Long and Short QT syndromes.

The long and short QT syndromes are genetically transmitted arrhythmogenic diseases characterized by an abnormal QTc on the basal ECG and by an increased risk of life-threatening arrhythmias. While in the long QT syndrome well-established diagnostic criteria are available as well as effective treatments, in the short QT syndrome, much less is known in terms of diagnosis, risk stratification and pharmacological treatment. In this chapter we discuss for each syndrome current knowledge on their genetic basis, clinical presentation, diagnosis, risk stratification and therapy. Furthermore, multisystem disorders associated with a prolongation of the QT, such as the Jervell and Lange-Nielsen syndrome, the Timothy syndrome, the ankyrin-B syndrome and the Andersen-Tawil syndrome, are described. Finally, specific subtypes of the long QT syndrome, characterized by high malignancy and frequent failure of available therapies, such as calmodulin-related LQTS and the triadin knockout syndrome, are also reviewed.