Registre Prospectif français Des Morts Subites Chez Des Sportifs Jeunes

Background:

The beneficial effects of moderate physical activity on health are well-established. However, it is also well-proven that intense sports participation increases the risk of cardiovascular events by 2.4 to 4.5 times before the age of 35 in individuals with known or unknown heart conditions. Sudden cardiac arrest (SCA), sometimes leading to sudden cardiac death (SCD), is the most dramatic event linked to sports.

Before the age of 35, sports-related SCA/SCD is rare, occurring in 0.7 to 2.7 per 100,000 athletes, which amounts to approximately 80 cases per year according to two French prospective studies. Despite its rarity, these events are often traumatic and highly publicized, presenting a significant public health and safety concern. Non-traumatic sports-related SCA/SCD is primarily of cardiovascular origin, irrespective of the level of sports participation. In most cases, SCA results from ventricular arrhythmia caused by known or undiagnosed arrhythmogenic cardiovascular disease, which varies by the victim's age. After the age of 35, atheromatous coronary artery disease accounts for 80-85% of cases. However, before the age of 35, a wider range of etiologies are observed. Arrhythmogenic genetic heart diseases-structural (e.g., arrhythmogenic right ventricular cardiomyopathy and hypertrophic cardiomyopathy) or non-structural (e.g., channelopathies)-are the most frequent causes. Congenital abnormalities, particularly anomalous connection of coronary artery, represent the second most common cause. Acquired heart diseases, such as fibrous scars (mainly post-myocarditis) and atheromatous coronary lesions, are less frequently involved. In this younger population, classical autopsy often fails to determine the cause in more than 40% of cases, leading to the term "sudden arrhythmic syndrome".

Few prospective studies have combined classical autopsy with systematic genetic analysis to identify the cause of SCA/SCD in the general young population, with no specific link to sports. One Australian study demonstrated the value of genetic testing, identifying a "clinically relevant" cardiac genetic variant for sudden death in 27% of cases. Moreover, the same pathology was identified in 13% of relatives of the victims who underwent clinical and genetic screening. Another small Swedish study (n=15), focusing specifically on channelopathies in cases of negative autopsies, revealed the disease in 40% of victims' families through genetic analysis.

Additionally, the role of acute or chronic toxic substance intake has been suggested, albeit without formal proof, as a factor promoting sports-related SCA/SCD. Toxicological screening is thus recommended as part of the etiological assessment. Including toxicological analysis alongside other etiological evaluations could help clarify the impact of illicit substances on sports-related SCA/SCD.