Abstract 12265: The Impact of Gestational Age on the Neonatal Electrocardiogram

Abstract

Objective: The interpretation of the neonatal electrocardiogram (ECG) is challenging and reflects the underlying developing physiology. The possible effects of gestational age (GA) on the ECG has never been evaluated in a large general population study. We aimed at investigating the effect of GA on neonatal electrocardiographic parameters and create GA-specific reference values. Methods: The Copenhagen Baby Heart Study is a prospective, general population study that offered cardiac evaluation of neonates. ECGs and echocardiograms were obtained and systematically analyzed. GA, weight, height, and other baseline variables were registered. Results: We included 16,462 neonates (52% boys) with normal echocardiograms. Median postnatal age was 11 days (range 0-30 days) and median GA was 281 days (range 238-301 days). Analyzing the ECG parameters as a function of GA we found a significant effect of GA on heart rate (HR), PR-, QRS-, and QT intervals, QRS axis, and maximum amplitudes of R-waves in V1/V6 and maximum S-wave in V6 (all p<0.01). The largest percentual effect of GA was on HR, QRS axis, and R-wave in V1. Boys had longer PR- and QRS intervals and more right-shifted QRS axis within multiple GA-intervals (all p<0.01, Figure: Box plots of ECG parameters subdivided by gestational age intervals and sex ). The effect of GA generally persisted after adjustment for HR, weight, postnatal age, and sex. In addition, when comparing HR, PR interval, QRS axis, QRS duration, uncorrected QT interval, and QTcBazett subdivided into postnatal age intervals, we found a significant effect of gestational age on most ECG parameters within these postnatal age intervals. Conclusion: Gestational age was associated with significant differences in multiple neonatal ECG parameters and the effect generally persisted after multifactorial adjustment. Our results indicate a direct effect of GA on the developing neonatal cardiac conduction system. Use of GA-specific reference values may be useful.