Most young people aged 13 to 14 years are in good health. Sudden cardiac death (SCD) is rare among these individuals but has a considerable social impact. The main causes of SCD reported in persons younger than 35 years are channelopathies and structural heart disease, particularly arrhythmogenic right ventricular dysplasia and hypertrophic cardiomyopathy.1–3 Heart disease leading to SCD among young people tends to progress with no prior symptoms and remains unnoticed until the fatal event, making early screening necessary.4

Cardiovascular screening of a healthy population based on a resting electrocardiogram (ECG) has aroused considerable debate,5,6 but no international consensus has been reached on recommended testing. There is only scant evidence in healthy young populations, and ECG screening programs in young people based on obsolete ECG criteria have shown little success in detecting underlying heart disease, hindering an assessment of cost-effectiveness in this population group.7,8

In Spain, experience with ECG screening is limited to soccer players9 and elite athletes,10 in whom the instrument has proven to be cost-effective.11,12 The European Society of Cardiology (ESC) published its initial recommendations for ECG interpretation in athletes in 200513 and has issued several updates by 201714-16 to lower the number of false-positive results.

The aim of the present study was to identify ECG changes in a young, asymptomatic, apparently healthy population to correlate pathologic ECG findings with a possible early diagnosis of underlying heart disease.

In all, 1911 students (79% of 2424 enrolled students) participated in ECG screening (Figure 1). A total of 254 students (92% participation) were studied in 2010, the year with the highest percentage, whereas only 61% (n=162) participated in 2015. The reasons for nonparticipation were unknown. The mean age of participants was 14 years. A total of 50.3% were girls. As of 2014, the mean height (163±8cm), mean weight (55±11kg), and mean body mass index (20.6±4) were also recorded. Information was also obtained on students’ regular physical activity: 48% of the population was sedentary. Soccer (n=167) was the most common regular sport. A total of 66% of the population had not undergone resting ECG before screening.

Figure 1.

Study flow chart. ECG, electrocardiogram.

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The basic ECG measurements were mean heart rate (range) 78.6±13.8 (35-143) bpm; maximum corrected QT segment, 543ms; and maximum PR interval, 294ms. All other measurements are listed in Table 2.

According to the classification used, 1321 (69%) students had normal ECG findings, 554 (29%) had ECG findings suggesting adaptive changes, and only 36 (2%) showed pathologic findings. The ECG findings are listed in Table 3.

This is the first Spanish study to investigate ECG changes in a large sample of the young, healthy population. Two main aspects of the study should be highlighted: the high prevalence of ECG findings (31%), mainly suggesting physiologic adaptation, and the low prevalence of underlying heart disease (0.3%).

Our study identified a higher percentage of ECG findings than earlier series.6,21 These differences may be explained by the criteria used, the study population, and the interpretation and heterogeneity of ECG findings suggesting adaptive changes used in the various series. Cardiovascular screening began in the 2009 to 2010 school year and used the modified ECG criteria described by Corrado et al.,19 which excluded the isolated criterion of left ventricular hypertrophy as a pathologic ECG finding, in an attempt to lower the rate of false positives. Dhutia et al.22 compared various ECG criteria and concluded that later updates improved the effectiveness of cardiovascular screening. In this study, other modifications were made to minimize false-positive results, based on the evidence reported, defining left atrial enlargement and axis deviation as ECG findings suggesting adaptive changes.23 ECG was used for screening based on the meta-analysis results reported by Harmon et al.,24 who compared cardiovascular screening consisting of medical history, physical examination, or ECG, and determined that ECG was the most efficient approach to detecting underlying heart disease. ECG is an inexpensive, noninvasive instrument that is rapid, reproducible, and essential in cardiology. It shows good sensitivity and specificity for detecting SCD-related heart disease, although systematic use in the general population is still controversial.25,26 There is scant evidence of ECG screening in young people, although the consensus is to recommend it for athletes.27

In Japan, systematic screening of a healthy young population showed a prevalence of 0.01% to 0.04% for underlying heart disease among secondary school students28 according to ECG criteria now obsolete. Another Asian study showed a prevalence of 7% pathologic ECGs when using various ECG criteria.6 The most prevalent heart disease detected by ECG screening is Wolff-Parkinson-White syndrome, congenital abnormalities of the coronary arteries, and hypertrophic cardiomyopathy.29 These data agree with our study, which observed 1 case of Wolff-Parkinson-White syndrome, 1 case of coronary abnormality, and 2 cases of left ventricular hypertrophy which did not meet the criteria for hypertrophic cardiomyopathy. There were no cases of arrhythmogenic right ventricular dysplasia or channelopathies.

A low correlation was observed between ECG findings and underlying heart disease. Challoumas et al.30 described a correlation between coronary fistula and T-wave abnormalities on electrocardiography. The case of pre-excitation was confirmed to be Wolff-Parkinson-White syndrome. However, the detection of bicuspid aorta valve and mitral valve prolapse may have been incidental. There were no cases of hypertrophic cardiomyopathy, and only 2 cases were identified of athlete's heart. It is still a challenge to determine whether an ECG finding is pathologic or suggests adaptive changes, and accurate classification has considerable impact on treatment.

SCD has a number of causes, with a low proportion of underlying heart disease, most of them undetectable on ECG. The overdiagnosis of structural heart disease in asymptomatic patients may lead to emotional stress in affected students and excessive costs for the health system due to unnecessary additional tests. The detection of pathologic changes or structural heart disease does not imply that the prognosis can be improved, nor any assurance that the prognosis will not worsen due to poor medical practice. At present, there are reasonable doubts regarding the effectiveness and safety of ECG-based cardiovascular screening.

In an unselected youth population, ECG-based cardiovascular screening identified 31% of ECG changes, most of them suggesting adaptive changes. Underlying heart disease was identified in 1 of every 7 students with pathologic ECG findings, although the overall prevalence of underlying heart disease in the study population was low. In view of the study results, the research team concluded that reasonable doubts remain about the effectiveness and safety of ECG as a large-scale cardiovascular screening instrument in the healthy young population.

The study was partially funded with a research grant from the Ministry of Education, Culture and Sport. None of the article authors have received financial compensation.

None declared.

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