Influences of Age, Sex, and Heart Rate on Corrected QT Interval Values Calculated by Using Bazett and Fridericia Formulas in Children and Young Adolescent Athletes

OBJECTIVE: To analyze QT characteristics in children and adolescent athletes (11-16 years) using the Bazett and Fridericia formulas and compare the results by age, sex, and heart rate (HR). DESIGN: Cross-sectional study. SETTING: Sports federations in the Spanish autonomous community of La Rioja. PARTICIPANTS: 3672 federated athletes aged 11 to 16 years. INTERVENTIONS: None. MAIN OUTCOME MEASURES: We analyzed the 12-lead resting ECGs performed as part of the baseline screening program of sports federations. Mean corrected QT (QTc) values and percentiles were calculated using the Bazett (QTcB = QT/RR1/2) and Fridericia formulas (QTcF = QT/RR1/3). These values were compared according to age, sex, and HR. RESULTS: Most athletes (99%) showed a normal QTc. Only four adolescent boys had values above 460 ms (with Bazett >455 ms) using the Fridericia formula. One athlete had a significantly prolonged QTc with both formulas. Using the Bazett formula, significant differences in QTc were observed by sex (longer in adolescent girls), age (longer in 11-12 year olds), and HR (increases with higher HR). Still, with the Fridericia formula, no significant differences were observed in this age group, but differences were observed by sex. For HR, substantial differences were observed when comparing the 60 to 90 bpm range with the low and high intervals, with no differences found between bradycardia and tachycardia subgroups. CONCLUSIONS: Our study shows that using the Bazett and Fridericia formula to measure QTc is recommended for cardiovascular screening in young athletic populations. The values obtained can serve as a reference for the early detection of long QT syndrome in ECGs performed in this population.