INTRODUCTION

Sudden cardiac death (SCD) in athletes, although rare, is a tragic event that not only affects the athlete’s family but also those around the athlete, including friends, teammates, and many others in the community. Although the benefits of exercise are well known, athletes who are involved in regular intensive exercise are at a higher risk of SCD than nonathletes (1,2). The most common causes of SCD in nonathletes are coronary artery disease and channelopathies (3), whereas some of the most commons etiologies of SCD in young athletes include hypertrophic cardiomyopathy, idiopathic left ventricular cardiomyopathy, Wolff-Parkinson-White syndrome, arrhythmogenic right ventricular cardiomyopathy, and long QT syndrome (4). Most of these cardiac conditions can be identified on an electrocardiogram (ECG), but due to the many physiologic adaptations seen on the well-­conditioned heart, the interpretation of an ECG can be challenging and can mistakenly be interpreted as abnormal (5,6). Over the last decade, physicians in the sports medicine and cardiology fields addressed these issues by creating standardized guidelines for interpreting ECGs in athletes and evolving by distinguishing the physiological from pathological ECG changes. Several documents of ECG standards exist as developed by several organizations, including the 2010 European Society of Cardiology guidelines, the 2013 Seattle Criteria, the 2014 Refined Criteria, and, most recently, the 2017 International Criteria (5,7,8). Studies compared the International Criteria to older guidelines and consistently show that the International Criteria have reduced both the total abnormal and false-positive ECG rates while also demonstrating high specificity and sensitivity (5–7). The most significant update in the International Criteria involves the inclusion of a “yellow” category (i.e., borderline or unclear risk) ECG results. This category indicates instances where 2 or more borderline findings necessitate further assessment (Figure 1) (8).

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Most SCD cases are due to previously undiagnosed and asymptomatic cardiovascular disease (1). Researchers and physicians contend that use of a resting ECG may provide clues in asymptomatic athletes that may decrease SCD risk. Asif et al. (9) reported a major reduction in the incidence of SCD in young high school, college, and professional athletes after the implementation of ECGs in preparticipation sport screening (PPE). This practice is now widely used in European countries as a preliminary screening for indicators of SCD (1,2). The use of ECG screening is incorporated as a part of PPE and is also mandated in countries including Italy and the United Kingdom (2). In Europe, several researchers and physicians have come to the consensus that incorporating and interpreting ECGs using the International Criteria has resulted in a decrease in the number of false-positive tests, a higher accuracy in interpretation, a decrease in SCD in young athletes, and medical cost savings (2,9,10). In the United States, the American Academy of Family Physicians, the American Academy of Pediatrics, and the American Heart Association recommend screening athletes using a PPE to identify previously undiagnosed heart conditions (11). However, the universal use of ECG in PPE is controversial due to cost-projection models suggesting that replicating the European strategy of ECG screening in the United States would result in enormous costs per life saved (12–14).

Each year the Andrews Institute’s Sports Medicine Outreach program and Baptist Health Care in Pensacola, Florida, provide required physicals to student athletes in local partner schools in Escambia, Santa Rosa, Okaloosa, and Walton counties. This PPE includes assessments of height, weight, vision, and blood pressure and a physical examination. To enhance these health screenings for high school student athletes, ECGs were added to the PPE during the 2022 outreach event. Although ECGs are not required by the Florida High School Athletic Association or in the aforementioned counties, research suggests that they may increase the likelihood of identifying cardiac conditions that pose a higher risk of a cardiac event or cardiac arrest during athletics (1,2,5). The purpose of this study was to document the efficacy of implementing ECGs and to highlight the cardiac abnormalities identified in high school student athletes tested during the 2022 1-d PPE screening event in Florida.

METHODS

RESULTS

In total, 1,357 high school and middle school athletes were screened. The athletes were 65% male (n = 884) and overall participated in 16 different sports (Table 1). Ages ranged from 13 to 18 years. Race and ethnicity were self-reported and consisted of predominantly white and black athletes (∼84% combined), along with Hispanic, Asian, Pacific Islander, Native American, and other race athletes. Information on race and ethnicity was not available for 10 participants. The sports with the highest number of athletes were football, followed by soccer, basketball, and volleyball.

TABLE 1. Population demographics.

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ECG With Normal Physiological Cardiac Adaptations

Borderline abnormalities according to the International Criteria observed in the young male athletes were left and right axis deviation and left atrial enlargement. Female athletes had a significantly higher rate of left atrial enlargement, tachycardia, and ST depression than male athletes (P < 0.05; Table 2). Male athletes had a significantly higher rate of left ventricular hypertrophy, bradycardia, ST elevation, left and right axis deviation, and early repolarization (P < 0.05; Table 2) than female athletes. These borderline abnormalities were observed in isolation, and all athletes were asymptomatic; therefore, no further evaluation was required, and those athletes were cleared to participate in sports. Table 3 reports the distribution of ECG characteristics by race and ethnicity.

TABLE 2. Sex differences in the electrocardiogram screening of young high school athletes.

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TABLE 3. Ethnicity differences in the electrocardiogram screening of young high school athletes.

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DISCUSSION

Abnormal ECGs were present in 1.7% of the athletes. Only 3 athletes (0.2%) were identified with cardiac conditions associated with SCD risk, and all 3 were asymptomatic. Neither family history nor physical examination detected these ECG conditions. A similar study by Drezner and colleagues (15) found ECG abnormalities in 22 out of 790 college athletes (2.8%), 5 asymptomatic athletes (0.6%) were identified with conditions associated with SCD, and 4 athletes had a normal physical examination. In a recent study in the United States, Harmon et al. (16) suggested that incorporating an ECG alongside a physical examination increases the likelihood of detecting a cardiovascular condition associated with SCD 6-fold compared with relying solely on a physical examination. Furthermore, these authors asserted that combining an ECG with a physical examination enhances cost efficiency per diagnosis 5-fold (16). A limitation of our study is that we were not able to determine the cost of incorporating ECGs into the PPE.

Training-related cardiac adaptations or “athlete’s heart” were observed in the majority of the high school athletes in the present study. These training-related adaptations are like those found in other studies (17–20). It is worth mentioning that in the current study, female athletes had a significantly higher incidence of ST depression, specifically in leads V5 and V6, without T wave inversion. Harris and colleagues (17) reported that isolated ST depression up to 0.03 mV is a normal variant in female athletes based on similar observations. Sinus tachycardia was observed in a higher number of female athletes. Most of these female athletes (73.1%) were between the ages of 14 and 16 years old. Harris and colleagues (17) reported that young female athletes exhibit higher resting hear rates than male athletes.

Similar to a study by Halasz (18), sinus bradycardia, a common training-related abnormality, was observed in the majority of white male athletes. Additionally, our study revealed that the most common training-related ECG patterns in young males was left ventricular hypertrophy (69.9%) and early repolarization (44.5%) with QRS-ST junction elevation (48.3%). It is well known that common training-related changes in athletes’ hearts are attenuated vagal tone and/or increased cardiac mass (19). A recent study by Forsa et al. (20) stated that athletes experience cardiac remodeling beyond the reference often by age 12, with a majority being young males who have left ventricular hypertrophy. Similarly, Abela and Sharma (19) stated that left ventricular hypertrophy is common in male athletes. Additionally, Abela and Sharma (19) stated that ST segment elevation in the right precordial leads is present in 45% of white and 90% of black athletes. In the present study, ST segment elevation was observed in black and white male football and basketball players. Early repolarization is a common finding in young athletes. Abela and Sharma (19) reported that early repolarization accompanied by ST segment elevation is found in 25% of white athletes and in up to 40% of black athletes. In support of these previous findings, our study revealed that 46% of black athletes exhibited early repolarization, whereas the prevalence among white athletes was 25%.

This study presents various limitations that warrant acknowledgment. First, 6 athletes with abnormal ECGs opted not to undergo further evaluation, preventing the determination of whether their ECG abnormalities were indicative of an actual health concern or merely a physiological adaptation to exercise. Second, the study did not quantify the monetary value or assess the overall cost of the project, including factors such as time, personnel, and equipment. Consequently, the cost-effectiveness of the endeavor could not be ascertained. Third, the genetic and genealogical ancestry of the high school athletes was not established, meaning that the heritage of these young athletes and their relationship with the ECG diagnosis remained unknown. Consequently, the study’s outcomes may lack generalizability to the broader population due to this unexplored aspect of the participants’ backgrounds.

CONCLUSION

This study demonstrated that most young athletes screened with an ECG during a 1-d PPE displayed normal physiological adaptations to exercise or an “athlete’s heart.” However, 3 athletes (0.2%) were diagnosed with cardiac conditions linked to SCD. Notably, all 3 athletes were asymptomatic, and neither family history nor physical examination detected these SCD-associated conditions. The study’s findings align with other research indicating that properly interpreted ECG screening contributes to the identification of pathological conditions associated with SCD (5,15,16). However, it is essential to recognize that although using ECGs as a screening tool for SCD in athletes appears effective in identifying those at risk, several factors require consideration. Institutions with adequate resources can undertake more comprehensive and costly cardiovascular screening facilitated by an ample number of volunteers or workforce for execution. The accurate interpretation of athletes’ ECGs requires both practice and professional experience (21). Variability exists in physician expertise, cardiology support, volunteer availability, and resources across institutions, posing challenges or even rendering the successful and accurate implementation of ECG screening difficult in some cases (21). Therefore, the feasibility of integrating ECGs into preparticipation screening, considering testing, time, and resource requirements, presents a significant challenge that necessitates thorough evaluation before implementation. Finally, it is noteworthy that, to our knowledge, this study signifies the highest number of athletes screened in a single day.