Extrasystoles or short bradycardias of the newborn seldom require subsequent 24‐hour electrocardiographic monitoring

Abstract

Aim To retrospectively assess the indications for and findings on 24‐hour electrocardiographic (Holter) monitoring in newborns, focussing on bradycardias and extrasystoles. Methods Data included 337 term‐born infants. Holter indications were categorised into bradycardias below 80 beats per minute, extrasystoles, any tachycardia and other. Heart rate below 60 beats per minute, pathological atrioventricular conduction, supraventricular or ventricular tachycardia, or either atrial premature contractions over 10% or ventricular premature contractions over 5% of total beats were defined as significant arrhythmia on Holter. Results The median age was 6 days (range: 2–62 days). Bradycardia (42%) or extrasystoles (32%) were the most common Holter indications. Fifty‐three infants (16%) had significant arrhythmia on Holter. Heart disease or 12‐lead electrocardiogram expressing extrasystoles or conduction abnormalities were associated with significant arrhythmias (p = 0.046 and p < 0.001, respectively). Twenty‐seven of 109 infants (25%) with extrasystoles as a Holter indication had abnormal Holter results, but only seven (6.4%) had significant arrhythmia on Holter if the 12‐lead electrocardiogram was normal. No pathology was found behind bradycardias below 80 beats per minute in the absence of heart disease. Conclusion Among term newborns with extrasystoles or bradycardias, Holter monitoring could be targeted to infants with heart disease or abnormal electrocardiograms.

Heart rate in newborns is associated with age, sex and maternal levothyroxine therapy

“…In this study population of newborns, where the majority were boys, males exhibited lower HRs compared to females. The observed association between HR and sex in neonates is supported by some previous studies, 4,8–10 whereas other studies observed sex differences in HR among older children but not in newborns 11,12 . It is plausible that the sex difference in HR is inherently present from birth but becomes more pronounced with age.…”

“…The association between advancing age and HR was linear -as we have previously demonstrated in healthy newborns. 4 While previous studies have reported an increase in the mean or median HR from birth to approximately 1 month of age, 5,6 our findings suggest that the impact of chronological age is evident in all aspects of HR, including the minimum, mean, and maximum HR. According to HR variability studies, the increase in HR during neonatal period is explained by postnatal autonomic nervous system maturation.…”

“…In our previous study, the association between HR and GA was statistically significant. 4 None of the newborns received HR-lowering medication. Maternal sedative and antiarrhythmic medications can cross the placenta and reduce foetal HR.…”

“…Using a HR threshold below 80 bpm, nearly 80% of newborns in the study exhibited bradycardia on Holter monitoring, while applying our new age‐specific reference values 4 reduced the prevalence to 15%. In a previous study, bradycardias were reduced from 30% to 7% when the definition of bradycardia was based on the baseline HR during the monitoring instead of a HR below 80 bpm 2 .…”

“…Our recently published age‐specific reference values for HR in newborns were used 4 . The definition for bradycardia was either a HR <80 bpm or a minimum HR < −2 standard deviations (SDs) of age‐specific reference data.…”