TOPLINE:

In patients younger than 19 years with implantable cardioverter defibrillators (ICDs), appropriate shocks were more common with a lower weight (indicating younger age), although adverse events did not differ by weight. Many inappropriate shocks involved inadequate medication or poor adherence.

METHODOLOGY:

• This retrospective cohort study in Sweden aimed to quantify the incidence and prevalence of paediatric ICDs, to identify risk factors for appropriate shocks and adverse events, and to assess medication adequacy and compliance.
• Researchers included 120 patients younger than 19 years (71 boys) implanted with an ICD between 1995 and 2017 at a median age of 14.7 years, with a median follow-up duration of 7.1 years.
• Primary prevention ICDs were implanted in 45% of patients, with cardiomyopathy (46%) and primary electrical disease (41%) being the predominant underlying conditions.
• Endpoints included the time to the first appropriate or inappropriate shock, the time to the first ICD-related complication requiring reintervention, and composite adverse events; medication adequacy and compliance were assessed at the time of shocks.
• The analysis included the comparison between patients with a lower weight (< 30 kg) and higher weight (≥ 30 kg); a lower weight was used as a proxy for age indicating the younger group.

TAKEAWAY:

• The incidence of paediatric ICD implantation peaked at 0.56 per 100,000 person-years in 2010-2013 and was 0.45 per 100,000 person-years in 2018-2021.
• The estimated 5-year survival without appropriate shocks was 68%, without inappropriate shocks was 84%, without complications was 82%, and without adverse events was 71%.
• The risk for appropriate shocks was 3.7-fold higher with secondary prevention ICDs than with primary prevention ICDs (P = .001) and 2.7-fold higher in patients with a lower vs higher weight (P = .008). Adverse events did not differ by weight.
• Less than half of inappropriate shock episodes (46%) occurred with adequate medication and good compliance, and 42% of patients with appropriate shocks had at least one episode with inadequate or no medication or poor compliance.

IN PRACTICE:

"[The study] findings underline the importance of applying universally accepted criteria and guidelines for ICD implantation even in younger patients," the researchers wrote.

"This means that many shocks and life-threatening events could be avoided with a more active treatment regimen and optimized pharmacological treatment," they added.

SOURCE:

This study was led by Camilla Wirestrand, MD, Karolinska Institutet, Stockholm, Sweden. It was published online on December 11, 2025, in EP Europace.

LIMITATIONS:

Because the study was retrospective and had missing data, researchers could not control all factors or analyse device programming. Small subgroups and few very young children made differences hard to detect. The long time span and mostly transvenous systems made the results less generalisable.

DISCLOSURES:

This study received support through grants from the Samariten Foundation and Swedish ICD and Pacemaker Registry. The authors declared having no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.