Single-centre retrospective analysis of the best timing for the QTc interval length assessment in neonates.

Objective: To evaluate the best timing for ECG screening in order to diagnose long QT syndrome and lower, at the same time, the false positives. Design: We retrospectively evaluated the corrected QT (QTc) interval in the clinical reports of the ECG screening performed, as per internal protocol. Setting: An outpatient setting in our Unit of Neonatology and Pediatrics, Santa Maria Goretti Hospital in Latina, Italy. Patients: We enrolled 3467 healthy neonates between 14 and 30 days of life. Interventions: The newborns with abnormal QTc interval were invited to subsequent revaluation every 21 days, until normalisation or necessity to refer to a tertiary paediatric cardiology centre. Main outcome measures: Difference in QTc according to patients' characteristics and number of false positives at second ECG evaluation. Results: At first evaluation, 249 (7.2%) newborns had prolonged QTc. We did not find any significant difference in the QTc length according to gestational age (p=0.40) and birth weight (p=0.81). As expected, girls had longer QTc than boys (p=0.01). Only 11 out of 240 (4.6%) and 1 out of 238 infants (0.4%) had persistently prolonged QTc at second and third ECG evaluation, respectively. The QTc decreased significantly at second (p<0.0001) and third evaluation (p=0.0035). Conclusions: In our study, we showed that a single screening performed in healthy infants after 60 days of life could reduce the risk of false positives, with a beneficial impact on public national health system and the chance to start early therapy in case of long QT syndrome.