Evaluation of ICD function can now be performed noninvasively with intravenous sedation. To determine the value of follow-up electrophysiological studies for ICD implants, we performed a retrospective review of predischarge and 2-month ICD re studies, identifying critical problems uncovered. Of the 123 patients implanted, 122 had a predischarge study, 105 had both predischarge and elective 2-month follow-up studies, and 1 patient expired prior to restudy. Patients who underwent 2-month studies for nonelective indications (e.g., frequent shocks) were excluded from analysis. Programming changes were made in 62% of the predischarge studies (n = 122) and 70% of the elective 2-month studies (n = 105). The average number of programming changes per study was 1.3 for predischarge testing and 1.1 for 2-month testing. The most common changes at predischarge testing were adjustment of the tachyarrhythmia rate cutoff (35%) and at 2-month study, reprogramming of bradycardia pacing parameters (41%). Of the patients who underwent both predischarge and 2-month testing, 91% had programming changes in at least one of their re studies. Of 227 re studies performed, 18 studies in 14 patients yielded 24 critical findings which included: DFT increases to > or = 25 J (n = 13); sensing abnormalities of induced ventricular arrhythmia (n = 6); dislodged lead (n = 2); and serious pacemaker interactions (n = 3). Six of these critical cases (5% of total patients) required reoperation. The data suggests that routine ICD restudy is a valuable tool for management of the ICD patient. Additionally, ICD restudy is likely to increase the diagnostic yield of clinically silent critical system problems that could result in device failure.