Sports-Related Sudden Cardiac Arrest: Key Differences Identified

Regular physical activity is associated with a lower risk of cardiovascular disease and death. However, the risk of an acute cardiac event increases transiently during and immediately after intense activity, creating the so-called exercise paradox .

Sports-related sudden cardiac arrest (SrSCA) in young competitive athletes (under 35 years of age involved in competitive sports) has always received considerable media and community attention. However, recent reports have suggested that most SrSCAs occur in a recreational, rather than competitive, setting. Although the epidemiology of sudden cardiac death (SCD) in general (not just sports-related) has been described among children and young adults in the community, no studies have focused on SrSCA (including surviving cases) in young adults.

Etiologies among young victims in the general population (participating in recreational sports activities) could be different, especially considering that the proportion of ST-segment elevation myocardial infarction in young adults has increased considerably in recent years.

In the present work, the findings of a prospective study carried out in two countries are reported with the objective of determining the circumstances, characteristics and causes of SrSCA and identifying the main influencing factors for survival.

Prospective observational cohort study of all cases of SrSCA between 2012 and 2019 in Germany and the Paris area (France) with subjects aged 18 to 35 years. Detection of SrSCA was achieved through multiple sources, including emergency medical services (EMS) reports and web-based assessment of press releases. Cases and etiologies were centrally adjudicated.

Sports-related sudden cardiac arrest was defined as out-of-hospital cardiac arrest of suspected cardiac origin, occurring during competitive or recreational sports activities or within one hour of cessation of activity.

Sports-related sudden cardiac death (SrSCD) was defined as a sudden death of presumed cardiac cause occurring during or within one hour after cessation of competitive or recreational sports activities.

A total of 147 SrSCAs occurred (mean age 28.1 ± 4.8 years, 95.2% men), with an overall burden of 4.77 [95% confidence interval (CI) 2.85–6.68 ] cases per million years, including 12 (8.2%) cases in young competitive athletes.

While bystander cardiopulmonary resuscitation (CPR) was initiated in 114 (82.6%), bystander use of automated external defibrillators (AED) occurred in only a minority (7.5%). Public AED use before EMS arrival (odds ratio 6.25, 95% CI 1.48–43, 20 p = 0.02) was the strongest independent predictor of survival to hospital discharge (38.1% ).

Among cases that benefited from both immediate bystander CPR and AED use, the survival rate was 90.9%. Coronary artery disease (CAD) was the most common etiology (25.8%), mainly due to acute coronary syndrome (86.9%).

This first comprehensive evaluation of SrSCA in the general population of young adults aged 18 to 35 years revealed a more frequent occurrence in recreational sports participants than among elite athletes, with a striking male predominance. Although almost always witnessed, the rate of AED use by bystanders was disappointingly low. This is important, as AED use clearly improves survival.

Coronary artery disease was found to be the most common underlying cause of young SCAr despite the young age of the participants, underscoring the need for targeted cardiovascular risk assessment/prevention in young people. Finally, the very low autopsy rates, as well as the low rate of genetic testing in SrSCA survivors with a structurally normal heart, combined with the significant number of undiagnosed cases represent an important missed opportunity to establish etiology and prevention in relatives of first grade.

Most cases of SrSCA occur in recreational sports participants rather than competitive athletes, contrary to what the general public may perceive. This was previously observed in all SrSCA participants where the mean age was higher. However, this does not necessarily mean that the risk of SrSCA is lower in elite athletes, but rather that the number of participants in recreational sports is much higher.

The increased overall risk of SCD in men could be based on (a) gender differences in vulnerability to arrhythmic substrates, (b) the higher prevalence of coronary heart disease (CHD) and myocardial ischemia among men (CAD not was found among female victims in this study), (c) the most frequent exposure to the triggering effect of high-intensity exercise (men have a greater cumulative exposure to vigorous sports, and the greatest risk of SCD during an episode of exertion vigorous is much less pronounced among women), (d) the fact that the relative risk of exercise-induced SCD is dose-dependently reduced by habitual exercise less markedly among men compared to women, ( e) hormonal influences, including that of circulating estrogens.

The use of AEDs by bystanders was only carried out in a minority of cases.

This is extremely important, given that early AED use was the strongest determinant of survival , with ≥90% at hospital discharge in the subgroup of subjects who benefited from both early CPR and defibrillation.

The data also highlight that CHD was the most important etiology observed in this young group, predominantly as single-vessel disease affecting the left anterior descending artery. Acute coronary syndrome with a clearly identifiable culprit lesion was the primary mechanism, indicating that shear forces induced by physical activity could have induced plaque rupture through increased vascular wall stress.

The fact that young subjects with CHD were unaware of the underlying condition and generally maintained physical activity despite having chest pain (showing a lack of awareness of symptoms) could help explain why SCD often It may present as the first manifestation of ECC in young individuals participating in recreational activities.

In the present study, smoking and obesity were prevalent as modifiable cardiovascular risk factors, and substance abuse (including cannabis or amphetamines) was observed in three subjects with SCD. The results suggest that the epidemiology of CHD in young people may be changing with the need to improve primary prevention.

Hereditary cardiomyopathies were the next most common underlying cause of SrACS after CHD. Genetic differences between populations in different geographic regions may result in a variable contribution of cardiomyopathies to SrSCA.

> Limitations: Although this was a prospective registry, the cause of death could not always be determined with certainty in all cases. This is a universal limitation in SCD studies, particularly when individuals die in the field or immediately after hospital admission, preventing further diagnostic investigation. Autopsies and genetic testing were rarely performed.

Among young adults in the general population, SrSCA occurred primarily in recreational sports participants rather than competitive athletes, with a marked male predominance.

Although survival to discharge can reach 90% among those who benefit from both CPR and early defibrillation, the use of publicly available AEDs was very low despite the frequent presence of bystanders.

Coronary artery disease is the most common cause of SrACS, underscoring the need for targeted cardiovascular risk assessment/prevention in young people. The low autopsy rates, as well as the low rate of genetic testing in SrSCA survivors without a clear diagnosis, represent an important missed opportunity.

The study highlights the need for better education of athletes about warning symptoms, in the population about basic life support and the commitment of the medical society to establish a definitive diagnosis.