High Incidence of Appropriate and Inappropriate ICD Therapies in Children and Adolescents with Implantable Cardioverter Defibrillator

Abstract

Appropriate and inappropriate therapies of implantable cardioverter defibrillators have a major impact on morbidity and quality of life in ICD recipients, but have not been systematically studied in children and young adults during long-term follow-up. ICD implantation was performed in 20 patients at the mean age of 16 +/- 6 years, 11 of which had prior surgical repair of a congenital heart defect, 9 patients had other cardiac diseases. Implant indications were aborted sudden cardiac death in six patients, recurrent ventricular tachycardia in 9 patient, and syncope in 5 patients. Epicardial implantation was performed in 6 and transvenous implantation in 14 patients. Incidence, reasons and predictors (age, gender, repaired congenital heart disease, history of supraventricular tachycardia, and epicardial electrode system) of appropriate and inappropriate ICD therapies were analyzed during a mean follow-up period of 51 +/- 31 months range 18-132 months. There were a total 239 ICD therapies in 17 patients (85%) with a therapy rate of 2.8 per patient-years of follow-up. 127 (53%) ICD therapies in 15 (75%) patients were catagorized as appropriate and 112 (47%) therapies in 10 (50%) patients as inappropriate, with a rate of 1.5 appropriate and 1.3 inappropriate ICD therapies per patient-years of follow-up. Time to first appropriate therapy was 16 +/- 18 months. Appropriate therapies were caused by ventricular fibrillation in 29 and ventricular tachycardia in 98 episodes. Termination was successful by antitachycardia pacing in 4 (3%) and by shock therapy in 123 episodes (97%). Time to first inappropriate therapy was 16 +/- 17 months. Inappropriate therapies were caused by supraventricular tachycardia in 77 (69%), T wave oversensing in 19 (17%), and electrode defect in 16 episodes (14%). It caused shocks in 87 (78%) and only antitachycardia pacing in 25 episodes (22%). No clinical variable could be identified as predictor of either appropriate or inappropriate ICD therapies. There is a high rate of ICD therapies in young ICD recipients, the majority of which occur during early follow-up. The rate of inappropriate therapies is as high as 47% and is caused by supraventricular tachycardia and electrode complications in the majority of cases. Prospective trials are required to establish preventative strategies of ICD therapies in this young patient population.

Incidência de choques e qualidade de vida em jovens com cardioversor-desfibrilador implantável

“…Clinical and epidemiological aspects of the population of our study, number of patients involved, mean age, etiology of the cardiovascular disease, and indication for ICD implantation are similar to those of the three most recent studies 8,10,11 . Mortality in these studies ranged from 4.2% to 20% during the mean follow-up period of 3.6 years, and was also similar to our results, which showed a mortality rate of 13.8%.…”

“…In the young population, indications for this device are different from those for the adult population because they are mostly restricted to the primary or secondary prevention of sudden death in genetic diseases: congenital long-QT syndrome, Brugada syndrome, hypertrophic cardiomyopathy, and arrithmogenic dysplasia of the right ventricle [6][7][8][9][10][11] .…”

Primary prevention with the ICD in clinical practice: not as straightforward as the guidelines suggest?

“…23,24 Younger patients may be more susceptible for inappropriate shocks. 25,26 Elderly patients and primary ICD implant: an unspoken territory Guidelines for primary prevention do not refer to any age limits, possibly reflecting that the influence of age on outcome during the study period in both pivotal trials is ambiguous. When the SCD-HeFT population is dichotomised for age, only patients <65 years showed advantage from an ICD.…”

Inappropriate ICD Shocks in Pediatric and Congenital Heart Disease Patients

“…16,25,27 However, most studies of ICD use in pediatric and CHD patients have found rates of IS to be between 20% and 30% in these patient populations, 10,11,13,14,[34][35][36][37][38][39][40] with some studies observing IS in up to 40% to 50% of patients and, in some instances, with inappropriate shocks being more frequent than appropriate shocks. 12,19,41,42 This is likely a result of a more active lifestyle, faster rates of sinus tachycardia, longer duration of implantation, smaller patient size, and a higher rate of device and lead complications relative to adult patients. 11,15 Inappropriate shocks are painful events that confer no benefit to patients, are associated with worsened psychosocial and clinical outcomes, and are particularly frequent in the pediatric and CHD ICD populations.…”

“…Most studies have found that at least 40%, and up to 100%, of patients are on antiarrhythmic medications, primarily b-blockers. 10,13,[39][40][41][47][48][49] This may be a reflection of the different substrates present in the pediatric and CHD population, particularly channelopathy patients, in whom b-blockers are a mainstay of treatment. The use of antiarrhythmic medication has not been conclusively demonstrated to reduce the level of shock burden in this population, despite the common practice of altering medical management in patients who receive shocks.…”