24-hour Holter findings in infants with in-utero exposure to the Zika virus: a series of cases

Severe neurological problems and other special manifestations such as high prevalence of structural cardiac changes has been described in infants vertically exposed to the Zika virus (ZIKV) and has been called congenital Zika virus syndrome (CZS). Previous studies have shown that the 24-hour Holter heart rate variability (HRV) analysis allows the prediction of worse outcomes in infants with neurological impairment and higher risk of sudden infant death syndrome (SIDS), hypertension, diabetes mellitus and other cardiovascular diseases. This study describes the 24-hour Holter findings of infants with confirmed vertical exposure to the ZIKV by positive polymerase chain reaction (PCR) assays in the mother's blood during pregnancy and/or in the urine or cerebrospinal fluid of the newborn. Data analysis was descriptive and included two subgroups according to the presence of fetal distress, positive PCR to ZIKV in the newborn, CZS and severe microcephaly. Heart rate, pauses, arrhythmias, ST segment and QT interval analyses and HRV evaluation through R-R, SDNN, pNN50 and rMMSD were described. The Mann-Whitney test was performed to assess differences between the two subgroups. The sample consisted of 15 infants with a mean age of 16 months, nine of whom were male. No arrhythmias or QT interval changes were observed. The comparison of HRV through the Mann-Whitney test showed a significant difference between patients with and without CZS, with and without severe microcephaly, with lower HRV in the groups with severe microcephaly and CZS. The study suggests that there is an increased risk of SIDS and cardiovascular diseases in this group of patients.