Significant QT interval prolongation and long QT in young adult ex-preterm newborns with extremely low birth weight

Abstract

Background. The survival rate for extremely low birth weight (ELBW) infants born preterm is on an increasing upward trend, despite the possibility of neuro-cerebral consequences in later life. To date, scarce information is available on the effect of extreme prematurity on cardiovascular system.

Aim. To verify the presence of standard echocardiographic and ECG alterations in ex-ELBW young healthy adults.

Method. A color Doppler echocardiogram and an ECG were performed on 24 ex-ELBW (4 males and 20 females; mean: 23.2 ± 3.3 years), compared with 24 healthy subjects born at term (C). ECG parameters examined: PR, QT, QT_c, and QT dispersion (QT_d). Gestational age, birth weight, and duration of stay in neonatal intensive care unit were obtained from clinical records.

Results. Transthoracic echocardiography did not reveal differences between ex-ELBW and C, while a significant difference was displayed by ex-ELBW with regard to PR (141.5 ± 13.4 ms vs. 164.2 ± 24.0 ms, p < 0.0003), QT_c (417.0 ± 23.6 ms vs. 369.9 ± 19.5 ms, p = 0.00001), and QT_d (30.4 ± 14.1 ms vs. 24.6 ± 8.2 ms, p < 0.00001). In two patients (8.3%), QT_c exceeded the upper limit of normal range. A statistically significant inverse correlation was observed between QT_c and gestational age (r = −0.67, p < 0.0003).

Conclusions. QT_c and QT_d in ex-ELBW were found to be at the upper limit of normal range and correlated with gestational age and birth weight; in two cases, QT_c exceeded the upper limit. This study, irrespective of the pathophysiological mechanism involved, underlines a potential risk for ex-ELBW of developing ventricular arrhythmias when using drugs capable of prolonging QT interval.

Summary. QT_c and QT_d in young adults previously born preterm with an ELBW (401–1000 g) were generally found to be at the upper limit of normal range and correlated with gestational age and birth weight. This finding underlines a potential risk for ex-ELBW of developing ventricular arrhythmias when using drugs capable of prolonging QT interval.

Keywords:

• Birth size
• gestational age
• long QT

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.