QT interval prolongation: preclinical and clinical testing arrhythmogenesis in drugs and regulatory implications.

The assessment about the proarrhythmic risk associated with a particular drug is a major requirement for drugs under development, since many drugs have been withdrawn from market or got under strict pharmacological vigilance because of such a risk. Predicting the development of a life-threatening arrhythmia is a hard task but, in the case of TdP ("Torsades de Pointes"), there are some useful markers. Among them, the prolongation of the QT interval and its heart rate correction (QTc) are the most remarkable.