205 - Incidence of Prolonged QT in infants admitted to NICU

The QT interval (QTi) represents the time on an electrocardiogram (EKG) from depolarization to repolarization and is measured from the QRS complex to the end of the T wave. Neonatal prolonged QT (PQT), with an incidence of 1 in 2000¹, can be acquired or congenital and it is important to recognize because of the risk of serious ventricular tachyarrhythmia, specifically torsades de pointes. This may be fatal if not recognized and treated early. Acquired PQT can be due to electrolyte abnormalities and medications. Congenital long QT syndrome is due to a genetic channelopathy, however, it is unclear how to identify neonates at risk.

QTi likely varies with postmenstrual age (PMA). Screening studies have been done to evaluate QT prolongation. However, variable time points were considered and questions remain. QTi is unaffected by infant sex or size, but premature infants may be more prone to changes². In one study, QT increased in premature infants then decreased whereas it decreased in term infants³. PQT in the first week of life is associated with sudden infant death⁴.

This retrospective and prospective study is being done to compare the incidence of PQT amongst Nursery and NICU patients with serial monitoring and genetic testing in those identified to have persistent PQT or family history.

Objective:

1: Identify incidence of PQT 
2: Determine time course of normalization of QT prolongation
3: Identify prospective risk factors and comorbidities 

Design/Methods:

The study has IRB approval. The retrospective analysis includes EPIC records on 258 infants admitted to the University of Illinois between 2020 and 2022. 4049 infants were admitted, with 1299 NICU admissions.

The prospective pilot study will enroll 175 infants (22 enrolled). Statistical analysis will include logistic regression and ANOVA. 

Results:

Analysis of 60 out of 258 patients that had an EKG during the first month for any indication demonstrates 14 patients with a diagnosis of PQT (QTc > 470). 12 of the 14 were admitted to NICU. PQT was transient and resolved in the majority; however, several had persistence. The prospective analysis aims to identify such patients for genetic testing and monitoring.

Conclusion(s):

PQT has a higher incidence in infants admitted to the NICU. When an EKG is performed in the first month, the chance of finding PQT is high, near 25%. An imbalance in sympathetic tone may predispose to PQT; premature infants are more susceptible. Neonates in the NICU have co-morbidities for PQT. National guidelines are needed to recommend when genetic testing is appropriate and how to monitor patients with documented PQT.