Electrocardiographic characteristics, anthropometric features, and cardiovascular risk factors in a large cohort of adolescents

Abstract

Aims: The characteristics of electrocardiographic (ECG) patterns in the general population of adolescents are insufficiently defined. The purpose of this study is to report ECG patterns and their association with anthropometric characteristics.

Methods and results: Twenty-four thousand and sixty-two students of Roman schools, aged 12-19, were screened with ECG and physical examinations. Electrocardiographic abnormalities were classified as either minor/non-clinically relevant or major, and anthropometric measures were evaluated per age class. Obesity prevalence was 20.9%, with a higher rate in younger students (P < 0.008 for all comparisons, except for the pair 16-17 vs. 18-19 years). Stage 1 hypertension was found in 3.14% of adolescents, Stage 2 hypertension in 0.45% of adolescents, and isolated systolic hypertension in 11.7% of adolescents. Heart rate and QT interval corrected for heart rate (QTc) decreased with increasing age. The QTc was longer in females than in males over 14 years. A higher rate of incomplete right bundle branch block (RBBB) was observed in underweight students (21.58% vs. 15.10% in non-underweight students, P < 0.0001). Complete RBBB was the most common major ECG abnormality (1.6%). It was associated with height irrespective of age, sex, and body mass index (odds ratio 17.9; 95% confidence interval 5.0-64.6) and more frequent in students regularly practicing physical activity (1.80% vs. 1.02%, P = 0.0009).

Conclusion: Heart rate and QTc decreased with increasing age. The QTc was longer in females than in males over 14 years. RBBB was the most common major abnormality and was associated with higher stature. The prevalence of some cardiovascular risk factors in adolescents is provided.

Figure 1

Arterial blood pressure value distribution in the different age classes. Prevalence of low blood pressure values (SBP < 100 mmHg, DBP < 60 mmHg, or both), normal blood pressure (<90th, in students 12–15 years old; <130/85, in students 16 years and older), high normal (>90th to <95th percentile, in students 12–15 years old; 130–139/85–89 mmHg, in students 16 years and older), Stage 1 hypertension (95th–99th percentile and 5 mmHg, in students 12–15 years old; 140–159/90–99 mmHg, in students 16 years and older), Stage 2 hypertension (>99th percentile plus 5mmHg, in students 12–15 years old; 160–179/100–109 mmHg, in students 16 years and older), and isolated systolic hypertension (SBP >95th percentile and DBP <90th percentile, in students 12–15 years old; >140/<90 mmHg in students 16 years and older) observed in the different age classes. Blood pressure values have been adjusted for age, sex, and height. Blood pressure cut-off values of the different categories have been defined in accordance with the classification reported in 2016 guidelines of the European Society of Hypertension. DBP, diastolic blood pressure; ISH, isolated systolic hypertension; SBP, systolic blood pressure.

Figure 2

Heart rate, PR, QRS, and QTc interval in males and females in the different age classes. F, females; M, males; QTc, QT interval corrected for heart rate.

Figure 3

Prevalence of major ECG abnormalities and complete RBBB by age class and of complete RBBB by stature subgroup. Left panel: prevalence of major ECG anomalies and complete RBBB in each age class. Right panel: prevalence of complete RBBB in subgroups of height < and >90th centile. ECG, electrocardiographic; RBBB, right bundle branch block.