Current conflict

Protagonist: Routine screening of all athletes prior to participation in competitive sports should be mandatory to prevent sudden cardiac death

The frequency of SCD occurring in athletes during organized competitive sports reported in different series in the literature varies as a function of athletes’ gender and age, with a striking male predominance (male-to-female ratio 10:1) and a significant upward trend with increasing age.1, 2, 3, 4 In apparently healthy adult (>35 years) joggers or marathon racers, the estimated rate of sports-related fatalities ranges from 1:15,000 to 1:50,000.⁸ In comparison, the prevalence of fatal events in high school and college athletes (age range 13–24 years) in the United States has been estimated in retrospective analyses to be <1:100,000 participants per year.⁹ A prospective population-based study in Italy reported an incidence rate of 3:100,000 young competitive athletes (age range 12–35 years) per year.¹⁰ The higher mortality rates among Italian competitive athletes can be explained by the older age (mean age 23 vs 16 years) and the higher proportion of men (82% vs 65%) compared to US athletes.

The vast majority of athletes who die suddenly have previously unsuspected structural heart diseases.1, 2, 3, 4, 5 The causes of SCD reflect the age of participants. In older athletes (adults >35 years), atherosclerotic coronary artery disease accounts for the vast majority of fatalities. In young athletes, there is a broad spectrum of cardiovascular substrates, including congenital and inherited heart disorders. Cardiomyopathies have been consistently implicated as the leading cause of sports-related cardiac arrest in the young, with hypertrophic cardiomyopathy accounting for more than one third of fatal cases in the United States¹ and arrhythmogenic right ventricular cardiomyopathy/dysplasia for approximately one fourth in Italy.2, 4, 5

An Italian prospective study demonstrated that adolescent and young adults involved in sports activity have a 2.8 times greater risk of SCD than their nonathletic counterparts.¹⁰ However, sports itself is not the cause of the enhanced mortality; rather, it triggers cardiac arrest in athletes who are affected by cardiovascular conditions, such as cardiomyopathies, premature coronary artery disease, and congenital coronary anomalies, which predispose to life-threatening ventricular arrhythmias during physical exercise. This finding reinforces the need for systematic evaluation of adolescent and young individuals embarking on sports activity in order to identify those with potentially lethal cardiovascular diseases and to protect them against the increased risk of SCD.

Italy is the only country in the world where preparticipation evaluation is required by law. A mass screening program, essentially based on 12-lead ECG, has been the practice for almost 25 years (Figure 1).5, 6 This population-based, long-term experience has provided compelling evidence of screening efficacy in identifying athletes at risk for SCD and in preventing SCD.

SCD during sports is most often the first clinical manifestation of an underlying cardiovascular disease, which usually is clinically silent. This explains why a screening protocol based solely on the athlete’s history and physical examination (without 12-lead ECG), as used in the United States, is of limited value.1, 7 The long-term Italian experience has demonstrated that 12-lead ECG in addition to history and physical examination is a sensitive and powerful tool for identification and risk stratification of athletes at risk for SCD, and that systematic preparticipation screening using ECG is a lifesaving strategy.

The Italian preparticipation evaluation has been proved to successfully detect athletes with previously undiagnosed hypertrophic cardiomyopathy, which is the leading cause of athletic-field fatalities in young competitors.⁵ We reported that among 33,735 athletes undergoing preparticipation screening at the Center for Sport Medicine in Padua, 22 (0.07%) showed definitive evidence, both clinical and echocardiographic, of hypertrophic cardiomyopathy. An absolute value of screening sensitivity for hypertrophic cardiomyopathy cannot be derived from this study because systematic echocardiographic data were not available. However, the 0.07% prevalence of hypertrophic cardiomyopathy found in the white athletic population of the Veneto region of Italy, evaluated by history, physical examination, and ECG, is similar to the 0.10% prevalence reported for young white individuals in the United States, as assessed by echocardiography. This finding indicates that the Italian screening, which is essentially based on 12-lead ECG, may be as sensitive as echocardiographic screening in detecting hypertrophic cardiomyopathy in the young athletic population. These results were confirmed by Pelliccia et al.¹¹ In their study, 4,450 members of Italian national teams, initially judged eligible for competition as a result of Italian baseline systematic preparticipation screening (i.e., history, physical examination, and 12-lead ECG), subsequently underwent clinical and echocardiographic examination at the Institute of Sports Sciences in Rome to assess for the presence of undetected hypertrophic cardiomyopathy. None of the 4,450 athletes showed evidence of hypertrophic cardiomyopathy. This study further demonstrates that Italian national preparticipation screening programs, including 12-lead ECG, is efficient in identifying athletes with hypertrophic cardiomyopathy, and that echocardiography does not increase screening sensitivity.

As shown in Table 1, 12-lead ECG offers the potential to detect (or to raise clinical suspicion of) lethal conditions (other than hypertrophic cardiomyopathy) that manifest as ECG abnormalities, such as arrhythmogenic right ventricular cardiomyopathy, dilated cardiomyopathy, long QT syndrome, Lenègre disease, Brugada syndrome, short QT syndrome, and Wolff-Parkinson-White syndrome. Overall, these conditions (including hypertrophic cardiomyopathy) account for up to 60% of SCD in young competitive athletes. A number of these conditions were discovered only recently, so diagnosis at preparticipation screening is increasing over time.12, 13

The possibility of detecting either premature coronary atherosclerosis or anomalous coronary artery in young competitive athletes is limited by the scarcity of baseline ECG signs of myocardial ischemia. However, we reported that approximately one fourth of young athletes who died of coronary artery diseases had warning symptoms and/or ECG abnormalities at preparticipation screening that could raise the suspicion of cardiac disease.⁵

Of note, none of the 22 young athletes with hypertrophic cardiomyopathy in the Padua country area who were identified by preparticipation athletic screening and were disqualified from training and competition died during an average 8-year follow-up period.⁵ This favorable long-term outcome of former athletes with hypertrophic cardiomyopathy was the result not only of restriction from competitive sports activity but also of the subsequent close follow-up and clinical management aimed at preventing SCD. These findings indicate that preparticipation screening not only changed the mode of death from exercise related to exercise unrelated but actually reduced mortality from hypertrophic cardiomyopathy.

We recently reported the results of a time-trend analysis of the changes in incidence rates and causes of SCD in young athletes age 12–35 years in the Veneto region of Italy between 1979 and 2004.¹⁴ This time-trend analysis confirmed and extended our previous observations in athletes with hypertrophic cardiomyopathy by demonstrating that sudden death mortality from any cardiovascular cause declined in athletes sharply after the introduction of a nationwide screening program in 1982. Fifty-five SCDs occurred in screened athletes (1.9 deaths per 100,000 person-years) and 265 deaths in unscreened nonathletes (0.79 deaths per 100,000 person-years). The annual incidence of SCD in athletes decreased by approximately 90%, from 3.6 per 100,000 person-years in 1979–1980 to 0.4 per 100,000 person-years in 2001–2004, whereas the incidence of SCD in the unscreened nonathletic population did not change significantly over that time (Figure 2). The decline in death rate started after mandatory screening was launched and persisted to the late screening period. Compared with the prescreening period (1979–1981), the relative risk of SCD was 44% lower in the early screening period (1982–1992) and 79% lower in the late screening period (1993–2004). Most of the reduced death rate was due to fewer cases of SCD from cardiomyopathies. Over the same time interval, we performed a parallel study that examined trends in cardiovascular causes of disqualification from competitive sports in 42,386 athletes undergoing preparticipation screening at the Center for Sports Medicine in Padua. We found that the decline in mortality from cardiomyopathies paralleled the concomitant increase in the number of athletes with cardiomyopathies (both hypertrophic and arrhythmogenic right ventricular cardiomyopathy) who were identified and disqualified from competitive sports over the screening periods at the center.

Screening of large athletic populations has a significant socioeconomic impact. Strategies for implementing population-based screening programs depend on the particular socioeconomic and cultural traditions as well as the specific medical systems in place in different countries. However, the long-term Italian experience indicates that screening is made feasible because of the limited costs in the setting of a mass program. The cost of performing a preparticipation cardiac history/physical examination by qualified physicians has been estimated to be 20 Euro per athlete and rises to 30 Euro per athlete if a 12-lead ECG is added.⁶ The screening cost is covered by the athlete or by the athletic team, except for athletes younger than 18 years, for whom the expense is supported by the National Health System.

The cost of further evaluation of athletes with positive findings at first-line examination is smaller than expected based on the presumed low specificity of 12-lead ECGs recorded from athletes. In our experience with 42,386 athletes initially screened by history, physical examination, and 12-lead ECG, 3,914 (9%) were referred for further examination, and 879 (2%) ultimately were disqualified for cardiovascular reasons.¹⁴ Therefore, the percentage of false-positive results (i.e., athletes with a normal heart but positive screening findings) requiring additional testing, mainly echocardiography, was 7%, with a modest proportional impact on cost.

Costs of infrastructure and training courses for preparticipation screening must be considered. Athletic evaluation should be performed by a physician who has the specific training, medical skill, and scientific background to reliably identify the clinical symptoms and signs associated with the cardiovascular diseases responsible for exercise-related SCD. In Italy, physicians primarily responsible for preparticipation screening and determination of eligibility for competitive sports attend postgraduate residency training programs in sports medicine (and sports cardiology) on a full-time basis for 4 years. These specialists work in sports medical centers specifically devoted to periodic evaluation of athletes.

Disqualification of athletes could be associated with additional costs in terms of athletes’ health, satisfaction, and even future opportunities, including professional activity. However, the increased risk of SCD, worsening disease, or both associated with athletic training and competition in the setting of known cardiovascular disorders is a controllable factor, and the devastating impact of even infrequent fatal events in the young athletic population justifies appropriate restriction from competition.¹⁵