title: To replace or not to replace: a systematic approach to respond to device advisories.
abstract: OBJECTIVE
  The decision of whether and when to replace a device in response to an "advisory" letter requires careful consideration, because device replacement carries related risks and is influenced by the clinical characteristics of the patient.
  
  
  RESULTS
  The risk/benefit of device replacement depends on four parameters: expected annual sudden cardiac death rate; residual device life; difference in failure rate between the device listed on the advisory letter and the replacement device; and the replacement procedure mortality risk. Using these four factors, we have developed an equation that provides the "number needed to replace" (NNR) to save one life. Per our model, patients implanted with a device with a failure rate approaching 1% and a probability of requiring device intervention >or=25% per year-in particular, pacemaker-dependent patients-have an NNR <250. Pacemaker-dependent patients, with devices having three or more years longevity, but with device failure rates >or=0.5%, have an NNR <100. Patients with arrhythmic risk <or=2.5% per year and those with devices having failure rates <0.1% have a high NNR and stand more risk to be harmed than benefited from device replacement.
  
  
  CONCLUSIONS
  Pacemaker-dependent patients and those with high arrhythmic risk (>or=25% annually) when having "advisory" devices with high failure rate (>or=1%) have an NNR <250 and, hence, could be considered for device replacement. Conversely, patients with arrhythmic risk <or=2.5% per year and those with devices having failure rates <or=0.1% have a high NNR or even risk of "harm" from device replacement. In all the intermediate cases, the NNR will quantify the benefit/risk ratio of replacement, thus helping physicians and patients decide on the preferred approach. The NNR methodology proposed here is also applicable to advisory notices issued to leads, but the high morbidity associated with lead replacement will generally rule out interventions to replace leads.
authors.affiliation: Molecular Cardiology, IRCCS Fondazione Maugeri, Pavia, Italy. spriori@fsm.it
authors.forename: Silvia G
authors.initials: SG
authors.lastname: Priori
authors.forename: Angelo
authors.initials: A
authors.lastname: Auricchio
authors.forename: Seah
authors.initials: S
authors.lastname: Nisam
authors.forename: Patrick
authors.initials: P
authors.lastname: Yong
mesh_terms: D000465:Algorithms; D001145:Arrhythmias, Cardiac / Q000209:etiology; D016757:Death, Sudden, Cardiac / Q000453:epidemiology; D003657:Decision Making; D017147:Defibrillators, Implantable / Q000009:adverse effects; D020878:Device Removal / Q000009:adverse effects / Q000401:mortality; D004868:Equipment Failure; D006801:Humans; D015233:Models, Statistical; D012086:Reoperation / Q000009:adverse effects / Q000401:mortality; D018570:Risk Assessment; D017180:Tachycardia, Ventricular / Q000401:mortality / Q000517:prevention & control / Q000628:therapy; D014693:Ventricular Fibrillation / Q000401:mortality / Q000517:prevention & control / Q000628:therapy