PREDISCHARGE ARRHYTHMIA INDUCTION TESTING OF IMPLANTABLE DEFIBRILLATORS MAY BE UNNECESSARY IN SELECTED CASES

Complete postoperative evaluation of implantable cardioverter-defibril lators (ICDs) before discharge, including arrhythmia induction, has be en the standard since their introduction, Whereas the original ICDs pr ovided little telemetered information and used separate pace-sense and defibrillation leads, modern, third-generation devices provide pace-s ense function information in addition to other data and are used in co njunction with integrated transvenous endocardial leads that combine p ace-sense and defibrillation function. Changes in lead position, which can potentially result in either an inability to detect fibrillation or to terminate it, should be mirrored by changes in resting pace-sens e function. Thus, for newer ICDs implanted with integrated endocardial lead systems, it is possible that in at least some cases predischarge arrhythmia inductions can be avoided. Two hundred patients receiving third-generation ICDs in conjunction with integrated transvenous leads were evaluated before discharge. Defibrillation detection or terminat ion problems were seen in 8. Declines in resting R-wave amplitude and pacing impedance were significantly associated with such complications (-7 +/- 5 vs -0.3 +/- 2.3 mV [p <0.0001] and -158 +/- 138 vs -93 +/- 76 Omega [p <0.05], for those with vs without complications, respectiv ely), as were gross right ventricular lead migrations on chest x-ray. No patient with a defibrillation complication had an R-wave change of <3 mV. However, 13% of patients without complications had R-wave chang es of >3 mV. It is concluded that a pace-sense evaluation of ICDs may be a satisfactory screen to determine those who need to go on to compl ete testing with arrhythmia induction in selected cases. (C) 1997 by E xcerpta Medico, Inc.