Exercise related sudden cardiac death (SCD) in the young - Pre-mortal characterization of a Swedish nationwide cohort, showing a decline in SCD among athletes.

Aims: To study the frequency, etiology, and premortal abnormalities in exercise-related sudden cardiac death (SCD) in the young in Sweden.

Methods: All subjects with SCD in 10-35-year olds in Sweden during 2000-10, were included (n = 514). Information about each case was retrieved from death certifications, autopsy- and medical records. The number of SCD in athletes was compared to national figures from 1992-99.

Results: Exercise-related SCD occurred in 12% (62/514) of the SCD-population, a majority being men (56/62; 90%). Cardiopulmonary resuscitation (CPR) was started in 87% (54/62). In total, 48% (30/62), had a cardiac diagnosis, symptoms, family history and/or ECG-changes, before the fatal event. The most prevalent autopsy diagnosis was sudden arrhythmic death syndrome (15/62; 24%). The frequency of hypertrophic cardiomyopathy (HCM) and arrhythmogenic right ventricular cardiomyopathy (ARVC) was significantly higher in exercise-related SCD compared to non-exertional SCD. Exercise-related SCD was more common in athletes (21/29) than in non-athletes (41/485) (P < 0.0001). The total number of SCDs/year in athletes 15-35 years old, are approximately halved in 2000-10 compared to the years 1992-99.

Conclusion: The increased risk of exercise-related SCD in HCM and ARVC underlines the importance of early detection and eligibility recommendations. There is a major reduction in deaths among athletes in the 2000s, compared to the previous decade. These results may partly be explained by improved acute preparedness for sudden cardiac arrest (CPR, defibrillation), but as a substantial percentage have preceding risk factors, such as symptoms and ECG-abnormalities, increased cardiac screening and increased general awareness, may also play a role.