BACKGROUND: An ongoing discussion has been the effectiveness of neonatal electrocardiography (ECG) screening for long QT syndrome (LQTS). OBJECTIVE: The aim of this systematic review was to assess the consequences of ECG screening for prolonged corrected QT (QTc) interval in infants younger than 1 month. METHODS: We searched the PubMed, Scopus, and Web of Science databases in June 2024. The incidence rates of prolonged QTc, defined as >
450 ms, were calculated per 1000 neonates. Prolonged QTc cases, including normalization during follow-up, LQTS diagnosis, and sudden infant death syndrome (SIDS), were analyzed. RESULTS: Eight studies were included. Five studies using a cutoff QTc >
450 ms reported incidences ranging from 5 (95% confidence interval [CI], 5-6) to 79 (CI, 60-102) per 1000 neonates. Six studies with a cutoff of >
460 ms reported incidences ranging from 1 (CI, 1-2) to 53 (CI, 50-57). Five studies (cutoff QTc >
470 ms) had incidences varying from 1 (CI, 0-1) to 28 (CI, 21-35). In 6 studies, QTc normalization during follow-up occurred in 57.1% to 95.2% of neonates with prolonged QTc. The diagnosis of LQTS was reported in 4 studies, with 21 of 51,817 (0.04%) neonates later diagnosed with LQTS. Two studies reported SIDS outcomes, finding prolonged QTc in 8 of 24 and 3 of 3 SIDS cases. CONCLUSION: The incidence of prolonged QTc varied widely across studies. Only a small proportion of neonates with prolonged QTc were diagnosed with LQTS during follow-up. Further research with standardized study factors and comprehensive genetic analysis is needed to determine the utility of and indications for neonatal ECG screening.