Repolarization abnormalities in the newborn.

The recognition of ventricular repolarization abnormalities
in the newborn carries several and significant implications, because it
calls attention to the possibility of dealing with an infant affected by the
long QT syndrome (LQTS). This article provides key elements for the
correct measurement of the QT interval in newborns and succinctly
reviews some aspects of the disease. It gives normative values on theQT
interval distribution in the firstmonth of life based on a prospective study
in more than 44,000 infants. It shows the probability, based on the QTc
observed in two recordings, to find disease-causing mutations. The data
indicate clearly that widespread electrocardiographic screening in the
newborn allowsearly identification ofmost, ifnot all, the infants affected
by LQTS with marked QT prolongation and thus of those at higher risk
for life-threatening arrhythmias and sudden death. Through the affected
infants, it becomes possible to identify the family members affected by
LQTS, including the ‘‘silent mutation carriers’’; our study shows that
disease-causing mutations are found in 51% of the family members.
Because early recognition leads to the implementation of effective
preventive strategies, it follows that electrocardiographic screening will
avoid preventable deaths either in the first year of life when they are
usually labeled as ‘‘sudden infant death syndrome’’ or later in life. The
case is made for medicolegal implicationswhenever neonatologists and
pediatricians fail to inform the parents of a newborn child of the prevalence
of LQTS (one in 2000), of the effectiveness of existing therapies,
and of the diagnosis with a simple electrocardiogram.