By Michael H. Crawford, MD, Editor

SYNOPSIS: A study of elite international soccer athletes of both sexes revealed women more often recorded what would be considered abnormal ECGs — only to return normal echocardiograms. This knowledge is especially valuable when treating those who have recovered from COVID-19.

SOURCE: Churchill TW, Petek BJ, Wasfy MM, et al. Cardiac structure and function in elite female and male soccer players. JAMA Cardiol 2021;6:316-325.

Normative values for ECGs and their corresponding echocardiographic features are lacking in elite soccer players. Churchill et al assessed ECG and echo data from the Fédération Internationale de Football Association (FIFA)-mandated screening exams for international competition for five seasons (2015-2019) in the U.S. men’s and women’s national soccer teams.

Athletes self-reported demographic data, including race and ethnicity. Interpreters were experts in reading athlete ECGs and were blinded to other athlete characteristics. ECG findings were compared to the echo results for each athlete. There were 122 women and 116 men included. Women were mainly white (71%), whereas men were evenly divided between white, Black, and Hispanic. Men reported a higher prevalence of normal training-related ECG findings than women: voltage criteria for left ventricular hypertrophy (LVH) 64% vs. 11% (P < 0.001), voltage criteria for right ventricular hypertrophy (RVH) 15% vs. 1% (P < 0.001), incomplete right bundle branch block 13% vs. 4% (P = 0.03), and early repolarization 84% vs. 29% (P < 0.001).

There were more abnormal ECG findings in women (11% vs. 0%; P < 0.001), the most common of which was pathologic T wave inversion (69%). Echo data showed men had higher wall thickness values, a higher LV mass index, and a higher LV end-diastolic volume (EDV) index. In 30% of women and 41% of men, wall thickness exceeded the upper limit of normal (9 mm and 10 mm, respectively). The maximum wall thickness observed was 13 mm in two men.

Echo showed most athletes living with either eccentric LVH or normal geometry. Indexed LV mass and EDV were above the upper limit of normal in most athletes. Mean LV ejection fraction (EF) was in the normal range in men and women, but 17 athletes recorded an EF < 55%. Diastolic function was normal in all athletes. None of the women with abnormal T waves on their ECGs showed any pathology on echo, but recorded higher LV mass indices compared to women with normal T waves (102 g/m2 vs. 90 g/m2; P = 0.02) and higher LVEDV indices (78 mL/m2 vs. 69 mL/m2; P = 0.03). The authors found a bicuspid aortic valve in four athletes, but none exhibited aortic enlargement. Also, none showed significant valve regurgitation or stenosis. The authors concluded abnormal ECG findings are more common in female athletes, and both men and women often record measures of LV size that exceed the upper limits of normal.

COMMENTARY

Distinguishing the effects of normal adaptive changes in LV and RV size as opposed to the effects of pathology on the ECG is important in screening athletes for participation in strenuous competitive sports. With the recognized effects of COVID-19 on the myocardium of some patients, this will become even more important now that many sporting activities are resuming. This report adds to the growing body of sport-specific changes in the ECG and echocardiogram. A major strength of this paper was the fact this was the largest population of elite female athletes reported to date. Also notable: Soccer is the most popular sport worldwide, and there have been several highly publicized cardiac arrest events during competition. Hence, FIFA has mandated ECG and echo screening for all those in international competitions. Although the study population here was relatively small, it represents elite athletes of both sexes who competed in five seasons.

The expected exercise training-related effects on the ECG, such as signs of chamber enlargement, were more common in men, whereas abnormalities usually associated with disease were more common in women. The rate of overtly abnormal ECGs in this study was 6%, but the rate in women was 12%. However, none of these women with abnormal ECGs showed any evidence of pathology on echo. Failure to recognize this would subject a significant number of female athletes to unnecessary false-positive testing. Most abnormal ECGs in women were T wave inversion in leads V1-V3, which usually is considered pathologic. The reason for this false-positive ECG pattern is unknown. Interestingly, four women with this finding on repeat ECG two years later recorded normal ECGs, yet they still were competitive at an elite level. Churchill et al also noted that in addition to sex, age must be considered. Adolescent athletes exhibited fewer ECG changes and less chamber enlargement than older athletes, which suggests the adaptation to athletic training is ongoing.

There were some limitations. Those with abnormal ECGs and normal echoes did not undergo further testing, such as MRI, nor did the group with EFs < 55%. It is possible at least some patients could have been living with an early or healing myocarditis. Also, these data are pertinent to elite athletes, but may not be translatable to non-elite sportsmen and women. In addition, the authors only saw serial data on a small subgroup, and there are no long-term follow-up data. Despite these limitations, this is a significant addition to our knowledge of the ECG and echo findings in well-trained, competitive athletes and especially that of female athletes.