Cardiovascular Pre-participation Screening in Children and Adolescents

Background

Sports practice in childhood and adolescence brings physical, psychological and social benefits. However, the cardiovascular demands of exercise may reveal or worsen latent conditions that, if unrecognized, can lead to adverse events, including sudden cardiac death (SCD). Pre-participation evaluation (PPE) is a screening tool designed to detect such conditions and usually includes medical and family history, physical examination and, in some protocols, a resting electrocardiogram (ECG). The ECG increases the sensitivity for arrhythmogenic cardiomyopathies, channelopathies and other electrical abnormalities that may be missed by clinical examination alone. Its routine use in minors remains controversial: European recommendations support routine ECG in young athletes, while North American organizations recommend a selective approach. There is limited evidence on the effectiveness and applicability of these protocols in pediatric populations.

Exercise-induced arrhythmias may not be detected on a resting ECG. A recent clinical consensus statement of the European Association of Preventive Cardiology (EAPC) and the Association for European Paediatric and Congenital Cardiology (AEPC) considers a continuous 3-minute step test with ECG recording during exercise and after abrupt cessation, followed by 3 minutes of post-exercise monitoring, a valid, low-cost and widely available alternative to rule out exercise-induced arrhythmias in pediatric athletes.

Study design and setting

Prospective observational study conducted at the Heart Institute (Instituto do Coração, InCor), Hospital das Clínicas, Faculdade de Medicina da Universidade de São Paulo, Brazil, including children and adolescents enrolled in organized sports in the São Paulo Olympic Program.

Procedures

1. Screening and registration: eligibility check and collection of sociodemographic data (age, sex, self-reported race/skin color), sport, training load (hours per week) and competitive level.
2. Structured medical history: standardized pediatric cardiovascular risk questionnaire applied by trained interviewers, covering symptoms (exertional syncope or near-syncope, exertional chest pain, disproportionate dyspnea, palpitations), personal history (asthma, use of stimulants or supplements, previous moderate or severe coronavirus disease 2019 [COVID-19], hospitalizations), family history (sudden death before 50 years of age, inherited cardiomyopathies, channelopathies, Marfan syndrome, premature coronary artery disease) and sports history (adverse events during training or competition, interruptions due to symptoms).
3. Standardized physical examination: blood pressure (appropriate cuff size, mean of two seated measurements), heart rate, oxygen saturation, weight, height, body mass index (BMI) and optional Tanner pubertal staging; cardiovascular examination including inspection, palpation of the precordium and pulses (including femoral pulses), auscultation in supine and standing positions, Valsalva maneuver when indicated; assessment of Marfan phenotype.
4. Resting 12-lead ECG: calibrated digital equipment (25 mm/s; 10 mm/mV), supine position, after 5 minutes of rest and no caffeine or stimulants in the previous 12 hours. Tracings will be independently analyzed by two cardiologists experienced in sports cardiology, blinded to clinical data. Disagreements will be resolved by consensus or by a third reader. Recorded variables include rhythm, heart rate, electrical axis, PR, QRS and QT intervals, corrected QT interval (QTc), voltages, repolarization, chamber enlargement criteria, pre-excitation, bundle branch and atrioventricular (AV) blocks, T and J waves, and classification as normal athlete-related or potentially pathological according to the study's operational classification.
5. Step test (second-tier evaluation): performed in participants with any of the following: borderline ECG findings (abnormal axis deviation, atrial enlargement, first-degree AV block with PR 200-280 ms, complete right bundle branch block, borderline T-wave inversion in V1-V4 at ages 12-14 years, low QRS voltage, Mobitz type I second-degree AV block); warning symptoms (exertional syncope or near-syncope, palpitations during or after exercise, disproportionate dyspnea, exertional chest pain); abnormal physical examination (heart murmur grade 2/6 or higher, arrhythmia on auscultation, elevated blood pressure or abnormal pressure response); or suggestive history (family history of sudden cardiac death before 50 years of age, previous myocarditis, family history of long or short QT syndrome). Step test protocol: fixed-height step of 45 cm (30 cm for children younger than 12 years). After a supine baseline ECG, the test includes 1 minute of seated rest with continuous 12-lead ECG; 3 minutes of continuous stepping at a standardized cadence with continuous ECG recording; abrupt cessation with the participant seated and continuous 12-lead ECG during the first 3 minutes of recovery; and 3 to 5 additional minutes of monitoring with final clinical examination. Heart rate, rhythm, ST segment, T wave, QTc, symptoms, blood pressure and oxygen saturation will be recorded. The test will not be performed in the presence of fever or acute symptoms in the previous 72 hours, recent confirmed or suspected myocarditis (within 3-6 months), unexplained syncope in the previous week, known severe structural heart disease without cardiologist clearance, resting heart rate above 120 bpm or elevated resting blood pressure, clinical instability or chest pain at rest, known pregnancy, or refusal by the participant or legal guardian. The test will be stopped immediately in case of chest pain, syncope, evident intolerance or significant ECG changes. Results will be classified as normal, borderline or abnormal. The test will be supervised by a physician (cardiologist or trained pediatrician) with an ECG technician, in a clinical setting with basic life support available.
6. Clinical management: participants with potentially pathological findings, abnormal step test results or warning symptoms will be temporarily withdrawn from competitive sports and referred for specialized evaluation (echocardiography, exercise testing, Holter monitoring, cardiac magnetic resonance imaging or genetic testing), with formal communication to legal guardians and to the sports institution. Borderline step test results will be referred for formal exercise testing or echocardiography before sports clearance.

Quality control

Training of the study team, a pilot with 20-30 athletes (including 5-10 step tests), random re-evaluation of 10% of ECGs and clinical forms, and calculation of interobserver agreement (kappa) for ECG categories.

Statistical analysis

Continuous variables will be described as mean and standard deviation or median and interquartile range, and categorical variables as frequencies and percentages. Prevalence will be estimated with 95% confidence intervals (CI). Comparisons will use chi-square or Fisher's exact test for categorical variables and Student's t test or Mann-Whitney test for continuous variables, according to distribution (Shapiro-Wilk test). Multivariable logistic regression will identify factors associated with potentially pathological findings, adjusted for age, sex, sport, training load and pubertal stage when available. Missing data will be addressed by sensitivity analysis, with multiple imputation if more than 5% of key covariates are missing. Significance level: alpha = 0.05 (two-tailed). Additional analyses for the step test include the proportion of indicated versus performed tests, prevalence of abnormal results, agreement between resting ECG and step test findings (kappa), correlation between type of ECG finding and step test result, and cost-effectiveness.

Sample size

Assuming a 95% confidence level, an expected arrhythmia prevalence of 3.6% and an absolute precision of 2 percentage points, the minimum sample size is 334 participants.