Hereditary arrhythmia corner: learning from challenging patients. Family with suspect LQTS

A brother and sister, presented to our Arrhythmia Clinic for evaluation of possible long QT syndrome (LQTS). They are 18 and 15 years of age, respectively. Their mother has been diagnosed with LQTS and the family history is remarkable for a number of sudden deaths. The electrocardiogram (ECG) of the sister is presented in Figure 1. The siblings had been followed by pediatric cardiology since infancy and now they are referred for further evaluation. They are both asymptomatic and very active teenagers, and are not on any medications. Echocardiograms were normal. Holter monitoring also did not show any rhythm abnormalities in either sibling.The mother had been evaluated as a teenager when she had a presyncopal episode while running track in high school. Her QT interval on one 12-lead tracing showed borderline prolonged QT. She had originally been started on beta-blockers, but she had taken herself off of these over the years. The family history is significant for sudden deaths in several distant relatives. In addition, the mother's aunt had an abnormal ECG in the setting of multiple syncopal episodes. In the interim, she had been treated with beta-blockers.