Out-of-hospital cardiac arrest in Norwegians aged 12-49 years: nationwide analysis of preceding symptoms and risk factors related to aetiology and pre-arrest exercise habits.

Background: Out-of-hospital cardiac arrest (OHCA) in the young is a tragic event. Regular exercise reduces cardiovascular disease (CVD) risk but, at certain intensities and volumes, is associated with increased OHCA risk. Understanding symptoms, risk factors and aetiology is central for primary prevention. Objective: Assess symptoms and risk factors related to OHCA aetiology in young Norwegians, and the role of exercise volume. Method: We obtained data from the Norwegian Cardiac Arrest Registry (2015-2017), medical records, autopsy reports and questionnaires. Inclusion criteria were ages 12-49 years and OHCA of presumed cardiac aetiology. Results: Data from 134 individuals (81 survivors, 53 deceased) showed that CVD symptoms were present during both rest/everyday activity and exercise in most victims, and were reported by more survivors than by next-of-kin of the deceased (78% vs 60%). Only 12% had symptoms just during exercise. Ischaemic heart disease was the leading cause (58% in males vs 38% in females), followed by structural, non-ischaemic heart disease. Sudden unexpected death syndrome (SUDS) was most common in individuals aged ≤35 years. Risk factors were present in 74%, with family history for CVD most prevalent (51%) and overweight in at least 33%. There were no significant differences in symptoms, risk factors or OHCA aetiology related to exercise volume prior to OHCA. Conclusion: Symptoms and CVD risk factors were prevalent in young Norwegians suffering OHCA regardless of exercise volume. Ischaemic heart disease was the leading cause of OHCA. We suggest evaluating symptoms carefully and addressing risk factors to prevent OHCA in young Norwegians regardless of exercise habits.