Abstract 18342: Electrocardiographic Screening of One-month-old Infants with High Risk for Sudden Infant Death in Japan

Abstract

Backgrond: Sudden infant death syndrome (SIDS) is one of the major causes of death in infancy with the highest prevalence at about 2 months of age. Genetic studies have shown that about 10% of cases diagnosed as SIDS carry functionally significant mutations in long QT syndrome (LQTS) genes. In Japan, medical examinations at one month of age are performed for all infants currently. Aim: We assessed the hypothesis that electrocardiographic screening of one-month-old infants is able to screen infants with LQTS and those with risk of sudden death other than LQTS. Methods: The study was conducted in eight areas in Japan. Twelve-lead electrocardiograms were recorded and the QT/RR intervals of three consecutive beats were measured. Our prospective study showed that a formula to minimize the effect of heart rate for infants was QTc=QT/RR 0.43 and a provisional criterion of a QTc≥0.44 was appropriate. To assess the validity of the criterion, all infants with a QTc ≥0.43 were followed. Results: Of 4,319 infants who participated, 6 infants had a QTc value of ≥0.44 at one-month-old. From the follow-up ECGs, four infants were diagnosed as LQTS clinically. Two infants showed progress prolongation of the QTc intervals; propranolol and mexiletine were administered when their QTc values exceeded ≥0.50 0.43 . Genetic testing revealed a KCNH2 mutation (3065 delT, L1021fs+34X) in one of these two infants. Remaining two infants with a QTc ≥0.44 had been following without medication. All 10 infants with the QTc values between 0.43 and 0.44 showed decline in their QTc values during follow-up. The study also screened infants with WPW syndrome in 3, VPC in 9, CRBBB in 5, and situs inversus totalis in 1. Among 3 infants with WPW syndrome, 1 infant was diagnosed as noncompaction with heart failure (ejection fraction of 50% at the 1 st visit). A sharp drop of the ejection fraction to 28% emerged a few weeks later and medication was started. Conclusions: Electrocardiographic screening of one-month-old infants is successful in preventing deterioration of infants with risk and may prevent sudden infant death.