The benefits of physical activity and regular exercise training for cardiovascular disease (CVD) prevention are widely described.1–3 However, sudden cardiac death (SCD), a tragic and highly visible event, may occur in apparently healthy athletes.1,2 Both sudden cardiac arrest (SCA) and SCD are the leading cause of death in young athletes during exercise.4 While coronary artery disease is the most common cause of SCD in veteran athletes (over 35 years), inherited cardiac conditions and sudden unexplained death (presumably electrical cardiac abnormalities) have been reported as predominant among younger individuals.1–3

Although the cases of SCD are relatively rare, its true incidence remains unknown, varying across the several studies, mainly due to the heterogeneity of the analyzed populations and methodological limitations.1,2,5 In fact, even the definition of “athlete” is controversial.1 These differences lead to a broad range of SCD incidence reported in athletes, between 0.1 and 13 cases per 100000 athletes per year.4 A study in from the United States that used a national college database, found an incidence of 1.9 per 100000 athletes per year.1 On the other hand, a prospective study in the Veneto region in Italy after the application of preparticipation screening programs, set an incidence of 0.4 per 100000 athletes per year.1,2 Also in Europe, a Danish national study reported an incidence between 0.47 and 1.21 per 100000 athletes per year and 6.64 per 100000 athletes per year, in people aged under and above 35 years, respectively.1 The study by Malhotra et al., on adolescent football players, reported an incidence of 6.8 per 100000 athletes per year.6 A state-of-the-art review settled on an incidence of 1:50000 in college athletes.5 To the best of our knowledge there are not studies addressing the incidence of SCD in athletes in Portugal.

Understanding these events, especially victims’ characteristics, risk factors, epidemiology, and sports circumstances is of the utmost importance to improve preventive strategies. In this context, improving preparticipation screening programs and especially emergency support and resuscitation conditions, with rapid initiation of cardiopulmonary resuscitation and automated external defibrillators, are essential measures.1,2

The aim of the current study was to evaluate the cases of SCD in athletes in Portugal over a 20-year period.

Between January 2003 and December 2023, a total of 42 SCD cases were identified. The athletes’ median age was 27 [18;42] years, ranging from 12 to 70 years, and 93% were male (only three cases occurred in women).

The distribution of SCD events according to sports modality is presented in Figure 1. Most of the cases occurred in outdoor sports (n=28; 67%), especially in football (n=13; 31%), athletics (n=4; 10%) and trail running (n=4; 10%). Among indoor sports, the cases were mainly reported in handball (n=3; 7%), futsal (n=3; 7%) and basketball (n=2; 5%). Furthermore, the majority of the SCD cases occurred during competitions or training sessions (n=27; 64%).

Figure 1.

Distribution of number of cases by sports modalities.

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The highest number of cases were reported in 2022 and 2021 (10 and 8, respectively), while in several years no events were found.

Figure 2 shows the incidence of SCD in Portugal during the period of analysis. The average yearly incidence of SCD was 0.39 cases per 100000 athletes, per year.

Figure 2.

Incidence of sudden cardiac death per year.

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The present study shows that the incidence of SCD in athletes in Portugal is very low. Although the methodology adopted was previously used in similar published studies based on retrospective analysis and passive data collection, it potentially underestimates the incidence calculation. On the other hand, and in line with the already known evidence, most of the reported SCD cases occurred in male athletes involved in outdoor sports and during competition or training sessions.

The most common methodologies used for the determination of SCD incidence in athletes are based on media searches, including professional press monitoring, retrospective registries, insurance claims, autopsy reports, death certificates, and national registries and databases.2,4,5 A brief advanced literature search performed in PubMed, using the mandatory terms “sudden cardiac death” and “athletes”, resulted in a total of 191 articles, of which 12 included media search in their methodology, as in our study. The characteristics of these studies are summarized in Table 1. Most were conducted in the United States of America, and the included populations were very heterogeneous. Furthermore, some studies only included events that occurred during or within one hour of sports, while others also included SCA.7,9,11–16 Consequently, SCD incidence ranged between 0.02 and 2.6 per 100000 persons per year.10,16

In fact, a media search underestimates the number of counted cases included in the incidence calculation. Studies from the United States addressing this issue found that media database reports identified 70% and 56% of the SCD events.2 In a study performed in Denmark, a media search identified only 20% of the SCD cases.5 In the setting of registries, correct completion has several biases, while insurance claims appear to miss even more cases.5 Confounders include the definition of an athlete, the total number of athletes at risk used to calculate the SCD incidence, and the baseline characteristics (i.e., age, sex, comorbidities).2,5 Even the definition of SCD is controversial; in some studies it includes all cases, while in others, only the deaths during and within one hour of sports or also SCA cases.17 According to European guidelines, SCD is defined as a sudden death presumed to be cardiac, occurring within one hour of symptoms or within 24 hours of being seen alive.18 Our study included all the presumed sports-related SCD in athletes, but not the SCA cases.

An Italian internet-based study analyzed both competitive and non-competitive athletes, defining the former as individuals participating in organized teams or engaging in regular competition against others, requiring systematic training.17 This study found higher rates of SCD in football and athletics, and mostly during or immediately after practice (51% and 9.2%, respectively), in line with our results.17 Studies from the United States report a higher incidence in Black athletes, three times the risk of white athletes, a variable not available in our study, and in basketball players.2,7–11 These differences in sports disciplines, football in Europe and basketball in United States of America, could be explained by the regional disparities in the most frequent national sport. In a prospective French study performed in the general population, but also including young athletes, a higher incidence of SCD was found in cycling, running, and football, which are the most common sports practiced in this country.15

The denominator of the incidence equation (number of athletes at risk), also needs to be precise.2,5 For example, an Italian study used data from both the Italian National Olympic Committee and the Italian National Institute of Statistics, while an American study performed in college athletes used various National Collegiate Athletic Association reports and databases.11,17 Our study relied only on the official online national records about the number of competitive athletes. More detailed data on this athletic population, both regarding demographic and exercise-related characteristics, is not available in Portugal.

The age of the athletes may also be a confounding factor because the incidence of SCD is higher in older individuals and many of these older deaths are unwitnessed.3,5 Our study found a wide range of ages (median of 27), from 12 to 70 years, with 75% occurring in those aged or under 42 years. This is in contrast to an Italian study that found 61.2% of cases in athletes older than 35 years, although they do not report the age range.17

In several studies, males have three to five times a higher incidence of SCD.2 This is in accordance with our analysis, showing only three cases in women (7%), which is in line with other internet-based studies.10,11,14,17

The incidence of SCD is also highly variable across studies with methodologies including media search. An Italian research study reported an incidence of 0.47 per 100000 persons per year, in contrast with an Israel study that found an incidence of 2.6 per 100000 persons per year.16,17 In a Danish study the incidence of SCD in athletes was 1.21 per 100000 per year and a 20-year study in college athletes found an incidence of 1 per 63682 athlete-years, with a decrease over the study.11,13 While an American one-year study found 69 cases, the Fédération Internationale de Football Association (FIFA) Sudden Death Registry included 617 cases in football players during a five-year prospective study.9,14 Nevertheless, in our population, the incidence was even lower, roughly 0.39 cases per 100000 athletes per year, with a slight increase in recent years. These findings could be attributed to the variation of media attention over the years, the “agenda-setting effect”, and to the absence of mandatory reporting.10 Therefore, the development of appropriate mandatory prospective registries is needed for studying SCD cases. This fact should be a priority because the overall number of athletes is increasing in Portugal.

The incidence of SCD in competitive athletes in Portugal is very low, 0.39 cases per 100000 athletes per year, with 42 cases reported between 2003 and 2023. Most events occurred in males, involved in outdoor sports, and during competition or training sessions. Although the use of a previously tested search methodology, this incidence is probably underestimated. However, as there are no mandatory SCD reporting requirements in Portugal, there is no other method to identify these cases. Due to the limitations of this passive data collection, commonly used in studies about SCD in athletes, prospective registries are needed, with standardization of relevant data, especially regarding its etiology and circumstances. Understanding these events may help to identify high-risk groups of athletes and to improve preventive strategies.

During the preparation of this work the author(s) used ChatGPT 3.5 in order to correct grammar errors. After using this tool/service, the author(s) reviewed and edited the content as needed and take(s) full responsibility for the content of the publication.

The authors have no conflicts of interest to declare.