The dark side of the QT interval. The Short QT Syndrome: pathophysiology, clinical presentation and management.

A large number of studies has been carried out to investigate the pathophysiology and the clinical implications of QT interval prolongation in the ECG over recent years. It was only in the last decade, however, that the scientists have focused on the specular aspects of the long QT syndrome (LQTS), and it is now well established that the abnormal shortening of the QT interval is associated with meaningful clinical consequences and adverse outcomes. The aim of the present article is to summarize knowledge and existing evidence about the Short QT Syndrome (SQTS). SQTS is a rare, albeit largely underdiagnosed, genetically determined disease, which is characterized by a high tendency to develop life-threatening arrhythmias. The two clinical landmarks of SQTS are the presence of a short QT interval (i.e., less than 320 ms) in a structurally normal heart. The disease is now classified as a “channellopathy”, and is principally caused by a defective functioning of both potassium and calcium ion channels. The underlying genetic anomalies cause an abnormal ripolarization and a reduced refractoriness of myocardiocites. Pharmacologic treatments are mainly tailored to slow the conduction and to prolong the refractory period of myocardiocites. The implantable cardioverter and defibrillator (ICD) is currently considered the therapeutic gold standard.