Abstract 15531: Limited Relationship Between Echocardiographic Measures and Electrocardiographic Markers of Left Ventricular Dimensions in Healthy Children

Abstract

Background: Prior ECG standards in children have largely been defined without echo confirmation of normal anatomy. The Pediatric Heart Network Normal Echocardiogram Z-score Project provides a racially diverse age/sex classified group of healthy children with normal echos that included 2170 matched contemporaneous digitally acquired ECGs. We hypothesized that ECG measures and z-scores of left ventricular (LV) dimensions are correlated in healthy children. Methods: This was a secondary analysis of the previously described cohort. Six ECG measures historically associated with LV size (R V5, R V6, S V1, Q III, axis, R V6+S V1), and 13 paired echo measures were identified a-priori with LV Mass (LVMass-z) and left ventricular end diastolic volume (LVEDV-z) z-scores serving as primary echo measurement predictors. Pearson or Spearman correlations were calculated for each of the 78 ECG- echo pairs. Regression analyses were performed to assess how much variance in ECG measures was explained by variation in LV dimensions and by demographic variables (age, sex, race). Results: ECG and echo measurement correlations were significant and concordant in 41/78 (53%), though many were significant and discordant in 13, (17%) or not correlated in 24 (31%). Of the 6 ECG measures of LV size, 5 correlated in the clinically predicted direction for LV Mass-z and LVEDV-z. While many of the correlations were statistically significant, the correlations were weak (0.05-0.25). R 2 was higher for demographic variables than for echo measures in all pairs, but even with demographic variables included, the overall R 2 was < 0.17. Conclusions: In a large, diverse cohort of healthy children, there was a positive association between echo measures of LV dimension and mass and the most commonly used ECG measures of LVH. However, these correlations were weak and most of the variability in ECG measures was explained by factors other than echo derived mass or volume or measured patient demographic variables. These data question the utility of traditional ECG measurements of LV size as standalone indications for further cardiac evaluation in healthy children.