Static and dynamic electrocardiographic patterns preceding torsades de pointes in the acquired and congenital long QT syndrome

The arrhythmogenic mechanisms involved in the triggering of the polymorphic ventricular tachycardia called torsades de pointes (TdPs) remains to be elucidated. In this work, we investigated the static and dynamic profiles of the repolarization interval from the surface electrocardiogram recorded in healthy individuals and in cardiac patients with TdPs. We implemented this analysis just prior to the arrhythmia onset and we computed the delta values based on baseline periods (1 hour prior to event). We measured QT/QTc prolongation, QT variability, ventricular ectopic beats (VPBs) frequency, T-wave amplitude, T-peak to T-end interval, and T-wave complexity. The analysis of these parameters in reference to baseline revealed 1) an increased QTc variability, 2) the presence of VPCs, and 3) the profound changes in T-loop morphology in patients developing TdPs.