Were athletes at increased risk of sudden cardiac death and survived sudden cardiac arrest in 2021?

In a letter dated December 2022, Polykretis and McCullough reported that there had been an increase in sudden cardiac death (SCD) and survived sudden cardiac arrest (SCA) among athletes from 2021 until the date the letter was submitted.1 In the letter, they cited a database purportedly containing 1598 instances of athletes having experienced SCA or SCA during the mentioned timeframe.2 When I examined the database, however, I did not find support for the claim. A number of the cases in the database were unrelated to elite sports as well as SCD or SCA. For example, in some cases, the stated cause of death was suicide. In a different instance, a 70-year-old man reportedly experienced SCD while cycling. The referenced database was clearly disorganized and did not provide evidence of the stated claim. Whether or not there was an increase in SCD and SCA has been the subject of considerable debate, but as far as I am aware no scientific investigation has been conducted.3 This prompted me to look further. In the letter, Polykretis and McCullough compared the data with a systematic review by Bille, Figueiras, Schamasch, et al, who reported that from 1966 to 2004, a total of 1101 athletes under the age of 35 had died as a result of various heart-related conditions. However, such a broad comparison may not be the best approach for assessing whether athletes were at an increased risk of SCA and SCD in 2021 in comparison with pre-COVID data. I would argue that a more appropriate comparison can be drawn if we exclusively focus on cases of SCA and SCD among elite footballers, as this subject has been extensively studied. As elite footballers are in the media spotlight, cases of SCA and SCD are unlikely to be overlooked. Cases occurring at recreational and competitive levels are less likely to receive significant media coverage or be recorded by surveillance systems. The pre-COVID rate of SCA and SCD among footballers was assessed in a prospective, observational study by Egger et al4 known as the FIFA study. Globally, the study found a total of 617 cases of SCD and SCA from 2014 to 2018. A total of 475 died. The study also included a few cases from related sports, including beach soccer, walking football, and futsal. Out of the 617 cases, a total of 95% occurred at the amateur level, which encompassed both recreational and competitive players. It only found 33 cases classified as elite level, amounting to 6.6 cases per year on average. The study was confined to cases during football-specific exercise, such as during training or a match, or within 1 h after cessation of such activity. In the context of this letter, let x denote the number of cases of SCD and SCA in 2021, that is, 10 cases, and let x! = 1 × 2 × 3 × 4 × … × x. Further, let λ be the average rate, namely 6.6 cases. Euler's constant, e ≈ $$ \approx $$ 2.71828. It can easily be shown that the 10 cases are not statistically significant, that is, P X ≥ 10 = 0.131 > 0.05 = α $$ P\left[X\ge 10\right]=0.131>0.05=\alpha $$ , where α is the significance level. It should be pointed out that the data are preliminary and surveillance systems might have picked up additional cases. Furthermore, two potentially relevant cases were excluded due to insufficient corroborating information. If there had been 12 cases or more, then P < 0.05. If evidence eventually emerges that a non-coincidental surge in SCD and SCA took place in 2021, a number of potential causes should be considered. First, as entire football leagues were put to a standstill for long periods in 2020 as a result of lockdowns and restrictions, it is likely that there were significantly fewer cases than the average. If this happened, the cases that under normal circumstances would have taken place in 2020 could have been postponed to 2021, resulting in an increase. Alternatively, myocarditis, which is a major cause of sudden, unexpected death in young adults, may have been induced via a SARS-CoV-2 infection or via mRNA SARS-CoV-2 vaccination. It is well documented that post-viral myocarditis can result in SCD in athletes. However, to my knowledge, there have been no reported cases associated with SARS-CoV-2.5 With respect to vaccination, it should be mentioned that an autopsy-based histopathological characterization of myocarditis found that “myocarditis can be a potentially lethal complication following mRNA-based anti-SARS-CoV-2 vaccination”.6 Moreover, an endomyocardial biopsy-proven case series found that 9 out of 15 patients had detectable spike protein on cardiac myocytes.7 As there was no detectable nucleocapsid protein, it was concluded to be spike protein associated with mRNA SARS-CoV-2 vaccination. The patients had all been diagnosed with myocarditis following vaccination. All in all, the data suggested that myocarditis came about due to an autoimmunological response that had been triggered by the formation of the spike protein within the heart. Supporting these conclusions, a case study in Perfusion found that mRNA SARS-CoV-2 vaccination-induced fulminant myocarditis has a “high morbidity and mortality”.8 In discussing possible serious adverse events associated with SARS-CoV-2 mRNA vaccination, it is important to balance these with findings from randomized clinical trials, observational studies, and reviews.9-12 Health authorities and regulatory agencies have assessed that the health-beneficial effects associated with vaccination outweigh the risks. I encourage researchers to study the topic in greater depth and determine the exact number of cases in 2021 and beyond. In conclusion, I thank Polykretis and McCullough for advancing the discourse on the important subject of SCA and SCD in athletes. Daria Joackim Kato assisted with finding cases of SCA and SCD. Caroline Cheruiyot proofread the manuscript. The author declares that he has no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.