Using published cut-off values overestimated the prevalence of long QT syndrome and different correction formulas did not identify the same outliers. Of the studied formulas, Bazett’s was the most HR-independent and should be preferred in newborns. Several widely used QT heart rate (HR) correction formulas showed considerable over- or undercorrection at the high HRs encountered in newborns. All newborns had a normal echocardiography.ĭuring the first 4 weeks of life, QTcFramingham and QTcHodges showed minor changes, while QTcBazett and QTcFridericia were stable. ≥42 weeks, P = 0.021).ĭescription of the natural history of the QT interval duration during the first 4 weeks of life among 14 164 newborns. Sex and infant size did not affect the QT interval and the gestational age (GA) only showed an effect when comparing the extreme low- vs. Uncorrected QT intervals decreased linearly with increasing heart rate (HR). Applying published QT interval cut-off values resulted in 5–25% of the newborns having QT prolongation. During the 4 weeks, we observed a small decrease of QTcFramingham, and an increase of QTcHodges (both P 0.05). We included 14 164 newborns (52% boys), aged 0–28 days, with normal echocardiograms.
Normal qt interval manual#
Eight-lead electrocardiograms were obtained and analysed with a computerized algorithm with manual validation. The Copenhagen Baby Heart Study is a prospective general population study that offered cardiac evaluation of newborns.
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