Impact of genetic tests on survivors of paediatric sudden cardiac arrest

OBJECTIVE: To retrospectively investigate the clinical spectrum, genetic profiles and outcomes of survivors of paediatric sudden cardiac arrest (SCA). DESIGN AND PATIENTS: All 66 patients (aged 1-20 years), with unexpected SCA or syncope related to ventricular tachycardia (VT)/fibrillation and who survived to discharge from a tertiary centre, were enrolled from 1995 to 2018. Of these, 30 with underlying diseases prior to the events were excluded. Whole-exome sequencing targeting 384 channelopathy and cardiomyopathy-related genes (composite panel) was conducted to identify the possible genetic variants/mutations. RESULTS: A total of 36 patients were enrolled. Male adolescents predominated (66.7%), and the median age at onset was 13.3 years. Events occurred most often during exercise and daily activities. The yield rate of the genetic test was 84.6% (22/26); 14 had pathogenic variants; and 8 had likely pathogenic variants. The most common diagnoses were long QT in nine (25%), catecholaminergic polymorphic VT in six patients (16.7%), but other long QT and cardiomyopathy genes were also detected in eight patients (30.7%). The 10-year transplantation-free survival rate was 87.8% and was better for those who received genetic tests initially at the disease onset. An implantable cardioverter-defibrillator was implanted in 55.6% of the patients, with an appropriate shock rate of 61.1%. The defibrillator shock rate was lower for those who received composite panel initially. CONCLUSION: Survivors of SCA in the paediatric population had favourable long-term outcomes aided by genetic test. A broad composite genetic panel brings extra diagnostic value in the investigation of ventricular fibrillation/sudden cardiac death.