Sexual maturity rating: a marker for effects of pubertal maturation on the adolescent electrocardiogram

The heart is known to participate in the adolescent growth spurt. A peak increase in transverse diameter coincides with peak height velocity during pubertal maturation. The effects of maturation on the adolescent ECG were explored using sexual maturity rating (SMR) as a marker. ECGs were obtained from 751 patients 8 to 20 years of age seen for routine physical examinations. A total of 33 standard ECG measures were analyzed, with subjects separated by sex and SMR. Different trends were seen in boys and girls during the course of maturation for the majority of R and S wave amplitude measurements. Lower mean amplitudes were seen consistently in more mature (SMR 4 and 5) girls than less mature girls and all boys. The clinical implication of these findings is illustrated by analysis of the sum of RV5 and SV2, one of the criteria for left ventricular hypertrophy, by sex and SMR. No significant difference in the sum is noted for boys across five SMR groups. Girls, in contrast, show a steady decrease in the sum with advancing maturation. These trends are not as clearly shown when subjects are grouped by broad chronologic age ranges, as had been the practice in developing current adolescent ECG tables. These findings suggest that development of standard ECG tables in which SMR and sex have been taken into account might enhance interpretation during adolescence.