate transiently increased before experiencing substantial reductions in the latter 2 study years. Whether increasing device sophistication accounts for the observed decrease in reliability is not known. Continued monitoring of pacemaker and ICD performance is required.
authors.affiliation: Cardiovascular Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Mass 02215, USA. wmaisel@bidmc.harvard.edu
authors.forename: William H
authors.initials: WH
authors.lastname: Maisel
mesh_terms: D017147:Defibrillators, Implantable / Q000009:adverse effects*; D004868:Equipment Failure / Q000706:statistics & numerical data*; D006801:Humans; D010138:Pacemaker, Artificial / Q000009:adverse effects*; D012042:Registries