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............................................................................................................................................................................. SCD is defined as a sudden unexpected death due to a cardiac cause, or a sudden death in a structurally normal heart at autopsy with no other explanation for death and a history consistent with cardiacrelated death (i.e. requiring cardiac resuscitation).17,27,32 In order to compare previously reported data on SCA and SCD using variable definitions, the timing of the event should be categorized as occurring during the episode, within the first hour post-exercise, or between 1 to 24 h post-exercise.30 The activity at the time of the event can be further characterized as occurring during training or competition, at rest, or during sleep.30

Exercise-induced ACS are most likely to affect adult and senior athletes and result from atherosclerotic plaque disruption and coronary thrombosis in most cases.34,35 More than 50% of patients who experience acute MI (AMI) and SCA do not have pre-existing symptoms or a known history of CAD.36,37 In long-term endurance athletes, SCA and myocardial ischaemia can also occur from ‘demand’ ischaemia due to an imbalance between oxygen supply and demand resulting from stable calcified plaque and a fixed stenosis.38 In a study of United States (US) marathon and half-marathon races, none of the runners with SCA with serious (>80% coronary artery stenosis in a proximal left coronary artery or three-vessel disease) coronary atherosclerosis had angiographic evidence of acute plaque rupture or thrombus.38

3.4 Incidence of sudden cardiac death in

athletes Current estimates of the incidence of SCD in competitive athletes range from almost 1 in a million to 1 in 5000 athletes per year.17,39,40 Differences in current estimates are largely due to inconsistent study methodology and heterogeneous population comparisons. Because reporting of SCD in athletes is not mandatory in most countries, studies risk underestimating the true incidence due to incomplete case ascertainment. For instance, studies using media reports as their main source to detect incidents of SCD identify only 5 - 56% of cases, even in high-profile competitive athletes.4144 Similarly, use of catastrophic insurance claims as the only method for case identification missed 83% of SCD cases and 92% of all SCA cases in Minnesota high school athletes.40,45 The athlete population being studied also needs to be precisely defined. Census population statistics, cross-sectional surveys, and self-reported athlete participation data all produce less reliable calculations. Other study details should also be considered. Does the study include all cases of SCA (survivors plus deaths) or only SCD? Does the study include cases occurring at any time (i.e. during exercise, rest, or sleep), or only those that occur during sports? Studies indicate that 56 - 80% of SCA in young athletes occurs during exercise with the remainder non-exertional.17,18,46 Evidence supports that some athletes display a higher risk for SCA based on sex, race, or sport.17,40,41,4550 Incidence rates are consistently higher in male athletes than in female athletes, with a relative risk ranging from 3: 1 to 9: 1 (male: female).17,45,4749,51,52 Black athletes of African Caribbean descent also have a higher risk than white athletes. In US college athletes, males had a higher risk than females (1 in 38 000 vs. 1 in 122 000), and black athletes had a 3.2 times higher risk than white athletes (1 in 21 000 vs. 1 in 68 000).17 Male basketball players had the highest annual risk of SCD (1 in 9000), and male black basketball players had a risk of 1 in 5300.17 Based on available studies and a systematic review of the literature, a generally accepted annual incidence of all SCA is approximately 1 in 80 000 in high school-aged athletes and 1 in 50 000 in college-aged athletes.50 Male athletes, black athletes, basketball (US) and soccer (Europe) athletes represent higher risk groups. Limited estimates are available for youth, professional, and master athletes.

3.5 Aetiology of sudden cardiac death

during exercise SCD in young athletes is usually caused by a genetic or congenital structural cardiac disorder.1719,42,53,54 However, autopsy-negative sudden unexplained death (AN-SUD), also referred to as sudden arrhythmic death syndrome, is reported on post-mortem examination in up to 44% of presumed SCD cases depending on the study population.17,28,42,5356 In apparently healthy young athletes the prevalence of cardiac disorders associated with SCD is approximately 0.3%, and this figure is supported by multiple studies using non-invasive evaluation tools to detect cardiac disorders at elevated risk of SCD.20,5765 In athletes >35 years of age, more than 80% of all SCD is due to atherosclerotic CAD, and vigorous physical exertion is associated with an increased risk of AMI and SCD.34,6670 The athletes at greatest risk are those with little or no background in systematic training.

3.6 Screening modalities for

cardiovascular disease in young athletes Most experts believe that early detection of potentially lethal disorders in athletes can decrease CV morbidity and mortality through risk stratification, disease-specific interventions, and/or exercise modifications.22,57,58,71 CV screening by history and physical examination or by electrocardiogram (ECG) presents unique challenges and limitations. Several studies have documented the low sensitivity and high positive response rate of pre-participation history questionnaires.64,65,7275 In CV screening studies in which experienced clinicians use contemporary ECG interpretation standards, ECG screening outperforms history and physical examination in all statistical measures of performance.58,59,62,64,65,74,76 While echocardiography may identify additional structural disorders, there is insufficient evidence to recommend an echocardiogram for routine screening.77

3.7 Screening for cardiovascular disease

in older athletes The recommendations and evidence base for CV screening in athletes >35 years of age are limited. CV screening in adult and senior athletes must target the higher prevalence of atherosclerotic CAD. However, routine screening for ischaemia with exercise testing in asymptomatic adults has a low positive predictive value and a high number of false-positive tests and is not recommended.7880 A screening ECG may still discover undiagnosed cardiomyopathies and primary electrical disorders in older athletes, and risk factor assessment for CVD may identify higher risk individuals who warrant additional testing. Thus, consistent with a 2017 ESC position paper on pre-participation CV screening, exercise ECG testing should be reserved for symptomatic athletes or those deemed at high risk of Downloaded from academic.oup.com/eurheartj/article/42/1/17/5898937 by guest on 07 October 2026