Short QT syndrome in a boy diagnosed on screening for heart disease

We report on an asymptomatic 10-year-old boy who had a short QT interval (corrected QT interval, 260 ms). Short QT syndrome (SQTS) was detected in a school screening program for heart disease and the patient was subsequently diagnosed as having N588K mutation in the KCNH2 gene. Quinidine prolonged the QT interval, but not the QU interval. During treadmill exercise stress test, QT and QU intervals responded differently to heart rate changes, suggesting a mechanoelectrical hypothesis for the origin of the U wave. Although rare, attention should be paid to SQTS, which is associated with potential fatal arrhythmias.