Short and long QT syndromes: does QT length really matter?

The short and long QT syndromes are inherited diseases associated with an increased risk for life-threatening arrhythmias. The first case of long QT syndrome (LQTS) was reported more than 150 years ago, and the study of this disease led to crucial advancement of our understanding of channelopathies and associated ventricular arrhythmias. Ten years ago, Gussak et al. reported four cases of idiopathic ventricular fibrillation in individuals from a family with a history of sudden cardiac death exhibited very short QT interval and labeled the disease: short QT syndrome (SQTS). Over this decade, the SQTS was found to be a rare inherited syndrome with the potential to provide novel insights into the main mechanisms of cardiac arrhythmogenicity. In this review, we discuss these mechanisms and provocatively question the role of the QT interval duration as a surrogate marker of increased risk for arrhythmia in both the LQTS and the SQTS.