DERIVATION OF A DEFIBRILLATOR IMPLANT CRITERION BASED ON PROBABILITY OF SUCCESSFUL DEFIBRILLATION

Common criteria for implant of a cardioverter defibrillator include ve rification of a 2:1 energy safety margin or a fixed safety margin of 1 0 joules. These criteria have been established empirically. We present a statistical model bused on defibrillation efficacy curves which may be used to establish a criterion which would meet a predetermined tar get. As an example, an implant criterion is derived based on a goal of 1-year sudden cardiac death survival of at least 99% by selecting an expected first-shock efficacy to meet that target. Logistic regression was performed on data from over 1,500 defibrillator implants includin g successful epicardial and transvenous electrode system implants as w ell as data from unsuccessful implants, A random sample from these cur ves was used to generate a representative sample of 1,000 potential im plant candidates, By assuming successful defibrillation using a series of shocks at specified energies, i.e., choosing an implant criterion, the probability of successful defibrillation of the patient by a sing le shock at a predetermined maximum output can be established. Indepen dent data are used to validate the model's accuracy in predicting defi brillation efficacy within the derived example.