Background Sudden cardiac death (SCD) in young individuals and athletes is generally caused by hereditary cardiac conditions, including cardiomyopathies such as hypertrophic cardiomyopathy (HCM). Although historically HCM has been reported as the predominant cause of SCD in young athletes, it is unclear as to what degree exercise is a trigger for possible fatal arrhythmias.

Aim We aimed to report on the circumstances of SCD in a cohort of young individuals aged ≥ 10 and < 30 whose autopsy was consistent with HCM.

Methods We reviewed 6860 consecutive cases of SCD referred to our specialist cardiac pathology centre 1994 and 2020. SCD was defined as death from a cardiovascular cause within 12 hours of apparent well-being. All cases underwent detailed autopsy evaluation of the heart, including histological analysis, by expert cardiac pathologists. A minimum of 10 blocks of tissue were taken for histological analysis. HCM was defined by the presence of increased heart weight or increased wall thickness and significant myocyte disarray at histological examination.

Results Of the total cases of SCD, 264 (4%) were due to HCM. Our cohort of young decedents comprised of 66 individuals (average age 21±5 years, males 76%). For the majority (n=52, 79%) SCD was the first manifestation of HCM. The average heart weight was 507±152 grams and left ventricular (LV) fibrosis was found in 28 (42%) cases (Figure 1A). Death was more common between 16 and 20 years of age (n=24) (Figure 1B). Death occurred during exertion in 25 (38%) individuals and at rest or during daily activities in the remaining 41 (62%), including 5 individuals who died during sleep. Male sex was more represented among decedents who died during exertion (88% compared with 68% in the group that died at rest, p=0.07); LV fibrosis was more commonly observed in individuals who died during exertion (56% compared with 34% in the group who died at rest, p=0.08). Younger individuals between 10–15 years of age died mostly during exercise (80%), in other age groups death occurred mainly at rest (33% in age group 16–20 years, 30% in age group 21–25 years, 33% in age group 26–30 years) (Figure 1B).

Conclusion We observed a high age-related variability in terms of circumstances of death. In the context of HCM, our findings suggest that individuals aged 10–15 years are the most vulnerable in terms of exercise-related-SCD. This exemplifies the importance of preventative cardiac screening in young individuals who might be harbouring quiescent cardiac conditions associated with young SCD.

Conflict of Interest None