Probability of diagnosing long QT syndrome in children and adolescents according to the criteria of the HRS/EHRA/APHRS expert consensus statement.

Aims  The present study aimed to determine the probability of diagnosing long QT syndrome (LQTS) in children and adolescents based on the HRS/EHRA/APHRS criteria for LQTS. We used data of a school-based electrocardiographic screening programme in Japan. Methods and results  The total numbers of subjects who participated in the screening programme between 2008 and 2013 in Kagoshima, Japan, were 33 051 first- and 34 751 seventh-grade students, aged 6 and 12 years, respectively. The screening process consisted of three steps of examination: the first screening, and the second and third examinations. Among the total subjects, 32 982 first graders (99.8% of the total) and 34 572 seventh graders (99.5% of the total) participated in the first screening. After the first, second, and third screening or examinations, the programme determined 10 first and 32 seventh graders as having a high probability of LQTS according to the HRS/EHRA/APHRS criteria for LQTS. The probability of diagnosing LQTS by the screening programme was 1:3298 (0.30/1000) and 1:1080 (0.93/1000) in first and seventh graders, respectively. During the study periods, three subjects of 7th graders were already diagnosed as having LQTS at the first grade. Therefore, the overall probability of diagnosing LQTS was 1:3298 (95% confidence interval, 1:2036 to 1:8673) and 1:988 (95% confidence interval, 1:742 to 1:1477) in first and seventh graders, respectively. Conclusion  This study shows important data on the probability of diagnosing LQTS as ∼1:3300 in subjects aged 6 years and 1:1000 in those aged 12 years based on the HRS/EHRA/APHRS criteria.