Clinical predictors of successful implantable cardioverter defibrillator implantation.

Successful implantation of an implantable cardioverter defibrillation system is critically dependent on demonstration that the lead system to be implanted can defibrillate reliably. Defibrillation efficacy in turn is dependent on several sets of factors that include: (1) defibrillation technique and the lead system being tested; (2) defibrillation testing protocol and criteria for implantation; and (3) clinical variables that may be intrinsic to the patient or extrinsic factors to which the patient is being exposed. Existing clinical data are limited but suggest that poor left ventricular function is the clinical variable most consistently associated with poor defibrillation efficacy and a failure to meet implant criteria of the epicardial lead systems. Antiarrhythmic drugs may elevate the defibrillation threshold, but evidence that this has important clinical ramifications on implantation success rates is very limited and incomplete.