Time dependence of risks and benefits in pediatric primary prevention implantable cardioverter-defibrillator therapy.

BACKGROUND: Implantable cardioverter defibrillators (ICDs) used to prevent sudden cardiac arrest in children not only provide appropriate therapy in 25% of patients but also result in a significant incidence of inappropriate shocks and other device complications. ICDs placed for secondary prevention have higher rates of appropriate therapy than those placed for primary prevention. Pediatric patients with primary prevention ICDs were studied to determine time-dependent incidence of appropriate use and adverse events.

METHODS AND RESULTS: A total of 140 patients aged <21 years (median age, 15 years) at first ICD implantation at Boston Children's Hospital (2000-2009) in whom devices were placed for primary prevention were retrospectively identified. Demographics and times to first appropriate shock; adverse events (including inappropriate shock, lead failure, reintervention, and complication); generator replacement and follow-up were noted. During mean follow-up of 4 years, appropriate shock occurred in 19% patients and first adverse event (excluding death/transplant) occurred in 36%. Risk of death or transplant was ≈1% per year and was not related to receiving appropriate therapy. Conditional survival analysis showed rates of appropriate therapy and adverse events decrease soon after implantation, but adverse events are more frequent than appropriate therapy throughout follow-up.

CONCLUSIONS: Primary prevention ICDs were associated with appropriate therapy in 19% and adverse event in 36% in this cohort. The incidence of both first appropriate therapy and device-related adverse events decreased during longer periods of follow-up after implantation. This suggests that indications for continued device therapy in pediatric primary prevention ICD patients might be reconsidered after a period of nonuse.