High prevalence of cardiac symptoms preceding paediatric out-of-hospital cardiac arrest

Background Out-of-hospital cardiac arrest (OHCA) in children is a rare but devastating event, with an estimated incidence of 8-9 per 100,000 person years and a survival rate of less than 10%. OHCA may be the presenting event in children with undiagnosed cardiovascular disease, who were previously believed to be fit and well. A substantial proportion of adults experiencing an unexpected OHCA report previous warning symptoms, but whether the same is true in paediatric OHCA survivors has not been systematically evaluated previously. Purpose The aim of this study was to describe the prevalence of cardiac symptoms in children prior to their presentation with OHCA. Methods Clinical records of 58 consecutive children (birth to 18 years old) presenting with a resuscitated OHCA without a known pre-existing cardiac diagnosis between 1996 and 2025 to a single paediatric tertiary referral centre for inherited cardiovascular disease were retrospectively reviewed. Results The median age at cardiac arrest was 11 (IQR 7 – 14) years. Twenty-nine OHCA (50%) occurred on exertion. Following the OHCA, 42 patients (72.4%) were diagnosed with an inherited cardiac condition (figure 1); hypertrophic cardiomyopathy (n=17, 29.3%), and catecholaminergic polymorphic ventricular tachycardia (n=10, 17.2%) were the most common diagnoses. In 13 patients (24.1%), no cause was identified despite thorough phenotypic investigation. Eleven patients (18.9%) had a significant neurological deficit as a consequence of the cardiac arrest. 18 patients (31.0%) had a distant family history of sudden cardiac death (SCD). 28 patients (48.3%) had reported cardiac symptoms prior to their OHCA (figure 2), 13 (22.4%) of whom had experienced syncope; 9 out of the 13 (81.8%) patients’ syncopal events occurred on exertion, with 8 of those 9 patients subsequently having an OHCA in the same circumstances. Of those who experienced cardiac symptoms, 25.9% (n=7) reported more than one symptom. Of the 13 patients who experienced syncope, 3 sought medical attention and had a resting 12-lead ECG performed with no abnormality detected; none had further follow-up arranged. Patients with prior cardiac symptoms were older than those without (p=.001), but there were otherwise no significant differences between the groups. Conclusion Almost half of paediatric OHCA survivors had warning symptoms prior to their event, with over 20% having previously experienced a syncopal event, representing potential missed opportunities to identify an underlying diagnosis prior to a cardiac arrest. These findings highlight the need for more education, both for medical professionals and the general public, about ‘red flag’ symptoms. In addition, a third of patients had a family history of SCD, representing another potential missed opportunity for family screening.