Abstract 18442: ECG Screening of 1-Month-Old Infants May Prevent Out-of-Hospital Cardiac Arrest in Infancy

Background: A national survey of out-of-hospital cardiac arrest (OHCA) of Japan showed that the mean annual incidence of OHCA in infancy ( Methods and Results: Two prospective studies of ECG screening at a 1-month medical check-up were performed to determine the prevalence of infants with LQTS along with questionnaires on OHCA. We included 16 maternity centers in 2011-2012 and 13 centers in 2014-2016 in 8 areas in Japan. A prolonged QT interval was diagnosed when an infant showed a QTc by Bazett’s formula of >460 ms. Infants with a QTc >500 ms were diagnosed with LQTS at high risk for symptoms and medication was started. Genetic testing was performed using the HaloPlex HS custom kit, target regions for 52-54 genes, including causative genes for LQTS and CPVT, and a next generation sequencer. A total of 10,285 infants participated in the study, with 4285 and 6006 infants in the 1st and 2nd studies, respectively. Five infants (2 in the 1st and 3 in the 2nd study) were diagnosed as LQTS at high risk and were treated. No symptoms appeared in these 5 LQTS infants. Genetic testing showed 2 KCNH2 mutations; 3065 delT (L1021fs+34X) and K897T (2690A>C). No mutation was found in the remaining 3 infants. Three infants (1 in the 1st and 2 in the 2nd study) with normal ECGs died unexpectedly during sleeping in the 1st year of life. The prevalence of LQTS at high risk and sudden unexpected death was 49 and 29 per 100,000 live births, respectively, indicating a combined prevalence of 78/100,000. Discussion and Conclusions: Previous studies have shown that approximately 10% of victims of sudden infant death syndrome have causative genes of LQTS. The combined prevalence of LQTS at high risk and sudden unexpected death in the present study (78/100,000) was similar to the annual occurrence of OHCD in infancy in Japan (55-83/100,000). This finding suggests that ECG screening may prevent unexpected sudden death more than expected.