The site of origin of torsade de pointes

The electrocardiographic (ECG) characteristics and mode of onset of torsade de pointes (TdP) are well described. Less is known about the site of onset of this arrhythmia. This study was conducted to determine if arrhythmias in the long QT syndrome (LQTS) have a predominant site of origin. A retrospective analysis of all episodes of LQTS-related arrhythmias recorded in two university hospitals. Patients with LQTS and no structural heart disease, for whom simultaneous 6-12 leads ECG recording of the onset of TdP was available, were included. None. The site of origin of TDP was defined according to the morphology of the initiating ventricular complex based on validated criteria. Multiple-lead recordings of 1025 LQTS-related arrhythmias, including 151 episodes of TdP and 874 QT-related extrasystoles (impending TdP) were available for 50 patients. The site of origin of TdP was not homogeneously distributed (p