Assessment for congenital long QT syndrome.

A 29-year-old male presented for an evaluation of his risk for having congenital long QT syndrome. Despite being asymptomatic and having a normal QTc interval on the resting ECG, a suggestive family history was an indication for a thorough cardiac evaluation. A geneticist reviewed this workup and recommended against genetic testing. While up to 10% of affected carriers of a congenital long QT syndrome gene mutation can be asymptomatic with a normal QTc, consideration of all of the clinical factors allowed for further risk stratification. The evaluation of an ECG for the long QT syndrome includes calculating a corrected QT interval for the heart rate and assessing the T-waves for morphology associated with this syndrome.